00:00
Welcome to the Automotive Diagnostic Podcast.
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We're going to explore ways to sharpen our diagnostic skills, find learning resources, and hear from
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I highly recommend it.
01:25
Hey, what's going on, Automotive World?
01:30
Welcome to another episode of the Automotive Diagnostic Podcast.
01:33
My name is Sean Tipping and I'll be your host once again for this week's episode.
01:37
Thank you so much for joining me.
01:39
Just me on the show this week and I am going to be talking about mice this week
01:47
Rodents, it's usually mice.
01:50
You see this a lot on vehicles where there is rodent damage to the electrical system.
01:56
It's usually wiring.
01:57
I'm sure everyone out there, if you've been in this industry for any period of time,
02:02
you've seen the same thing.
02:03
But I had a really interesting one this week.
02:08
Because of the damage that was done, how it was done, it created a very interesting
02:13
problem and it got me thinking about some of the other rodent damage vehicles
02:18
that I've seen over the years where, I mean, number one, it's usually an open circuit,
02:24
but sometimes can be a shorted circuit or in the case of the one I dealt with this week,
02:29
it was open and shorted, right?
02:32
So you didn't have power where you expected to have power and you did have power and
02:36
another wire you didn't expect to have power on.
02:39
So obviously those can happen and it's, you know, not a huge mystery once you
02:44
find where the damage is, you can see it pretty plainly.
02:48
The thing about rodent damage to wiring is that for the most part, it is going to be a
02:54
unique one-off scenario that you may never see that exact fault on that type of vehicle ever again.
03:04
Now, that's not 100% true.
03:06
And I'll give you an example because, of course, there are specific areas in the vehicle
03:12
within components that might attract a rodent, right?
03:16
They are going to go for the small spaces that are maybe contained, a place where that they feel
03:23
that they could build a nest, right?
03:25
And they do they bring in stuff and you can see the like padding from or insulation or
03:31
nuts and seeds and, you know, things like that, you'll see little nests.
03:36
But then wherever they pick to make their home, they end up chewing on wiring and somehow
03:44
or another, it always ends up being the can wires, it seems, that they go for.
03:49
There was an issue with, I think it was either Toyota or Ford where they had like a
03:54
soy based insulation on their wiring and it was almost like attractive to rodents and so
04:00
they were chewing up the insulation like crazy on these.
04:03
But I mean, again, we've been seeing this for years.
04:05
This is nothing new.
04:06
Of course, up here in Minnesota, it seems to happen in the winter time even more
04:11
so because of course, they're looking for a nice warm place to spend the winter and
04:15
hey, under the hood or in the cab of the vehicle is a great place to make a little mouse home.
04:22
So of course, chewing wiring, we're going to have issues and that's what I'm going to be
04:26
talking about today.
04:27
But also just kind of the uniqueness.
04:29
Now, let me start off actually with one that I thought this was pretty crazy that
04:36
the mouse ended up chewing the same wire on a similar truck years apart.
04:41
So I'll give you the scenario and actually I don't even have the exact year.
04:45
I think it was around a 2010 ish Ford F-150 and it wouldn't start and you couldn't
04:51
communicate with a number of control modules.
04:54
It was the ABS, the PCM and I think the airbag control module, maybe one other one.
05:01
So there was four or five different modules you couldn't communicate with.
05:06
And you know, you could look at the live network thing and OK, all these modules are
05:10
offline and I ended up finding, OK, what do they share?
05:14
They all share a power feed from a run start relay that's in the fuse box under
05:20
the hood. And this is the old style where that fuse box is like right front
05:24
and center under the hood when you open it up kind of over the top of the fan
05:29
shroud. So relay in there, body control module operates, it turns it on, it sends
05:34
power to these other modules. And interestingly enough, this is hindsight.
05:39
I was actually putting this together for a network class that I presented.
05:44
But you could actually see on the CAN bus networks that these modules lived on
05:50
where, you know, they should be communicating, but they're not.
