Ron Ananian, The Car Doctor - Classic Car Doctor - October 3, 2015 - Hour 1 - The Yukon That Only Failed on the Bumps

The 2003 GMC Yukon is a full-size SUV closely related to the Chevrolet Suburban platform. In this episode, it’s notable because a bump triggers electrical issues like door locks cycling, dashboard lights flickering, and even the engine shutting off before restarting.

The Chevrolet Suburban is a full-size SUV built for hauling people and cargo, typically with a long-wheelbase layout and strong towing capability. It often comes up in discussions because it’s a common family and work vehicle, so owners frequently report recurring wear items and maintenance concerns. In a “Car Doctor” style conversation, it’s the kind of vehicle where specific complaints can point to predictable maintenance needs.

A communication fault code means the vehicle’s electronic modules aren’t talking to each other correctly. Modern cars use a shared network (often called a data bus) so sensors, computers, and body modules can exchange messages.

“U1360” (spoken as “U thirteen sixty”) is a U-code that indicates a network communication problem between modules. The host ties it to the idea that the data bus is being interrupted, which can cause symptoms like flickering lights and modules cycling when the wiring connection is disturbed.

A data bus is the vehicle’s internal wiring/network that carries messages between electronic control modules. If the data bus is interrupted (for example, by a loose connector or damaged wiring), modules can lose communication and may enter fault or shutdown/restart behavior.

A wiring harness is the bundled set of wires and connectors that distributes power and signals throughout the vehicle. When a harness wire degrades (like breaking down from many strands to one), it can cause intermittent communication faults or shutdowns because the electrical signal can’t carry reliably.

The intake manifold is the ducting that routes air (and often fuel/air mixture depending on the engine design) from the throttle/intake system into the engine’s cylinders. Ground points located “at the back of the intake manifold” are hard to access, which can make the fault difficult to diagnose.

In automotive diagnostics, “ground” refers to the electrical return path that completes circuits. Ground problems can cause weird faults like communication errors, intermittent shutdowns, or sensors/radios acting up because the car can’t reliably reference the same electrical baseline.

In diagnostics, “Murphy’s law” is a shorthand for the idea that the hardest-to-reach or least-obvious location is often where the real problem is. The host uses it to explain why he focused on hidden ground points that were difficult to see or repair.

“Ground 103” (G103) is a specific labeled chassis/engine ground point used in wiring diagrams. Mechanics test these named grounds because a failure at one exact location can create a repeatable set of electrical symptoms on that vehicle generation.

The bell housing is the housing between the engine and the transmission that contains the connection area (like the clutch/torque converter depending on drivetrain). Reaching into the “bell housing area” suggests the mechanic was working around the engine-to-transmission wiring/connection space where certain harness wires and grounds can be routed.

“Vehicle computer” refers to the electronic control units that manage vehicle functions. In this segment, the speaker ties the vehicle computer’s failures specifically to the PCM losing ground, which then causes cascading electronic glitches.

PCM stands for powertrain control module, the car’s main computer for engine and transmission-related functions. When the PCM loses a critical ground, it can reset or shut down, which can trigger odd behavior across the vehicle’s electronics.

General Motors (GM) is the automaker whose truck platform the speaker says had the ground-related PCM fault. The point is that this kind of intermittent “ground” issue can be tied to specific GM wiring design choices on older vehicles.

A “bumpy road” can create intermittent electrical faults by flexing wiring and connectors. Here, the speaker describes a ground wire that flexes enough to break contact intermittently, causing the PCM to cycle and the vehicle to do unpredictable things.

A “wiring loop” is extra slack engineered into a harness so the wire can move with the engine and chassis without being constantly tensioned. The speaker argues that adding a loop prevents the new wire from breaking because it reduces stress as the engine shifts and twists while driving.

This segment is a discussion topic about Powerframe’s grid technology and batteries. It’s positioned as a future conversation in the next hour rather than a deep dive into a specific car system.

