There was absolutely nothing wrong with the charging system when I took the truck in.

Tiny
SHUNT0202
  • MEMBER
  • 2001 DODGE RAM
  • 131,000 MILES
What would cause a Voltage Regulator in the PCM to just suddenly go out without any warning in a 2001 dodge Ram 1500 4x4 5.9L? I took my Dodge in for a tune up. After they replaced valve cover gaskets, did the tune up, replaced thermostat gasket, all without disconnecting a battery cable from the terminal, and then kept the truck for 3 days, didn't bother telling me until I basically demanded to pick the truck up, coincidentally, my voltage regulator just quit, and I had to get a new PCM. They say coincidence and I beg to differ. I had NEVER had any issues with my charging system before I took it in there, and when they called me to tell me the work they were doing, there was no mention of anything being wrong with it at that time. Rather fishy to me. They did something to cause this to happen, and I want to prove it.
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Friday, December 2nd, 2011 AT 2:03 AM

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Tiny
SATURNTECH9
  • EXPERT
Its going to be hard to prove though it does sound fishy though if there never was a problem with the charging system.
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Friday, December 2nd, 2011 AT 2:23 AM
Tiny
CARADIODOC
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Hi guys. There wouldn't be any need to disconnect the battery for the services listed. In fact, you can run into a lot of totally unrelated problems on newer vehicles from computers locking up when the battery is disconnected, so most of us go to great lengths to avoid doing so. Also, I can't think of anything I could do to intentionally or accidentally damage the voltage regulator circuit. That is one extremely trouble-free system. I even had a few Engine Computers on Dodges that I took apart to create defects that I could switch in and out for my students to practice troubleshooting skills on regulator circuits. Those circuits wouldn't die.

Here's what IS fairly common. The Nippendenso alternators develop worn brushes that cause an intermittent charging system. You have no idea when that problem is going to first show up and it could very easily be in the repair shop. Mine acted up on my '88 Grand Caravan about four weeks ago at 230,000 miles.

The brush assembly costs less than nine bucks and is real easy to replace after just removing the rear cover. The job can even be done on many cars without removing the alternator from the engine. You can verify this problem by measuring the voltages on the two small wires on the back but they have to be taken with the engine running. One will read full battery voltage. The other one must read less but not zero volts. When the brushes are worn, that second wire will have zero volts. If the voltage regulator circuit is open, both wires will have exactly the same voltage. It would be more likely to find a corroded terminal in a connector than a bad computer.

If I'm right, it's real possible your charging system will work fine when you pick up the truck, then cut out intermittently, possibly days or weeks from now. A lot of mechanics, especially those who don't have a good understanding of electronics, jump on the computer right away because they're used to it being the solution so often.

If I'm wrong, the computer could indeed be defective, but it's the very last thing I would suspect. Given that it occurred while other services were being performed, particularly valve cover gaskets, I'd suspect a cut wire or stretched pin in a connector. Regardless, I doubt the computer was damaged by the mechanic. I know that's not what you want to hear, but you have no way of knowing when the failure is going to occur. You wouldn't blame the gas station attendant if the charging problem showed up after you filled with gas. You wouldn't blame the toll booth operator if the problem occurred after stopping to toss 'em some coins. As a former mechanic, I've run into things like this that had nothing to do with what I was working on, yet I was blamed for everything from burned out light bulbs to rattling shock absorbers.

Now, that's not to say your mechanic DIDN'T accidentally cause a problem but if he did, he should repair it at no cost to you. A cut wire, which I think is the most likely cause, would definitely get fixed for free. Worn brushes can't be foreseen but some shops would replace them at no charge to you to maintain good will. Most mechanics would replace the entire alternator instead of repairing it due to less time and to insure a quality repair, but they might go the brush assembly route to keep their cost down, and overlook the added labor time. I could understand a shop asking you to pay for a computer because they are also going to be of the opinion it was just bad timing, and nothing they caused.

