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324: Did You Try Unplugging It & Plugging It Back In?
324: Did You Try Unplugging It & Plugging It Back In?
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About this episode
Exploring the surprisingly effective diagnostic technique of fully disconnecting and resetting vehicle control modules, this episode dives into real-world cases where a battery disconnect or module unplugging resolved persistent warning lights and error codes. From a Chevy Colorado's stubborn check engine light to a BMW X7's rear differential warning and a complex Audi A4 component protection issue, the host shares insights on when and how a hard reset can save time and avoid unnecessary replacements. The discussion also highlights the importance of understanding vehicle electrical systems and checking for software updates or service bulletins.
Topics:
battery disconnect reset
module hard reset
capacitive discharge
component protection
diagnostic troubleshooting
software updates
BMW rear differential
Chevy chassis control module
Audi component protection removal
automotive diagnostics
We often deal with strange control module issues- codes, warning lights, communication faults, or reduced functions. While the causes are numerous for each individual situation, one thing that may "fix" the issue is a battery disconnect or capacitive discharge. I'll share 3 vehicles today where a CAP discharge was the fix for strange problems.
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Welcome to the Automotive Diagnostic Podcast.
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Hey, what's going on?
Automotive World, welcome to another episode of the Automotive Diagnostic Podcast.
My name is Sean Tipping.
I'll be your host once again for this week's episode.
Thank you so much for joining me.
Just me on a show this week, and I'm going to talk about something that I've dealt with
as long as I've been fixing cars and diagnosing module issues on cars, but have had it come
up a couple times recently on some newer vehicles that this was the solution to actually
moving forward, to getting the vehicle back to a working state, to get rid of warning
lights, codes, whatever it might be.
It's the thing that worked, even though it's very simple.
As you could tell by the title of the episode, it's a little tongue-in-cheek of if you've
ever called for tech support on anything, the internet modem at your house, or any
piece of technology like a computer or something.
One of the first things they ask is, have you unplugged it and plugged it back
in?
Of course, when those people call, I'm like, yeah, of course I tried that, even if I haven't,
but a lot of times it actually does fix the problem.
I'm going to be talking about a few instances of that here today where if you have not
tried a battery disconnect, there's different ways you can do this, but what I'm talking
about is completely removing power and ground to either a specific control module or the
entire vehicle, and there's different ways that you can do this, but to do basically
a hard reset, one of the shops I go to, they call it brain-deadding the module, and this
may also involve doing a capacitive discharge, which not only is disconnecting the battery
itself, but then touching the two cables together, so you take the positive and the negative
off the battery.
Now, keep in mind here, this is if there's only one battery.
If you have multiple batteries in a car, you need to disconnect all of them before
you do this next part, but then once disconnected, you would touch the positive and the negative
together, and that's going to drain down any reserve power that any modules might have in
some sort of capacitor or something like that, where some modules will have a setup so that
they can retain memory for a short period of time, even after the battery is disconnected,
and this is going to take care of that, so everything is going to be a full, hard reset,
brand new, just rebooting the system, if you will.
Now, again, you can just disconnect the module, and this may perform something similar, and
I'll give you an example of that, but doing the full capacitive discharge is going to
reset everything on the vehicle.
Again, you're going to need to know the electrical setup of the vehicle.
Do you have more than one battery that's connected to that system?
If you do, you don't want to take those cables off of just one battery and touch them together.
That's a problem.
Of course, there's a lot of nuance that goes into that discussion.
Basically, you need to know the electrical system on the car that you're working on before
you attempt something like this, and if you're not sure, and you've got a specific module
in question, then maybe just go after that particular module rather than the whole system.
I'll give you an example of that on a BMW that had a 48-volt system, and I wasn't in the
moment confident enough to disconnect everything in that electrical system, so I just disconnected
the module and ended up working for me.
But doing this reset can save you a lot of time, and I mean, fix the issue in a lot
of cases, instead of beating your head against the wall, trying to fix these module issues
or codes or warning lights, and nothing else seems to work.
So I'm going to run through three vehicles that I've dealt with recently where the capacity
discharge or the battery disconnect from either the vehicle or the module in question fix
the vehicle.
Now, we should mention, is it permanent?
Is it a permanent fix to whatever caused that?
Maybe, maybe not.
Is it going to happen again if your computer freezes up and you unplug it and that
brings it back to life?
Is it going to freeze again?
It might.
When is it going to happen?
