Hi there folks. I’m Saul Reisman here at Saul’s AUTOTEK and today we’re going to talk about some common electrical problems in Denver vehicles.
Now, a lot of do it yourselfers or shady tree type mechanics might try and do the majority of their own repairs themselves and that’s fantastic. We’re here to help you and if you need any advice, feel free to give us a shout. We’ll answer any questions we can. However, there are a few things that require some serious technical expertise and may require a certified technician to go a little bit further. One of those fields that we often get asked to help out with is electrical diagnostics. Now electrical problems can be difficult to diagnose. Sometimes they can be found in a few minutes, sometimes they might take hours and hours to chase down some vehicles that we’ve seen have common core electrical problems. We’ve decided to put together a few videos about to educate you so that you can best be prepared.
Now between 1999 in 2004, Daimler Chrysler and Mercedes-Benz partnered together. When that happened, part of the agreement was that Mercedes-Benz wanted their ignition and computer system used in all Chrysler vehicles. They did this so they could use their Carl Bosch engineered electrical systems on oxygen sensors, mass air flow sensors, and several other drive-train components that did provide necessary upgrades compared to Chrysler’s original electrical systems. However, the mating in those two systems didn’t really work out very well and vehicles produced by Chrysler between 1999 and 2004 had been plagued with electrical problems. Let’s think about what models might be included by that. The Chrysler group between 1999 and 2004 included Jeep, so it could be a Wrangler, a Cherokee, a Grand Cherokee or a Liberty like this 2002 Jeep Liberty in front of me. Or Dodge, maybe a Durango or a Dakota could even be a sedan like a dart, maybe a pickup truck like a one-ton Dodge Ram 3500 or a Mercedes could be a C230, a Compressor, an ML 63 AMG.
It doesn’t matter. Could even just be a Chrysler Sebring or a Dodge Neon, anything produced under that Chrysler Mercedes partnership. Between 1999 and 2004 we’ve seen serious electrical issues with and we’ve seen revisionism problems with them from other shops doing previous repairs. One most common complaint that we have is that people are experiencing the symptoms they would typically associate with a bad alternator. If we know anything about vehicle electrical systems, we say that cars run on 12 volts. They don’t. Cars should be running with the engine operating between 14.1 and 14.9 volts. In the case of this vehicle, the alternator sits right up top, is driven off the belt drive and has this large positive output wire that goes directly to the battery. We’re easily able to measure the voltage going across it. We can also measure the voltage or amperage going across it as a reference to the ground or the chassis of the vehicle to determine the alternator’s output.
The vehicle came in and the owner was complaining that it didn’t start intermittently and acted as if there’s no electricity when that happened, but if they jumped at it would run. However, afterward, it would be dead again. Typical symptoms of what they had previously experienced of an alternator failure. When the vehicle came in, the alternator is charging at 13.2 volts. One might typically diagnose that and say, “you’re right, that’s a bad alternator.” However, in these vehicles, 9904 Chrysler Pentastar or Mercedes composite group vehicles, we have seen alternators charging low that are actually indicative of other electrical problems. Rather than just throw an alternator in it, ship it and say you’re good to go, we know that if something like that happens, it’s probably going to come back a couple of months or even a couple of weeks down the line, with a similar issue. Maybe even a failed alternator.
We’ve actually heard stories of some catching on fire after owners have replaced their own alternator in 1999 – 2004 Jeep Grand Cherokees with V8’s where they were charging low, replaced an alternator and there was actually a short in the system and created a fire from that new alternator generating such a high voltage in such high amperage comparatively. What we were able to diagnose with this vehicle was actually a problem with the PCM, the power control module, the computer that controls the engine itself. Now that computer has 12 volts applied to it and typically has five-volt driver circuits that go out from it to other operable on the engine, whether it’s sensors or small motors, anything on the engine. Electrical systems. Typically on that five-volt reference and a few components are on a 12-volt reference like your fuel bumper, the ignition coils. But, those are the only numbers we should typically see coming out of those computers. We noticed when we were going through our diagnostic process that the rear wiper wasn’t working appropriately. It seemed odd, but it didn’t seem to really correlate with what we were experiencing upfront. However, it was very indicative of the problem that we had. I’m going to take you over the computer now and show you exactly what we found.
Now, most shops won’t just assemble the computer. Your average auto repair shop is simply going to do some testing on the back of the circuit board. Maybe probe a few of the pegs and find out that there’s a short or something that doesn’t match what the manual says it should from a resistance perspective. We hear at Saul’s Autotek go a little bit further. We went ahead and disassembled it to figure out exactly what failed. And here’s where the problem is. On the actual circuit board, inside the computer of the three transistor packs, that would still be allowed to be mounted to it. One of them has actually gotten so hot, it is melted and is completely gone. It’s actually burned off the board. We can see additional charring where it used to mount, where the broken wires are, and it’s the original junction. And we can see black smoke coming off the corner of it.
Now, this is a pretty extreme failure and this is just to shorten that computer. This is a great example of a vehicle that could have experienced something really serious had it not had a proper diagnostic. We know that a lot of the do it yourselfers want to handle them on your own and we support you. But if it comes to an electrical diag, I think it might be best left to the professionals. In the case of this PCM failure, we were able to find a replacement PCM for a couple of hundred dollars and get this vehicle back on the road. This won’t be an expensive fix and it will be in and out on the same day as time. However, had this had an alternator replaced and increased the voltage and amperage going through this short circuit that had already smoked out and burned, this could potentially cause serious problems. This computer itself lies just below the driver’s knees or sorry, just above the driver’s knees in the dashboard of the vehicle.
So of all the places to have a fire happen, this would have meant the owner would have experienced smoke coming out of the dashboard directly in front of them, possibly affecting or inhibiting their ability to breathe as it would have been from burning plastic, which removes all of the oxygen from the air in the passenger compartment of vehicle. Additionally, this vehicle sucks in fresh air through the cowl panel, which is on the bottom of the windshield, which means it would have been sucking in smoky air as well. The owner may have had this catch on fire above their knees and the dashboard, and in the first couple of seconds that it was burning, they’d be inhaling those fumes, that burning plastic, maybe even having pieces of it melt out, out of that dash below them, under the legs before they even knew what was happening. If this happened at high speed or while you were cruising down the freeway, just in time it takes you to pull over is about how long it takes to start burning those things into a fire. And we’ve seen many of these be complete vehicle fires.
We care about your safety. We know you want to get the least expensive repair but get the best for spare possible. Take care of the do it yourself stuff on your own. When it comes to electrical repairs, come and see us.
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