A less than reputable shop MIGHT try to make you pay for a computer so they'd have some money coming in to cover their time spent tracking down and correcting the real problem that they caused. That would be highly unethical but every industry has their bad apples. Even a mechanic could lie to his boss to cover his behind so don't be too quick to fault the entire shop. I think I would try to ask them to reinstall your old computer after all the repairs are completed. If the charging system still works, they either caused and repaired some other problem or the brushes could be intermittent and the system started working right after they replaced the computer. That would just be dumb luck. In either case, I would ask them to leave the old computer installed and tell them you'll take your chances with a possible intermittent problem. That will give them an out without having to admit fault. Here again, if I'm wrong, PROVING they caused a problem isn't going to do any good but giving them a way to back out gracefully might save you that cost. If an intermittent charging problem pops up in the future, we'll help you diagnose it at that time.

To boil it all down, the possibilities range from someone could have caused a computer problem to there is still an intermittent problem that's going to act up again. If I were asked to guess, I'd be leaning toward there's still an intermittent problem but if it really needed a new computer, I don't think they caused the problem.
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Friday, December 2nd, 2011 AT 4:15 AM
Tiny
SHUNT0202
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The Dodge is a 2001 model. In the repair manual when replacing a thermostat gasket, it says to disconnect battery cable from terminal, and I can see why, being so close to the alternator. The shop that did the initial work replaced the alternator for free, so that to me, is an admission of guilt. That same shop is the one who sent me to the Dodge Dealership to have the PCM replaced after the alternator didn't change a thing. The truck had NO previous issues in the charging system. Nothing intermittent, NOTHING EVER. Of course the charging system is working fine now that a new PCM has been installed. Therefore, I am not buying that the shop didn't do something during the course of their work. They couldn't even put the same oil cap (which, incidently was brand new) back on the valve cover that came in on the truck. They threw some old thing on there they picked up out of their shop. To me, that is a sign of some sloppy work. That is not ok with me. And why do you suppose they had to keep the truck for 3 days to do a 1 day job? Because they messed something up and they knew it? Also, if they were replacing valve cover gaskets, the wiring that runs from the PCM to the alternator runs right up along side the valve cover area. A lot of room for error. Question: Does the wiring system from the alternator to the PCM have a fused circuit? I appreciate any and all input.
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Sunday, December 4th, 2011 AT 10:14 PM
Tiny
CARADIODOC
  • EXPERT
Can't argue about the proximity of the wiring to the thermostat housing, but I've never disconnected the battery to do that job just because we run into so much trouble by doing so on many newer vehicles. We joke in the shop too about the service manual listing that step. "Disconnect the battery before replacing the wiper blades". "Disconnect the battery before emptying the ash tray". I know that sounds sarcastic but the reason for doing that is liability. If anything happens, the manufacturer can say "you didn't follow procedure". A common sense approach is to unbolt the alternator fuse in the under-hood fuse box. That will remove the short potential at the alternator's output terminal without risking locking up any computers. I removed the alternator from my minivan a few weeks ago to replace the brush assembly, and I didn't disconnect the battery. Obviously I'm not suggesting anyone else be that lazy but in my case I avoided the possibility of cracking the decrepit lead terminal on a 23-year-old vehicle.

To add to the insult, I rarely disconnect the battery when removing an air bag, and I'll guarantee you every service manual has big bold letters stating that requirement. Again, it's for liability. We've had so many warnings but now that I understand how the systems work and all of the safeguards that are built in, I know why we don't read about mechanics being injured from accidentally deploying an air bag. The few that do deploy accidentally are usually the result of careless handling and they are already disconnected from the car's electrical system, so what good did that "disconnect the battery" step do? Here again, for the other people reading this, please do as I say, not as I do, and disconnect the battery. I'm only pointing out that this step is listed for a reason so it should be performed.