I don't know.
And that's kind of where we're at with some of these situations, because this might happen
again.
We don't know.
If it does, well, OK, we may have to replace a particular module that seems to be causing
this problem or is involved with the problem.
Maybe there's a software update, and that is something that you should search for.
If this is an issue, you discover, hey, this module is having some strange fault that I can't
get rid of any other way.
And again, I'll give you some examples of that.
But either unplugging the module, plugging back in, or doing capacitive discharge on
the whole system fixes the problem, OK, is there a software update for this module?
Is there a hardware update for this module, right?
Is there a service bulletin that just says, hey, the radio screen in this GMC terrain locks
up from time to time.
We don't have an update for the software, but you have to replace it with an updated
hardware piece.
That's possible, too.
So this isn't necessarily a permanent fix.
It might be.
I'll give you the first one I talk about.
I feel like it is a good fix.
I don't think there's anything else that needs to be done in that instance.
There could definitely be a situation where, hey, a module is going to continue to have
this error, and either update or replacement is necessary.
Actually, one that does come to mind, just one that's in memory from early on when I
was a technician in the Chevy trucks of the early 2000s, they would have a memory
seat module that would just go into a logic lock, and none of the seat functions would
work once this happened.
You might not even have communication with it at that point, I'm not sure, but disconnecting
the module and then plugging it back in brought it back to life, and they had a software update
to fix that.
You could go through SPS and update that module, and that was supposed to prevent
this logic lock up from happening.
So take a look and see, because there might be a fix or there might be known information
out there to correct the issue that you're temporarily fixing with the capacitive discharge,
but in that moment, that's the only thing that's going to move you forward or get your
module or your vehicle back to a working state, so we don't want to forget about this.
And that's kind of the reason for this episode, is sometimes this is something that is easy
to overlook or not think about, hey, I should try this.
I should also mention, this shouldn't necessarily be the first thing that you do, right?
Oh, hey, this radio screen's locked up, I better disconnect the battery and see if
that fixes it.
You should do some investigative work.
Do your pre-scan, look at the modules in question, record the codes, see if doing anything else
does fix this.
But if you don't seem to be getting anywhere with the normal diagnostic methods, or here's
the other thing, you're about to call a module and say, hey, this module's bad, I've got
to replace it, and in all honesty, it might fix it because you're disconnecting that
module from the network and putting a new one in.
But could it come back to life just with a battery disconnect?
And again, sometimes that's the key.
What if it's a situation where you've already replaced the module, and now you've got something
weird going on?
So I'll tell you about that.
This is a 2016 Chevrolet Colorado.
The shop had replaced the chassis control module, which is also the fuel pump control module
with a brand new one.
And after they replaced this module and then we come in, we program it, there's a
check engine light on, and it will not shut off.
We did key cycles, full power downs with key off, which that alone sometimes is the answer.
But we waited until everything went to sleep, turned it back on, tried clearing codes.
In the ECM, we're looking for pending codes, nothing's there.
Check engine light stays on.
We end up disconnecting the battery.
And I didn't even have to do a capacitive discharge on this one.
I just disconnected the battery, reconnected the battery, check engine light is off.
That's it.
So in that case, I don't think I have to do anything else.
That might just be some glitch, some error from putting a brand new, and this is from
the dealer module in that vehicle.
And it caused the engine control module to throw the MIL on for some reason.
Hard to say exactly why.
I don't know what's going on at the module level there, but there was something about
the data that it was or wasn't getting from that module, maybe in an unprogrammed
state that caused it to just say, Hey, the lights on, I'm not shutting it off.
Would enough key cycles turn it off?
Maybe, but it was a lot quicker just to disconnect the battery, reconnect it, and we're fixed.
So now we wrote that down in our notes because odds are we're going to get another 16-ish
Chevy Colorado that needs a chassis control module programmed.
And we might be there sitting like, why is the check engine light on when there
are no codes?
And of course, the shop's going to blame us.
Hey, you just programmed this.
The check engine lights on.
You guys need to come figure this out.
And I mean, in a way that is our responsibility as the programmers to at least alert them to
that.
You need to do a battery disconnect, but we'll just do that for them in that case.
It's easy enough to do.
So one of the other ones that I dealt with recently was this episode is brought to
you by L1 Automotive Training and Keith Perkins.