General Tire is mentioned as the source of a later segment about “entire technology” in the bottom of the hour. This excerpt doesn’t provide technical details, but it signals a tire-technology discussion coming up.

A coolant exchanger is a service tool that replaces old coolant with new coolant more completely than a simple drain-and-refill. Without one, a lot of old coolant can remain trapped in the engine block and cooling passages.

Motor Medic is the brand of a fuel-system cleaning product the host recommends for DIY use. He claims it can clean both the fuel and intake portions of the system and is sold through O’Reilly Auto Parts.

O’Reilly Auto Parts is the retailer the host names as a place to buy the Motor Medic cleaning product. This is relevant because it’s part of the “where to get it” guidance for the recommended fuel-system cleaner.

A fuel system cleaning kit is an aftermarket product used to remove deposits from parts of the fuel delivery system. In this segment, it’s described as cleaning both the fuel side and the intake side so it can reach areas like the intake manifold and valves.

“Tranny fluid” is the transmission fluid that lubricates internal transmission parts and helps the transmission operate smoothly. Over time it can degrade, so the host argues that it’s still worth doing a draining-and-filling service rather than assuming it never needs attention.

A 2009 Toyota Corolla is a mainstream compact car that uses an automatic transmission in many trims, and the discussion here is specifically about transmission fluid service. The key point is that the owner never changed the transmission fluid, and the host explains why that “lifetime fluid” idea may not be realistic.

A “draining fill” is a transmission service where you drain out some of the old fluid and refill with new fluid, rather than doing a full flush. The host frames it as the practical way to refresh fluid even when the car is marketed as having “lifetime” fluid.

A “dipstickless vehicle” is one where the transmission fluid level can’t be checked with a traditional dipstick. The host notes that even without a dipstick, the fluid service is still doable, and in this case the owner has a dipstick, making it easier to verify the level.

“Original equipment Toyota” means using the manufacturer-specified fluid (or an equivalent that meets the same specification) for the transmission. The host recommends sticking to Toyota’s fluid or a correct equivalent so the fluid’s properties match what the transmission was designed to use.

“RAF four” is almost certainly the Toyota RAV4, and the host is saying that if you haven’t changed its fluids, you should consider replacing them too. The underlying concept is that fluids have a finite service life, even if marketing implies they last forever.

The host’s “finite life” point is that automotive fluids degrade with heat, time, and use rather than lasting indefinitely. Even if a manufacturer markets a fluid as “lifetime,” the practical reality is that refreshing it can help maintain transmission performance and longevity.

The Toyota FJ Cruiser (2008) is a body-on-frame SUV built around a rugged, off-road-focused layout and a strong low-speed drivability reputation. In this episode, the owner describes a shaking/chugging behavior specifically in Drive at low speeds, which points to a driveline or gearing/load issue rather than a general engine problem.

An automatic transmission changes gears by itself using hydraulic pressure and electronic controls, instead of a driver operating a clutch and shifter. In this case, the shaking only occurring in Drive helps narrow the diagnosis toward how the automatic is selecting gears or how the drivetrain is loaded at that speed.

A “lifted” vehicle has been raised higher than stock, usually with suspension lift components and often larger tires. Lifting changes driveline geometry and effective gearing, which can cause drivability issues like vibration or shudder if the rest of the setup (tires, gearing, angles) isn’t matched.

The pinion is the small gear in the differential that meshes with the ring gear to transmit power to the axle. When a vehicle is lifted and/or fitted with larger tires, the effective gearing changes; if the differential gear ratio isn’t adjusted accordingly, you can get symptoms like shuddering, lugging, or vibration under certain speeds and throttle/load conditions.

A differential is the drivetrain component that lets the wheels on an axle rotate at different speeds, which is crucial when turning. In a vibration/angle discussion, people often suspect the differential’s mounting position or how it aligns with the driveshaft.