05:53
You could actually see the bias voltage of the network be lower than where
05:57
you expected. Now, this is kind of a networking thing, but I just thought I
06:03
pointed out because you can see it plain as day when these modules are not
06:08
receiving the power feed that they need, but they're still on the bus like
06:12
physically connected. They'll actually drag that bias voltage down below
06:16
two and a half. It's just something to pay attention to, right?
06:20
If you see your bias voltage on your CAN bus network is not at two and a
06:23
half, you know, it's significantly elevated or it's below, you can say,
06:30
hey, I might have a power feed issue to a module or modules in this case.
06:35
And then the opposite, if it's higher than expected, I might have a ground
06:38
issue to a module or modules. And it's not going to solve the problem
06:42
for you just by observing that. And I'm sure there's circumstances where
06:46
maybe it doesn't necessarily apply to the fix, but a lot of the times it
06:51
can at least get you thinking like, oh, okay, I see a bunch of modules I
06:56
can't talk to my bias voltage is lower than I'd expect. Do they share a power
07:01
feed? That would be the next thing is not like to make that like
07:04
determination right on the spot. I definitely have this, but let me
07:07
take stock of these modules and see, do they share a power feed? And
07:11
then maybe I'll go after that. Now, full transparency. This was back
07:15
in like, I think 2019 that I diagnosed this vehicle. So it was
07:21
a long time ago, but I had some screenshots of it and stuff. I
07:24
wasn't aware of looking at bias voltage. I did not make that that
07:28
clarification at that point. I went through the hard way and then I
07:33
just ended up checking like, hey, I have all these modules. The
07:37
CAN bus pattern actually looked halfway decent. Again, paying
07:41
specific attention, you could see the bias is a little low, but
07:44
the traffic was still there. I could still communicate with
07:46
other things. I didn't seem like I had an open, I think, you
07:49
know, 60 ohms on the on the bus that they were on. And I
07:54
eventually got to the point that, okay, all these modules share a
07:56
power feed found that it was that run start relay, which is
08:01
controlled by the BCM. It was not being controlled by the BCM.
08:05
There's a single wire the BCM uses to control that relay in
08:08
that under hood fuse box, you know, wasn't getting the
08:11
signal and found that there was a wire underneath that fuse
08:17
box that was chewed through by a mouse. Okay, easy enough to
08:21
fix, right? Just patch up the wire and you're good to go. And
08:24
it makes sense that the mouse wanted to get into this little
08:27
contained space underneath the this fuse box because it's
08:30
housed by like a plastic shell. And of course, you got all the
08:34
wires underneath the fuse box to all the fuses and all the
08:37
relays. And the mouse just decided to chew that one, I
08:41
think it was a purple wire. And that was the only one it
08:43
chewed, right? And why who knows? That's the one it picked,
08:46
though. Now, fast forward about four years. This was 2023. 20.
08:55
Yeah, I think it was I think it was 23 that I looked at another
08:59
Ford F 150. And the funny thing was this was about a mile from
09:04
the first shop that I made that diagnosis on. It was in the
09:08
same town, different shop, different truck, but very
09:11
similar, like the same setup. And it had the exact same modules
09:15
that were offline. And I remember, like looking at it, because I
09:19
had made a case study out of the first one. And I remember
09:21
looking at I'm like, Oh, hey, I remember all these modules.
09:24
And this time around, I had been through some classes, got
09:28
some information. And I did notice that can bus voltage was
09:32
like, Oh, it is a little low. And the last time I had this,
09:35
it was, you know, that run start really not providing
09:38
power to the modules in question. So I go and I find and, okay,
09:41
I'm not getting a signal to that relay. And I pull up the bottom
09:45
of the fuse box, and a mouse had gotten into the bottom of
09:48
fuse box and chewed up that one single purple wire again. Now,
09:53
again, different truck, I'm assuming different mouse, different
09:56
shop, but exact same wire chewed underneath that fuse box.