If you're looking for education on module programming,
J2534, eProm work, key in a mobilizer, electrical diagnostics or drivability diagnostics,
Keith has a website L1training.com that's got over 60 hours of training videos on all
those subjects and more.
When I first started out doing mobile, I utilized Keith's videos on module
programming and J2534 in order to get my head wrapped around what I would need for
the tooling, the computers, the software setups, what kind of obstacles I would be
up against when I'm out there programming modules on cars.
And it was a huge benefit to me.
And I continue to use the training videos that he has on his website.
So I strongly recommend checking out L1training.com.
The link is in the show notes.
2023 BMW X7.
And I think I mentioned this vehicle on the, it might have been the module,
module communication episode three or four episodes ago, and I was just getting
involved with it.
And this one I burnt up a lot of time on this thing before I found out just
disconnecting the module took care of my problem.
Now, for a little bit of backstory on this one, we found my technician that
was working on it, found some open wires to that we're going from the rear
differential lock control module to the rear differential unit.
This was very obvious, very apparent that, Hey, there's some harness damage
here.
It was backed by the rear bumper.
You guys fix this and then, you know, it should be good, but if you
need to come clear codes or check it out afterwards, give us a call.
And what they were getting was a warning light on the dashboard that
said rear differential locking reduced, and that would pop up on the dash as soon
as you started the vehicle and a code in the VIP module, which is virtual
integration platform or something, something to that effect.
Um, there was a code in there that saying that the regulated locking
differential function was unavailable and this code would repeatedly set.
Now there were no codes in our rear differential control module or it's
listed on the module list as G H A S or the rear differential module.
This is in the right trunk area of the vehicle.
There was no codes in this module, but there were codes in the VIP module.
Um, that we're saying, Hey, there's, there's an issue with this.
We're shutting down functions here.
And we could not get this to go away no matter what we did, including
using it's to, and being as it was a 23, I wasn't going to rely on
aftermarket scan tools outside of, you know, our first attempts to clear codes
or to read codes.
My assumption was there's something it's going to show us that the
aftermarket scan tool didn't, or, or there's a reset that needs to happen
or a learn or something that needs to occur that the factory scan
tool is capable of that the aftermarket isn't.
That was my thought going into this one and I tried and I got, it's
the going and I wasted a lot of time trying to get this light to turn off
and nothing I did, no function.
And there were some functions in it's the, the aftermarket tools didn't
have, but no function worked.
And it showed me nothing new as far as codes or information went that
I wasn't able to see.
I was just using a top down on this thing otherwise.
And outside of a few reset functions that I couldn't find within top down is
essentially the same, exactly the same.
And I got basically nowhere with it after an hour and a half of messing,
messing with it's the most that that is waiting for the stupid thing to boot
up.
But anyways, um, I finally went to this rear diff control module and I was
going to, my intention was I was going to start checking circuits to
see if something was still open, right?
That was my assumption going into it.
It's like, well, maybe they did some wiring repair wrong and for some
reason it's not coding for it, but can I actually start measuring these
circuits and make sure that they're connected to what they need to be
connected to.
I figured I was going to find, you know, something wrong with the
repair and for some reason we're not getting a trouble code.
Well, turns out just disconnecting that module.
And I was doing that so I could do circuit checks and then plugging
the module back in, got rid of the code in the other module than it was happy.
So there was some reset that needed to happen within this rear diff module
electrically that caused everybody to be happy.
Now, if you're a BMW expert out there and you work on these things all
the time, maybe there is a different way that I could have gotten here.
But oh my gosh, I tried every single reset and relearn and clear code
option that I could find again, using the factory tool.
So I don't know that there was a different way.
Now, could I have done a full capacitive discharge on this system?
Probably, but I would have had to have done a little bit of education for
myself on the 48 volt system on this one and how that works when you
attempt to do like a full system, capacitive discharge.
Um, and to be honest, I didn't go that far on this one, just
disconnecting the module and question was enough.
But again, it's an example where you might want to be careful of
just disconnecting, you know, the 12 volt battery and putting them
together. Is that going to be enough?
Is that safe in that instance to do that?
If you only disconnect the 12 volt?
Um, hard to say because I haven't tried it.
So you'd have to do a little bit of reading on that.
And again, maybe you're an expert BMW tech listener to this and
you know the answer to that.
But that was another example of one recently where the, I wasted a
ton of time on that car trying to get the light off and disconnect
in the module and plugging it back in was the fix it reset it.
And that vehicle has been gone for several weeks now.
