Seriously, the reasons why I don’t want to perform the replacement of mechanical devices is two-fold; first, I get bored easily — so the tasks I perform become “tedious boredom” when all I’m doing is trying to get them done faster than the last time I did the same thing and secondly, I’m no longer physically able to do what I used to be able to do. Maybe it’s because I did what I did when I was able to, with disregard for how I’d eventually PAY for doing them in the future, is why my body has fallen apart? It’s as good a guess as any. So, it’s diagnostics and ONLY diagnostics for me now and in my future, sanity be damned!
There have been many people credited with coining the phrase “The definition of insanity is repeating the same mistakes and expecting different results.” There are many variations of that often-repeated statement and they all seem to apply most appropriately when we are diagnosing problem vehicles! How many times have you thought “Did I miss something in my diagnosis?” It’s that question which I kept repeating recently while I was diagnosing a 2005 Chrysler 300 LX with a 5.7L Hemi, AWD and 80,985 miles on the odometer. Have you ever had to re-do the diagnostics you performed previously because a problem is still present?
Starting with the customer’s notes
As was the case with this vehicle, we aren’t always fortunate enough to be able to review repair history. Jeff and Katie had purchased the vehicle five months before bringing it to Gary’s shop. They said it had only recently developed the symptoms regularly when at first, they were happening only sporadically. As described by a written note left in their vehicle, the symptoms included “drives rough — jumpy — all the time, worse when wet.” They went on to describe them further by writing “does sometimes cut out when stopped. Not running on all cylinders. Spark plugs replaced 2 months ago — problem is worse.” Lastly, it was written “Get random misfire errors.” I just love customers’ notes. Don’t you?
Do you ever get the feeling someone has been working on a car, recently, like right before the customer brought it to YOU? That’s the way I interpreted what was written. Is that what you thought too? My curiosity was peaked around HOW the customer knew there were misfire codes. Also, I had to believe the REASON the spark plugs were replaced was to (guessingly) resolve the misfire(s) because the cause could not be determined. Obviously that work made things worse (or did it?). Did rainy weather have an effect before the spark plug replacement or did this operation create a new problem? I also wondered WHO replaced them (a professional or amateur?). Lastly, what was meant by “sometimes cut out when stopped?” It was my responsibility to determine the causes of these complaints.
I preach about the need for your first step to be a visual inspection, which is where I started on this vehicle. Until this one, I’d never worked on a 4WD Chrysler product that didn’t have “33 inch Mudders” and wasn’t extensively modified for off-road use only! This was a new one on me so I was particularly observant!
The first thing I noticed was a much-labored starter when cranking the engine. There was a noticeable “starter drag” but the engine did eventually start. Once running, a light tapping sound was heard, which went away after a few seconds. The lead tech and I went out for a test drive. We noticed a loud “rubbing” noise, similar to a tire rubbing the inside wheel well as we backed into the parking lot to leave. It went away as we took off. No misfires were detected while driving the vehicle “normally” and all systems operated as designed as long as we drove in that manner. But this car’s got a Hemi!
Radical! But not in a good way!
When traffic permitted, we tested how well the Hemi performed. Yes, tested. Hard. It was when the transmission was about to shift into second gear (and again later when it was ready to shift into third and when shifting into fourth) that there was what can only be described as a radical event. It was as if the engine’s controller suddenly forgot how to do so. There were backfires out of the exhaust. There were backfires under the hood. There was bucking and jerking. There was almost a loss of vehicle control every time we put the car to this “test.” It was violent. It was engine load-related we agreed, since it didn’t matter what gear we were in, what speed we were going, etc. I decided to record as much as I could with the scanner (wiTECH) but under such conditions, it’s difficult at best to capture events like these let alone hang onto the laptop! We made it back to the shop without a law enforcement escort.
The engine sounded “louder” than it should be, as if there was a modified air intake, each time we accelerated. Sure enough, it had been modified, but not like you’re thinking. There was no air filter installed, and the air filter box lid, to which the air snorkel attaches, was not clamped down tightly. There was no sign of where the air filter might be. Does this information make you think (like I did) that the spark plugs might not have been replaced by a professional? My visual observations revealed no more surprises.
It was because of the owners saying the misfire condition was more prominent in wet weather that I immediately suspected a secondary ignition insulation violation had occurred. In simpler terms, I thought a plug wire or boot was leaking. I have a mixture of salt water in a spray bottle that I prominently labeled “Ignition Insulation Test Fluid” that works very well. When sprayed on ignition components while the engine’s running, it reveals the leaking secondary components with ease! Unfortunately, in this case, the engine continued running as smoothly as the engineers had intended no matter how much I sprayed on it. I began to get perplexed. Wouldn’t you? I hosed down the mess I made on top of the engine and moved on.
A look in the trunk
Having a nagging feeling that I’d better begin my next diagnostic step with a Battery/Starter/Charging system test I grabbed my Pico, a battery load tester and a battery conductance tester. I opened the trunk to find an exposed battery compartment. Usually there’s a spare tire cover and a spare tire to move before you can even get to the battery! All the obstacles were missing. I also witnessed a lot of corrosion on both of the body grounds that are located closest to the battery. I imagined I was going to find excessive voltage drops on all kinds of power supply and ground circuits to modules (but I was still in “information gathering” mode).
| Located close to where the battery is mounted in the trunk are two of six main body grounds |
At Gary’s shop, we used every test we could to confirm our suspicions. On more than one occasion he had learned one test might give a “passing” result while another might not. I had one test fail, another was “borderline” and the third test indicated the battery should be recharged and re-tested. But Gary wasn’t too worried here. His intuition was — we were not addressing the customer’s primary complaint(s) despite finding something that wasn’t quite “right.” I had to agree with him. This information would be used at a later date though.