10:00
So I guess I'm putting this out there to say, my my
10:04
episode idea was wrong. Sometimes they do pick the same
10:09
spot. How often that's going to happen. I don't know. But I
10:12
thought it was pretty funny that the exact same problem
10:15
happened to the it wasn't a host of wires. It was just one
10:18
wire that the mouse decided to choose. Does it have something
10:23
to do with the color? I have no idea. Anyways, that was
10:26
interesting. But obviously, we've seen mice get into, you
10:30
know, things like underneath fuse boxes and stuff and chew
10:33
up wires. Now, that's just an open circuit, right? And there's
10:36
nothing really that special about finding an open circuit,
10:39
right? It's identifying the circuit that you have a problem
10:41
with, identifying that, hey, it's open, and then it's
10:44
finding the open that, you know, generally makes for a
10:48
fairly boring podcast to just tell you about finding open
10:50
wires. Okay. But sometimes you can have other things
10:55
happen as they chew through multiple wires, you can have
10:58
a short between two wires, right? And like I mentioned,
11:01
they seem to pick the can bus wires for whatever reason. Maybe
11:06
it's that mice chew other wires, and they're less critical
11:09
circuits, and customers don't bring their vehicles in if
11:12
some minor thing like a, you know, a switch for a dome light
11:17
doesn't work or something like that. They're just like
11:19
whatever, but a can bus line that's chewed is going to
11:21
disable the vehicle. So we see those more that might be why
11:25
that seems to be the case more often, but somehow or
11:28
another, they always seem to find those can bus wires.
11:31
Maybe it's a twisted pair. I don't know. Anyways, I had a
11:35
Ford Escape recently, where that was the case. Not only did
11:39
they chew through the can lines, but they shorted them
11:42
together, right, because they're pulling those little
11:44
copper strands apart. And then they kind of just leave
11:48
it in a mess. And then those wires are touching
11:50
together. And when you have a shorted can bus,
11:53
obviously, if you own check between the high and the
11:56
low side, you're gonna get zero ohms, not OL, not
12:00
120, not 60. You have zero. It beeps if you have it on
12:03
the continuity setting. And that is a short together.
12:07
If you scope a shorted can bus, and many of you have
12:10
seen this, it's pretty much going to be a flat line.
12:13
Now, not perfectly. You'll if you look closely at the
12:17
line on your scope, you'll see just a little bit of
12:21
movement off of that bias voltage, right, you're
12:24
going to have two and a half. And if you zoom in on
12:27
it, you're like, Oh, that actually looks like what
12:29
could be a can packet. Now, it definitely doesn't
12:32
look right. There's not much movement off of that
12:35
bias, but you'll actually see a little bit of something
12:37
even they're shorted together because the modules
12:40
are still trying to communicate. But with the
12:43
high and the low shorted together, they cancel
12:45
each other out. So it's not usable. You can't
12:48
talk to anything. That was the case on this
12:49
escape. And, you know, nothing real special
12:52
about this. I just basically broke the network
12:55
down into sections and followed where that short
12:58
was it ended up being underneath the battery
13:01
tray. There's a harness that runs near the ABS
13:05
module and the can lines are right on the top of
13:08
that harness kind of exposed actually. And of
13:11
course, the mouse does a great spot for the
13:13
little mouse underneath the battery tray on this
13:16
harness got hungry chew the wires. That sort
13:18
of stuff happens as well. So that went now
13:21
I'm going to get to the interesting car
13:23
here. And again, you know, spoiler, it's
13:25
thrown damage. But I thought the way that the
13:29
symptoms presented themselves were pretty
13:31
interesting on this one, you know, learned a
13:33
little bit about the car. Will I ever see this
13:36
exact same problem on this car? Again,
13:40
probably not. Because it was a real specific
13:43
way that the mouse chewed through the wires
13:46
that allowed this to happen. So this was a
13:49
2019 Toyota Corolla. And the issue that
13:53
they were having was once you start up this
13:57
vehicle, and sometimes you had to drive it, but
13:59
it would happen pretty frequently, you'd shut
14:01
off the vehicle and the HVAC controls in the
14:06
center of the dash would stay on and you can
14:08
control the HVAC system indefinitely or until
14:11
the battery died. And you could take the key
14:14
out of the ignition. This was a blade style
14:16
key on this one. And obviously the car
14:19
shuts off, but that HVAC system keeps
14:21
running, drains the battery, but you could
14:23
operate it like the key was still on. And the
14:25
shop had been through this and they replaced a
14:27
few things, trying to get this resolved. But
14:31
they're really busy and they just didn't have
14:33
the time to, you know, dig into this fully. So
14:37
we take a look at it. And at first it wasn't
14:39
acting up. But they said, Well, sometimes
14:42
when you drive it, it happens and it's pretty
14:44
consistent. And they actually just hopped in
14:47
it, took it around the parking lot, and then
14:49
shut it off. And then it was acting up. So it
14:51
didn't take much to get this to happen. And so
14:53
then it's in the bay, key is off and verify
14:56
HVAC controls are on the little screen. It's
14:59
an automatic system. And there's just, you
15:02
know, a few things on the screen. You can
15:03
control everything. You can run the fan.