The driveshaft (drive shaft) transfers torque from the transmission to the rear axle in many rear-wheel-drive and four-wheel-drive layouts. If the rear differential or axle is shifted, the driveshaft can run at an “odd angle,” which can cause vibration.

In driveline diagnostics, “coasting” refers to driving without applying fuel (lift-off) so engine torque is reduced or removed. Comparing vibration behavior under throttle vs coasting helps determine whether the issue is related to torque load or driveline geometry.

Four-wheel drive (4WD) sends power to both the front and rear axles, typically using a transfer case and additional driveline components. That extra driveline complexity can make vibration diagnosis depend on which gear/speed/load condition is triggering it.

A transfer case is the gearbox in many 4x4 vehicles that splits engine power between the front and rear axles. It’s what enables low-range gearing and, depending on the drivetrain design, can route power to different wheels.

“Drive shift” here appears to be a mis-transcription for “driveshaft,” the rotating shaft that carries torque from the transfer case to an axle. The context is about removing the shaft to see if the problem changes.

Tire balancing is the process of matching weights to the tire/wheel so the assembly rotates smoothly. If tires aren’t balanced, they can cause vibration that may be mistaken for drivetrain or suspension problems.

A bent wheel rim can cause vibration and uneven tire wear because the tire can’t rotate concentrically. It’s a common cause of shaking that can be confused with driveshaft or suspension issues.

Suspension is the system of links, springs, and dampers that controls how a vehicle rides and how its wheels stay aligned with the road. When diagnosing driveline issues, suspension condition can matter because it affects axle angles and how components load under movement.

The Cadillac SRX is a late-model Cadillac crossover that, in this context, is described as using GDI (gasoline direct injection). GDI sprays fuel directly into the combustion chamber, which can lead to carbon deposits on intake valves—so fuel-system cleaners are marketed to target that buildup.

GDI (gasoline direct injection) is a fuel-injection system that sprays gasoline directly into the engine’s cylinders instead of into the intake tract. Because fuel doesn’t wash over the intake valves like it does in older port-injection designs, carbon deposits can build up on the intake valves over time.

Gasoline direct injection describes an engine design where fuel is injected directly into the combustion chamber. This can change how carbon forms, especially on intake valves, which is why some fuel-system cleaners are specifically marketed as being effective for GDI engines.

An intake valve is the engine’s valve that opens to let the air-fuel mixture enter the cylinder. In GDI engines, carbon deposits can be more likely to accumulate on intake valves, which is why certain cleaners are advertised as attacking those deposits.

Carbon deposits are soot-like buildup that forms inside engines from combustion byproducts. In GDI engines, carbon can accumulate on intake valves, which can affect airflow and drivability—so cleaners are marketed to dissolve or loosen that buildup.

Paint bubbling typically indicates trapped moisture, contamination, or poor surface preparation that prevents the paint from bonding correctly. In bodywork, bubbling can also appear when the underlying surface wasn’t properly cleaned, sanded, or primed before the topcoat was applied.

“Belt shifted” refers to internal tire construction belts moving out of their intended position. Those belts help keep the tire’s shape and tread uniform, so a shift can lead to abnormal wear, vibration, or premature failure. In the context of the story, it’s used to explain why a tire can “go bad” even if it was sold only a year earlier.

The “cord” is part of the tire’s internal reinforcement structure. When the cord is damaged—often from impacts like potholes or curbs—it can create a visible failure point and lead to issues like bulges or separation. The host emphasizes that you can usually find a physical “mark” that matches the damage source.

A pothole is a road surface defect that can create a sharp, high-impact hit to a tire or wheel. That kind of impact can damage internal tire components (like belts or cord) even if the outside looks only mildly affected. The host uses potholes as a common cause of “where the mark” comes from.