The battery tests also led me to perform voltage drop tests because the battery was located in the trunk (and we all know where the starter’s battery cable terminates). There was over two volts difference between the battery positive post and the starter’s threaded stud to which the positive battery cable is attached! Gary said “I’ll make note of it” and asked me to continue to diagnose the misfire complaint. I suspected that with so much corrosion noticed at so many locations, that it might have an influence in an ECU’s performance. I had to prove it to Gary though, grumbling about that under my breath! I’m the guy who likes to fix problems identified and then see if the customer’s complaints are resolved. Gary’s not from Missouri but he might as well should be with his insistence on “show me!”
What the ECUs are seeing
I then scanned the vehicle’s systems. On all vehicles, I prefer to perform a complete network DTC test before I do anything else. My reasons are many — which include the possibility that more than one module may point to the same failure, that maybe there’s a network fault which interrupts communication throughout the vehicle (which may be causing the customer complaint) and of course, I use that information as a baseline to help me throughout the whole diagnostic process. There are more reasons. Maybe there are some reasons you have that I didn’t mention?
Of the 11 codes found in the twenty-one modules reporting on the network, all were “Stored” (History) DTCs except one, a P0420 — Pending — Catalyst Efficiency (Bank 1). Because stored DTCs could have occurred as far back as when the vehicle was being assembled, we cannot grace them with much importance during our initial evaluation. If you happen to see DTCs like this vehicle had stored, a P0315 (No Crank Sensor Learned) and a P0339 (Crankshaft Position Sensor Intermittent) and then couple them with the customer’s complaints, then it might be easy to suspect the CKP (Crankshaft Position Sensor) was the culprit.
Gary found one at a dealership, and had it installed before I knew what happened! I would have preferred to have scoped it to prove it was faulty but Gary owns the shop and made the executive decision to “just try it” and see if the vehicle ran differently. He said the part was cheaper than the time he’d have had to pay me to scope it (again, his call). Unfortunately it didn’t change how the vehicle ran.
I performed almost every test I could including power supplies and ground circuit(s) voltage drop testing. There were two bi-directional tests which gave me errors when attempting to perform them. These failures led us to condemn the PCM (Powertrain Control Module) due to suspected failure of internal components. The theory was if the PCM couldn’t properly run these tests, it might be improperly calculating what’s needed under a heavy load. A “Chrysler Reman” was ordered from the dealer, installed and attempts were made to program it to the vehicle. After several failed attempts, pinpoint tests were (re) done yet resulted in no problems found. Eventually the module cooperated, it “let” me program it and perform all the set-up routines that were required. A test drive revealed the violent, radical way it had been performing was now not present. “Hooray” we cheered, until it just shut off for no reason!
We coasted to the side of the road. It restarted and without incident, we got back to the shop. It was then that Gary allowed his tech to clean the SIX major ground points and the starter terminal connections in hopes one or more of them may have caused the stalling. For several hours after, we let the car run in the service bay. It would still stall randomly, while nothing was being done to it, several times per hour. Could this symptom be what the owners described as “does sometimes cut out when stop?”
Frustration builds
I’m sure you can imagine the testing that took place in the days that followed. Yes, days. Running the same tests I’d run before. Nothing was proving faulty though. Finally, out of desperation, we chose to order (from the disbelieving dealership) another PCM. The new one programmed properly on the first attempt, was set-up in no time at all and it resolved every drivability complaint the owners had! It finally ran like a Hemi was meant to run.
Have you ever noticed, how we interpret what a customer describes, can also be interpreted in many different ways? It became obvious our owners Jeff and Katie were trying to help me diagnose their complaints by using terms they thought I’d understand. I however, use those same terms to describe other types of engine running conditions than what was being experienced. I gave them kudos for trying. The “sometimes cut out when stopped” complaint was separate from the “Drives rough — jumpy — all the time, worse when wet” complaint. Also, we can now assume the “Not running on all cylinders” complaint was derived from some other mechanic sharing his or her thoughts about how it drove. It was early in my diagnosis that Gary asked me to chat with the owners. That was a wise decision because there was a lot we didn’t know about the car, and a lot they didn’t know about it either. For instance, Jeff had no idea how long they’d driven the car without an air filter. Communication is a critical element in accurate diagnoses.
Gary’s astute business instincts — to stay focused on the customer complaints — could have almost driven me nuts! I routinely found one problem on the vehicle after another. However, rather than calling the customer with each problem that I discovered, he had me resolve their complaints first. Without annoying them, without generating suspicions of “selling” work and without seeming incompetent, in the end he made many more sales on the vehicle. He first addressed their needs then, after earning their respect (and building up their confidence in his shop’s capabilities) it was a lot easier to address their next-most pressing needs, like their battery, etc. Oh, and that loud “rubbing” noise heard while backing? That was due to incompatible fluid in the transfer case. Yes, he serviced that as well.
It is a reality we must live with. To confirm our suspicions of what is wrong with a vehicle we must perform certain tests, most times repeatedly, and look to see if the results are the same. These techniques just happen to be similar to the statement “doing the same things over and over expecting different results is the definition of insanity.” That’s just crazy, isn’t it?
P.S. — Both PCMs bought from the dealership arrived in boxes that had several labels on top of each other, had mispositioned labels on the PCM itself and looked as if the cases were sand blasted. I’d seen better looking units come from aftermarket suppliers, which evoke my question “From where did the dealership source these modules?”