15:06
Actually, he had the fan unplugged so that
15:08
it wouldn't completely drain the battery.
15:11
Hey, have you ever been faced with the
15:12
challenge of sourcing, installing and
15:16
programming a used control module in a
15:18
vehicle? I know a lot of us have. It seems
15:21
to be happening more and more often today
15:24
with the volume of control modules on
15:26
vehicles, the cost of some new ones, or
15:28
even the availability of new control modules
15:31
in some cases used may be the only option.
15:35
So what do you do here? I strongly
15:37
recommend checking out SJ auto solutions
15:40
and Tommy Oliva. Tommy offers a cloning
15:43
service for use control modules to make
15:46
these things plug and play for the
15:49
vehicle that you're working on. In a lot
15:51
of cases, he is also able to source the
15:53
control modules if you're unable to
15:56
locate one for the vehicle that you're
15:58
working on. But once you get connected
16:00
with Tommy, he's going to offer fantastic
16:03
support from start to finish to make
16:05
sure that that control module is going
16:07
to work in your application. He's also
16:10
got tech support that he offers through
16:12
his website, along with some free
16:15
resources there as well on
16:17
information about used control module
16:20
programming. So make sure to check out
16:22
SJ auto solutions. I can't recommend that
16:25
enough. But anyways, we get into it
16:29
and they had already replaced the AC
16:32
amplifier because he did note that
16:35
when the AC amplifier, which is the
16:38
control module that's really in charge
16:40
of the HVAC system, you have the
16:42
display screen, but that is just for
16:44
controls. And it links on a Lin bus to
16:48
the AC amplifier, which is really in
16:50
charge of, you know, making decisions,
16:52
making things happen within the HVAC
16:55
system, including controlling the
16:56
compressor. And they had replaced the
16:59
AC amplifier with a used one because
17:01
when he unplugged the AC amplifier,
17:04
he said, then you can no longer
17:06
control the HVAC, the screen went off
17:08
and the drain from the battery went
17:10
away. Now that is somewhat normal,
17:13
right? If you had the car on and you
17:15
unplug the AC amplifier, the screen
17:17
would go off and it would stop
17:18
working. But it seemed to be that
17:20
there was something to do with that
17:22
module, but replacing it didn't do
17:24
anything. It had the exact same
17:25
situation even after a placement.
17:27
But it was a good direction for me
17:30
to start with is like, maybe I
17:31
should be looking at this, you
17:33
know, what changes does unplugging
17:35
the module really get rid of the
17:37
problem? Or is it just disabling
17:39
enough stuff because that module,
17:42
you know, operates a number of
17:44
things within the HVAC that seems
17:46
like the problem is gone. That's
17:47
what I have to determine on this
17:48
one. Scan it. No useful codes in
17:51
it. When the key is on, everything
17:54
seems to work the way it should.
17:56
But of course you have a bunch of
17:57
stuff working that you wouldn't
18:00
expect it to all the key is off.