“Paint to adhere” means the paint needs a surface that bonds properly so it doesn’t peel or fail prematurely. If the old bumper is weathered or damaged, the paint may not stick well, leading to a redo. The host’s advice is to consider replacing the bumper if surface condition will compromise adhesion.

The “aftermarket” is the network of companies that make replacement parts not supplied by the original automaker. When a new factory part is hard to find, aftermarket suppliers (including body-part specialists) can often provide compatible replacements.

“Non original equipment parts” are aftermarket replacement parts that aren’t made by the vehicle’s original manufacturer. Body shops and insurers may use them to reduce cost while still repairing the car to be road-legal and cosmetically correct.

In collision repair, insurance companies often influence which parts get used and how repairs are approved. Their cost-control incentives can lead to selecting aftermarket or non-original parts instead of factory replacements.

A 2005 Dodge Durango is a mid-size SUV from Dodge that uses a conventional drivetrain layout with an engine and transmission. In this story, the key issue is that the engine failed and the repair required additional parts to make the vehicle drivable again.

A ground wire provides an electrical path back to the vehicle’s chassis/negative side, which is essential for sensors, modules, and lighting to work correctly. If a ground wire is pinched or misrouted, it can cause intermittent faults or prevent systems from functioning reliably.

A shift cable is the linkage that connects the driver’s column shifter to the transmission’s internal shift mechanism. If the shift cable breaks, the driver may not be able to select gears normally, which is why the Durango can’t be made fully drivable.

A column shifter is a gear selector mounted on the steering column rather than on the center console. In vehicles that use a shift cable, the column shifter’s movement is transmitted to the transmission through that cable.

A back order means the part is not currently available for immediate sale and must be produced or shipped later. This episode uses it to explain why the Durango can’t be finished: the shift cable is on national back order from Chrysler.

Chrysler is the automaker responsible for the parts supply chain referenced here. The host says the shift cable is on national back order from Chrysler, highlighting how OEM (original equipment manufacturer) inventory affects repair timelines.

EVAP (evaporative emissions) systems route fuel vapors from the gas tank to be burned in the engine instead of venting to the atmosphere. EVAPP here refers to an EVAP-related fault/monitoring code that points to a problem in that vapor-control system, often involving the tank, lines, or valves.

Fuel treatment is an additive you put into gasoline to help it stay stable during storage and reduce issues like oxidation and gum formation. In this context, it’s being used to keep the fuel from degrading while the car sits or is only driven intermittently.

Premium refers to higher-octane gasoline. Higher octane helps prevent knock (detonation) in engines that are designed to use it, and it’s often recommended when an engine’s tune or compression makes lower-octane fuel less suitable.

Moisture is water contamination, and it can be a major problem for stored vehicles because it promotes corrosion and can lead to water collecting in places like the crankcase. Here, the host points to moisture as the main enemy when the car isn’t used regularly.

“Water laying up there” describes condensed water that collects under the valve covers. Condensation can happen when temperatures cycle, and it’s especially concerning because it can mix with oil and accelerate corrosion inside the engine.

Valve covers are the housings on top of an engine that protect the valvetrain and seal in oil. Removing them lets you inspect for issues like condensation or sludge, which can indicate moisture problems when a car sits.

Fuel system cleaner is an additive designed to clean deposits in parts of the fuel system, such as injectors and intake passages. The host suggests adding it while driving on premium fuel to help keep the system cleaner over time.

A tread cushioning system is a tire design feature intended to reduce road noise and soften harsh impacts. In this segment, it’s cited as part of why the newer HTS sixty tire should provide a quieter ride.

Tread life is how long a tire’s tread compound and grooves are expected to last before wearing down. Here, the host claims the HTS sixty has “twenty five percent better tread life,” implying longer-lasting grip and usability.

The Honda Pilot is a midsize SUV from Honda, known for family-friendly space and comfort. In this segment, it’s mentioned as the specific vehicle Chris wants to prepare for winter, so the tire choice matters for grip and ride quality.