So it's not like it popped back up with another issue.
Um, it was good to go after that point.
All right.
Last one, I just dealt with this this week and I actually
reached out to some friends for some help on this one because
it was beating me up as well.
This was a 21 Audi A4 and this showed up to one of my
customers shops and there was no history on this car.
It was a Carvana car, right?
Somebody had purchased it from there and then now they have it.
They have a problem with it and now it's at this shop.
I have no history on anything that had been replaced or not
replaced on this vehicle prior to them looking at it, which maybe
if I did, I don't know if that really would have changed my
path, but going into it, that was my assumption is that
something had been changed on this vehicle module wise, and
that's the reason for these issues.
So let me set up what we were dealing with on this vehicle when
we got into it and then I'll get to what eventually fixed it.
So there is a series of modules on Audi vehicles where if you
replace that module, particularly with a used control module,
you will set a component protection code and the functions
for that module will most likely be locked out until you remedy
the component protection active.
That's really all it is.
It'll say component protection active and you need to disable
that using the factory scan tool, which is Otis.
I'm not aware of another tool that'll do that.
There might be something out there.
Obviously you could probably clone some of these modules
and get them to work, but as far as scan tool wise, disabling
component protection, you need an online connection using
Otis in order to remove said component protection.
Now, depending on the vehicle, that'll be different modules.
And some of them are surprising.
It'll be like a Sunroof module or an HVAC module, some
driver assistance systems like the lane departure and things
like that can set component protection.
And this is slightly different than the immobilizer system of
the car, right?
So the immobilizer is going to prevent the vehicle from
actually keying up and starting, whereas a component
protection, your vehicle is probably still going to start
and run.
And this one did, but you have certain functions that are
locked out.
And of course, the code that's present.
So it's like an immobilizer, but different.
It's kind of like a radio locked on a GM product, right?
You can still start up and drive the vehicle, but it's
just going to say radio locked until you fix the VIN number
in the radio to match the body control module.
Same same thing here, but this is Audi's version of it.
So I go in to this Audi and this 21 Audi.
And I find that there are a ton of modules that list that
they are in component protection mode.
This would be almost all of the driver assistance systems.
The lane watch camera, the front radar, both of the
blind spot modules, the emergency call module, the
instrument cluster, the HVAC module.
And there were several others as well.
I have a feeling like every module that could set
component protection was on this vehicle or I don't
know, at least it was close to it.
So I had a huge list, right?
And so now I'm wondering, I'm like, okay, well, how
many things were actually replaced on this?
Cause generally what you see is the module that has
been replaced is going to have component protection
active, but none of the other modules are.
They might code for like communication or invalid data.
You will get that, especially if the module's not
coded correctly for the vehicle, but you don't see
it where every module has component protection active.
And that's what I found on this car.
Again, not every module, but there was probably a
list of eight or nine of them that had the
component protection active.
So I go into this and I start looking at it.
And the, this was a little bit of education for me on
this exact platform of this vehicle.
The gateway module is the component protection
master in this application, meaning it is the
thing that determines if said modules belong to
the vehicle or not.
And so I really was looking at this to see, did
someone change the gateway module?
That was kind of my thought going into this is
like, oh, okay.
Well, somebody put a gateway in and it doesn't
match the vehicle.
Then yeah, we could have a component protection
active in multiple modules, but that didn't appear
to be the case.
And I actually went through each one of these
modules individually, looked at the VIN numbers,
and they all matched the vehicle.
And I mean, there's a possibility maybe
somehow, you know, the VIN number was changed,
but it still didn't belong to the vehicle.
But what I did was I tried removing component
protection on all of these modules.
And you can do this a couple of different ways.
You can go into the individual modules and, you
know, run a component protection removal function.
It builds it in a test plan for you in Otis,
actually, or you can go to the gateway and you
can basically remove component protection on
everything.
I tried it both ways.
And here's the thing.
It said successful every single time I tried,
if I tried it individually on a module,
said successful.
If I tried it on the gateway and it ran
through everything, which does take some time.
So be aware of that.
It said successful on every single module.
I even tried running the replace control module
for the gateway.
And I was, as I'm doing these things, I'm like,
okay, am I going to make the situation worse?
Because that's totally possible.
You start running functions on modules when maybe
they've been replaced, or you don't know
which one was replaced, and you could make
the situation worse.
But at this point, I'm like, well, I'm
going to try it and see what happens.