18:01
So I go to the AC amplifier,
18:03
which is in the center console
18:06
area near the accelerator
18:08
pedal. And I start looking at
18:10
the circuits that are connected to
18:12
it. And it's pretty straightforward
18:14
as far as how this thing actually
18:16
gets powered up and operates.
18:17
It's got a constant battery feed,
18:20
obviously a ground, and then it
18:22
has a switch technician feed.
18:23
And that's it. And so that switch
18:25
technician feed needs to have
18:27
power in order for this module to
18:28
turn on. If that switch
18:30
technician feed is off, that module
18:32
should not be on. And OK, so
18:34
it's a blue wire. I checked the
18:36
blue wire. It has power when the
18:38
key is off. That's why this is
18:40
on. OK, well, that should be pretty
18:41
straightforward. Now, where does that
18:43
come from? And why does that
18:45
power on there? That's the next thing
18:47
that I have to figure out. So go to
18:49
the diagrams right there, shows
18:51
it as the heater ignition fuse
18:53
in the fuse box that's right
18:55
there underneath the dash. It's a
18:57
10 amp. And of course, that has
18:58
power as well, along with this
19:02
question now is, is power
19:05
being fed to this fuse
19:08
and then to the module and the
19:10
other things that this fuse
19:11
actually powers. There is four
19:13
different legs off of this
19:14
heater ignition fuse. It goes
19:16
to the control assembly on the
19:19
dash. It goes to the AC
19:22
amplifier. It goes to the
19:24
compressor relay and a couple
19:27
other relays under the hood as
19:28
well. So this powers up a few
19:30
different things. It's not just
19:32
the AC amplifier. And so that's
19:34
what I'm trying to figure out.
19:34
It's like, OK, I have power on
19:36
this fuse when the key is off.
19:38
Now this fuse gets fed from
19:40
an ignition relay, which is
19:44
fuse box that's under the dash,
19:46
right? So it's like a junction
19:47
block. And it does have like
19:52
plugged into it. But the box
19:54
itself isn't a module, but it
19:56
has internal relays.
19:57
And one of those internal
19:58
relays is an ignition relay
20:01
that is controlled by the
20:02
ignition switch and then sends
20:04
power to this fuse when the
20:06
ignition is turned on.
20:08
So that's my question. OK, is
20:09
power getting fed to this fuse
20:11
and then going to these
20:15
something on that circuit,
20:18
one of those four legs
20:19
shorted to power and power is
20:21
backfeeding to everything else
20:23
keeping it on. It's one of
20:24
those two options. So that
20:27
is fairly easy to figure out
20:29
in a situation where you have
20:30
a fuse and it has power on
20:32
it when you would expect
20:33
there to not be power on it.
20:36
Pull that fuse in the state
20:38
where you would expect power to
20:40
not be on it key off and
20:42
then check both sides of the
20:43
fuse. Right. So what I mean
20:45
by that is you have two
20:46
terminals once you remove that
20:48
fuse and you can use your
20:49
test light and figure out.
20:51
OK, do I power on one or
20:53
both sides? You probably are
20:54
only going to have it on one
20:56
side. And then you could
20:57
turn the key on because you
20:58
might say, well, I don't
20:59
know which side this goes
21:01
to. But you could figure it
21:03
out with the test light.
21:04
Right. I could go over to my
21:05
AC amplifier and that
21:07
leg that comes out of the
21:09
fuse is going to go to pin
21:11
one. It's a blue wire.
21:13
If I remove the fuse, do I
21:14
still have power on that blue
21:16
wire? OK, if I do, I
21:19
know for sure it's not
21:20
coming from the ignition
21:21
switch. And then I can go
21:22
up to the fuse. I can test
21:24
both sides. One should have
21:26
That's probably the ignition
21:28
feed side. I could turn the
21:29
key on and then I should have
21:31
power on both sides of the
21:32
fuse, right? So you can use a
21:33
little bit of logic there to
21:35
figure out, OK, that side of
21:36
the fuse goes to the
21:38
components. That side of the
21:41
ignition relay, which again
21:42
is internal to this fuse
21:44
box. So I figure that out
21:46
and it is on the component
21:48
side. OK, so key off, got
21:50
power on the fuse, remove
21:52
it and everything stays
21:54
on at that point. Even if I
21:56
pull that fuse that does
21:58
not disable DHVAC system.
22:00
So I mean, right there, you
22:02
know, even without using a
22:03
test light that like, OK,
22:07
shorted to this circuit
22:08
somewhere somehow. But I got
22:10
power on the component side
22:13
of that fuse. I have power at
22:14
my AC amplifier. And I'm using
22:16
that kind as a test just
22:17
because it's easy to access.
22:19
And I'm just back probed
22:20
into that wire right at the
22:22
AC amplifier. Now, like
22:24
he said, if you unplug the
22:25
AC amplifier, it seems like
22:26
everything turns off. And I
22:28
verified that I unplug the
22:30
AC amplifier and I no longer
22:32
have power on that blue wire.
22:34
OK, so fuse could be out, fuse
22:36
could be in doesn't matter at
22:38
this point. I put everything
22:39
back in. But I have power
22:41
on that blue wire as long as
22:42
the modules plugged in. I
22:44
unplug the module, everything
22:46
shuts off and I do not
22:47
have power on that blue
22:49
wire anymore. So I don't
22:50
really need to look at the
22:51
other components and I
22:52
didn't. I'm focused in on
22:53
that AC amplifier. Now
22:55
that again, they already
22:55
replaced it with a used one.
22:57
First one did the same
22:58
thing. Is it possible? This
23:00
is a common issue with these.
23:01
I'm not sure. Is there
23:03
something else that could
23:05
be shorted that's feeding
23:07
power through the module onto
23:08
this circuit? That's a
23:10
question that you have to
23:11
ask yourself. I mean, it's
23:14
a lot of cases when you
23:16
unplug the control module and
23:17
it fixes your issue.
23:19
Sometimes it's a control
23:20
module, right? Maybe
23:22
something taken down a
23:23
can bus or in this case
23:24
where we're, you know, we
23:26
have power shorted to a
23:27
circuit, you unplug the
23:28
module, it's no longer
23:29
short of the circuit.
23:30
Maybe it's the fault of a
23:34
there's a short somewhere
23:36
that's feeding through the
23:37
module onto this circuit.
23:38
And it's something you have
23:38
to consider. How do we, how
23:40
do we figure out if that's
23:41
the case? Now what I
23:43
did here was I looked
23:45
at the circuitry on
23:47
the diagram. And of
23:48
course, I should only have
23:50
two power feeds into this
23:51
module, one constant, one
23:52
switched. But that's it.
23:54
I should not have any
23:55
other 12 volts go into
23:58
point. But when I have the
23:59
thing unplugged, if I go
24:01
across all of the pins and
24:03
just touch them with a
24:04
grounded test light, only
24:06
one of them should light up
24:07
unless I have the key on
24:08
then two of them should
24:09
light up. And like I
24:10
mentioned, when the
24:11
module's unplugged, I no
24:13
longer have power on that
24:18
is actually coming from
24:19
the module onto that
24:20
circuit, but from where.
24:21
Okay, now I do have it on
24:23
my white wire, which is
24:24
my constant. I would expect
24:25
that. Okay, that's normal.
24:26
That's not a problem. But
24:27
do I have it on another
24:28
circuit? And I do. And
24:31
actually, it's real close.
24:33
It is one pin over from
24:36
the blue wire. So the blue
24:37
ignition feed, where I
24:38
have power, I don't want
24:39
it. That's pin one. And
24:41
pin two is a light green
24:43
wire. Where's that go?
24:44
That goes right to the
24:46
compressor. Okay. So this
24:49
is the power feed. And
24:50
it's a solenoid plus.