So I did the replace module function for the
gateway, all successful.
It did the component protection removal again,
you know, codes the module initializes the
module, all that stuff.
And same thing, same problem.
All these modules still code the same way.
All the functions are limited.
You can see I was using the instrument cluster
as my immediate indicator, because it would
just say a safe CP and it was just component
protection and the eight like the HVAC module
wasn't turning on.
It was just blinking one of the lights.
So it's very obvious that nothing changed here.
So I get a log from this thing after I spent
a bunch of time on it, trying to figure
out what was going on.
And I send it to some friends and I'm
talking to some other people.
And while I was leaving the shop, I told
them, hey, why don't we do a battery
disconnect on this thing overnight?
You know, do the capacitive discharge on it
and we'll come back tomorrow.
It was actually a couple of days for me
until I could get back there and we'll try
again, but a hard reset might be a good
idea in this case, you know, and should I
have done this sooner on this vehicle
potentially, but I had them do that.
I talked with some friends about some of
the stuff and we had some ideas and
some things to look at.
But I came back a couple of days later.
And the first thing I tried after we
did connected the battery again was I
did the component protection again and I
was actually looking to get some
information specifically from the log
when that happened.
That was going to be my, you know, idea
of where I was going with this.
I actually, what I did was I took the
log and I because if you've ever
used Otis, you get this, you can do
the long log, which just documents
like everything you've done on that
car, every button you clicked, all the
background processes that happen that
you're not necessarily seeing and all
the information for it and it makes
this like depending on, you know, how
much you do on the car, like thousand
page document that has all kinds
of data and you can search through it.
But I was using chat GPT that helped
me like kind of summarize like, hey,
can you find specific points within
this log where we're attempting to
do component protection removal?
Do you see airs going on here?
You like help guide me to the
part of this log that I need to
look at that's, you know, showing
what the actual problem is or if
it's successful and I was going to
try to break it down that way.
But here's the deal.
It worked after I did it that
second time.
And this was after the battery
disconnect and I have a
fueling that was the key because
I tried all of this multiple times
prior and then as soon as we did
about battery disconnect and I did
it again, it was all good.
Everything was happy.
Nobody was upset.
No codes, no lights, no warnings.
I, you know, powered it down and
fired it back up multiple times,
ran, you know, a full system scan.
Everybody's thumbs up ready to go
and everything works on the car.
Like, okay, so, um, and I
had also looked for TSBs for
software.
Interestingly enough, there was
one for a newer Audi is like a
23 where there is a software
update to the comfort control
module, which is BCM2 that
can cause similar problems.
But they give you an SVM code,
which if you've never used Otis,
if you want to do like a software
update on a module, you need to
or one of the ways to do it is to
input a code from a service
bulletin and I tried that.
I was just like, well, let's try
it and it said it didn't apply to
this one.
So not a fix, but like I
mentioned at the beginning of
the episode, you want to look
for service bulletins, known
problems, um, any references to
like, hey, there might be a fix
for this type of thing happening
and, you know, it's a 21.
Maybe they still come out with a
TSB at some point.
Maybe it's a replacement of a
gateway.
Maybe it's something to do with
the comfort control module.
Um, it, you know, it did mention
in my research that one of the
two modules that could really
cause, you know, widespread
component protection codes to
set is either the gateway or
the comfort control module BCM2.
Like those are the two main
players that could potentially
cause this and the TSB for
the 23, uh, kind of validated
that, that BCM2 is a
possible contributor to this.
So which module did I reset
with the capacitive discharge
that allowed me to actually get
everything to work properly?
Hard to say.
I don't know.
Um, I guess this is one of
those two modules, but if I
run into a situation like this
again on a newer Audi vehicle
like this, you know, that is
one of the things that I'm
going to be trying.
Of course, I'm going to look
at everything, document what
codes I have.
Um, you know, that's really
important.
So you have the documented
information of what was there
when there was a problem
cause you're going to lose
all that when you do your
capacitive discharge, but try
it, try on plugging it and
plugging it back in and see
if that fixes your problem.
You'd be surprised a lot of
the time.
So hopefully you found that
interesting.
Maybe it's just a good
reminder in your process to
have that as one of the
steps that you do.
If you're running into some
weird issues that just seem
to be putting you into
circles, but that's all I got
for today.
Thank you so much for
listening.
Always appreciate it.
Let's all get out there.
Start fixing the world.
One car at a time.
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