24:52
But this is the power
24:53
feed to the compressor
24:54
solenoid that the AC
24:57
amplifier is going to use to
24:58
operate this thing. Now,
25:00
there should not be power on
25:02
this wire unless the AC
25:04
amplifier is sending it
25:06
there. But for some reason
25:07
there is. And this is module
25:09
unplugged, right? So pin two
25:12
light green goes straight
25:13
to the AC compressor. I've
25:16
got power there. Then you
25:18
plug it in. I still have
25:19
power there. And then I
25:20
also have it on the blue
25:21
wire. So my guess is here
25:23
that this power that is on
25:25
this wire should not be
25:28
diagram. A solenoid on
25:29
compressor shouldn't provide
25:31
that. But it is and it's
25:33
backfeeding through the
25:34
module onto the ignition
25:36
circuit, which is keeping
25:38
the HVAC system awake.
25:39
Okay, so now I figure out,
25:40
okay, why do I power on
25:41
there? And I go immediately
25:43
to the compressor once I
25:44
see this. And turns out
25:46
it's already unplugged. And
25:47
I asked him, he's like,
25:48
compressor? He said, yeah,
25:50
it was one of the things I
25:51
was looking at to see if
25:52
it had anything to do with
25:53
it. And I just left it
25:54
unplugged. Okay, so
25:56
compressors unplugged and I
25:58
got power there. So it's
25:59
compressor itself. And I go
26:03
to the light green wire on
26:04
the compressor with my test
26:06
light and I don't have
26:07
power there. So I double
26:08
check the diagram I
26:09
actually pulled up the OE
26:10
diagram. I had a Toyota
26:12
sub. So I used Toyota
26:14
service information to
26:15
make sure that like the
26:17
diagram wasn't wrong. And
26:18
it's the same color
26:19
wire. But I look, okay,
26:22
this is this is the wire pin
26:26
compressor on this circuit.
26:27
But I have power at the
26:29
module, but I don't have
26:30
power at the compressor.
26:32
Well, there's two other
26:33
connectors in this circuit
26:35
between the AC amplifier
26:37
and the compressor. So I
26:39
connectors, and then I
26:40
can break up the circuit
26:41
and figure out, well,
26:42
number one, why do I
26:43
power one spot, not the
26:46
there an open and a
26:47
short? That's what it
26:48
would seem to be unless I'm
26:49
still misunderstanding the
26:50
diagram. But let's go to
26:52
these connectors, break it
26:53
down, see what we can
26:54
find. So there's a six,
26:56
which is located under the
26:58
dash on the passenger
26:59
side, just before the
27:00
harness leaves the cabin
27:02
to go under the hood. And
27:03
there is BA two, which is
27:05
actually located in the
27:06
underhood fuse block. And
27:08
these are both pretty
27:10
easy to access the one
27:11
under the dash, you just
27:12
have to reach underneath
27:13
there. Finding them was a
27:14
little bit of work, but
27:16
once I found them, they're
27:16
easy enough to access. So
27:19
a six under the dash, I
27:22
unplug it, and I have
27:24
power on the side that
27:26
goes under the hood, right?
27:28
So this is a connector
27:30
between the AC amplifier
27:31
and the compressor under
27:33
the dash, I unplug it. And
27:35
diagram, you can see the
27:36
male female side on the
27:38
diagram. So you know
27:39
which direction you're
27:40
going, right? If I touch
27:41
it with a test light, it
27:43
lights up on the female
27:44
side, I look at the
27:45
diagram, female side goes
27:47
towards the fuse box and
27:49
the compressor. And I power
27:51
there. Okay, so I need to
27:52
go under the hood. So I
27:53
look under the hood, there
27:54
was evidence of rodents
27:56
being under there. They
27:57
had chewed away some of
27:59
firewall. They had a
28:00
little nest underneath
28:02
the intake. So right
28:05
there, and I think the
28:06
tech had even mentioned, he
28:07
noticed that there was
28:08
some evidence of rodents
28:09
under the hood. But I
28:11
follow the harness, it
28:12
leaves the firewall, goes
28:13
across the firewall, goes
28:15
under the air box, and then
28:16
over to the fuse box. And I
28:18
look it over and I don't
28:19
see any evidence of the
28:21
rodents actually damaging
28:23
the harness there. Now, it
28:24
could be underneath
28:25
something, maybe I don't
28:25
see it, but it's not
28:27
visible in the part of
28:31
the harness that I can
28:32
see. So then I go over
28:34
to BA2 connector, which
28:35
is in the under hood
28:36
fuse box. I disconnect
28:39
power on either side. Okay.
28:41
So somewhere between that
28:44
connector under the dash
28:45
and the fuse box, I not
28:47
only have an open, but then
28:49
I have a short to power on
28:51
the side that goes towards
28:52
the cab of the vehicle. And
28:55
this is where we were
28:56
talking about it. And I was
28:57
like, Hey, I think we
28:58
should pull this fuse
28:58
box up and look underneath
29:00
it because it's very
29:01
strange that I have a
29:03
short to power and an
29:07
yanked up the fuse box
29:08
which took a little bit
29:09
of work to pull some
29:10
things apart to get
29:11
underneath there. And as
29:12
soon as he did, he found
29:14
at the bottom that light
29:15
green wire had been chewed
29:16
along with another wire
29:17
which had constant power
29:19
on it. And it was touching
29:20
that one. So basically it
29:22
opened it up in the
29:23
direction of the compressor,
29:25
but it shorted it to power
29:27
in the direction of the
29:28
AC amplifier. And that
29:31
wire having constant
29:32
power, the power wire
29:36
solenoid backfed through
29:38
the AC amplifier onto
29:40
the ignition circuit, which
29:41
kept that module and the
29:43
screen and everything with
29:44
the HVAC activated, even
29:46
when the key was in the
29:48
off position. So again,
29:50
rodent damage. Will I ever
29:51
see that problem again?
29:52
Probably not. I mean, I
29:54
guess it's good to know
29:56
that that sort of thing
29:57
can happen. And that's
29:58
what I'm taking away
29:59
from it is when you
30:00
have something like
30:02
shorted on a wire, you
30:03
unplug a module, it gets
30:05
rid of it. It's not
30:06
always the module, right?
30:07
It can be another circuit
30:08
connected to that module
30:09
that is not normally
30:11
supposed to have power,
30:12
but it does. And that's
30:14
going to backfeed through
30:15
other circuits. So just
30:17
be aware of that. If you
30:18
get to a part of like, hey,
30:19
this module is bad. I think
30:21
it's the cause. Double
30:22
check, use some logic.
30:24
diagram, like, okay, which
30:26
wire should I have power
30:28
on? Do I have power on
30:29
those? Do I have power
30:30
on any other ones? If I
30:32
do, and I don't expect
30:34
power to be there, why
30:35
is there power there? And
30:36
could that be causing
30:37
my problem? Same thing
30:39
ground, right? Where you
30:41
could have five volt
30:43
reference shorted out
30:45
that's taking down a
30:46
control module, preventing
30:47
it from talking. And we've
30:50
talked about it before
30:51
where, you know, you have
30:52
a whole network taken
30:53
down because of a module
30:55
that has a bad ground,
30:56
right? We remove that
30:58
module from the network
30:59
and now I can talk to
31:00
everybody else. But you
31:01
plug that module in and
31:03
anything. Or is it the
31:04
module? Okay, is it
31:05
potentially a, you know,
31:07
a bad ground to that
31:09
module that's causing
31:10
that to happen? It does
31:10
happen, right? So I guess
31:12
it's just a good reminder.
31:14
But those mice, those
31:16
rodents, they definitely
31:16
keep you on your toes
31:18
because you're going to
31:19
see these unique one-off
31:20
problems that you can't
31:23
failures to find. You just
31:25
have to use your, you
31:26
know, basic electrical
31:28
diagnostic skills in
31:29
order to get to the
31:30
solution. So I thought
31:32
interesting. Wanted to
31:32
share it. That's all
31:34
I got for this week.
31:35
Thank you so much for
31:36
appreciate it. But with
31:37
that out of the way,
31:38
let's get out there,
31:39
start fixing the world