Many mechanics do not have a good understanding of electronics because they can't see or touch it. Those people are naturally going to replace the alternator as a first attempt because everyone knows the voltage regulator circuit is extremely trouble-free. I can't think of anything I could do to intentionally damage one other than hitting it with 120 volts house current. You may indeed have found an inexperienced / sloppy / incompetent / distracted / careless mechanic but you have to at least keep an open mind that it's possible he didn't cause the charging problem. Problems occur all the time. It's a matter of where the truck is when that happens. I've been blamed for dead horns that didn't work so no one would open the shop door for me. How the owner could think I caused the problem by pressing the horn button is beyond me. A woman blamed me for a noisy wheel bearing, ... Three weeks after I replaced her wiper motor. A lot of mechanics have been blamed for multiple problems on anti-lock brake systems because some computers can only set one diagnostic fault code at a time. A second or third problem won't be discovered until the first one is repaired. Really hard to give an accurate estimate on those cars.

As for your oil cap, that is sloppy work but it's real easy to understand, especially if two or more people were involved in the repairs. Who would expect to find a new oil cap on a ten-year-old truck unless they took it off them self? If I were asked to help on a job already in progress, I would likely assume a new cap was for some other vehicle, especially if the guy next to me was working on a newer one. Most mechanics leave the oil cap on the engine when it's removed but some put them on their work bench so they'll see it if they forget to put it back on. Your cap likely ended up on the bench with the valve cover that was being cleaned up. Again, a wrong oil cap is not a sign of a professional, but it's hardly worth holding the entire shop in contempt.

There's always two sides to every story. I spent a lot of time in the classroom preparing my students in ways to prevent things like this from happening. Even the best-intentioned mechanics make mistakes but isn't it funny we hold them to a much higher standard than doctors? Doctors just bury their mistakes, or we run from one to the next until we find a diagnosis we like. Boy, let a mechanic do something wrong to our transportation and they don't deserve an ounce of forgiveness, or even the benefit of the doubt. Of course you are going to hold your mechanic responsible for everything that happens to your truck from now on. It's human nature to want to blame someone else.

Working on cars and tvs for so long, I've seen a lot of things break down right in front of me so now whenever I get less than satisfactory service from anyone, my first thought is how could this have happened without it being the fault of that waitress, cashier, carpenter, mechanic, etc. I don't blame the person until every other possibility has been examined, and then I know it doesn't do any good to get angry. No one is going to go out of their way to help someone who is yelling, won't listen to reason, or is just looking for someone to blame.

I can't fault you for being unhappy, but from the tone of your posts, it sounds like you won't even entertain the notion that the mechanic did not cause the charging problem. It sounds like you aren't sure and you want us to verify that he is to blame. I would certainly suspect he DID do something since he was in that area, but given the really low failure rate of older Chrysler Engine Computers, especially the voltage regulator circuitry, I'd be looking in other parts of the circuit first. There could have even been a little surface corrosion on a connector pin at the computer or in the plug in the middle of the wiring harness. The simple scratching action of disconnecting the plug and reconnecting it will scrape a clean spot that makes a good connection again, ... For a little while. We saw that all the time with tvs. Pull out a plug-in module to visually inspect it, find nothing wrong, plug it back in and the tv works fine! That was so common that I built similar defects into the cars my students used for practicing their troubleshooting skills. Who is to say there wasn't a little corrosion on your computer plug, and by wiggling it during the valve cover service, it aggravated it enough to cause a bad connection? That would APPEAR to be solved by installing a new computer, but the real proof would be to stick the old computer back in and see if the problem was still there. You haven't even considered that possibility but in my electronics experience, that is a more likely scenario than a defective computer. As further proof, we used to send tv modules in to the manufacturer for repair and they would sometimes come back labeled "no problem found". A different module got the tv working, and that old module worked fine in a different tv. That didn't happen all the time but it happened enough that it wasn't worth discussing in the shop.

You said you want to prove your mechanic damaged something. To do that you're going to have to figure out exactly what happened, otherwise "coincidence" is an unlikely but very real possibility. MY alternator was working fine up to the point I parked in my friend's driveway. It was dead as soon as I restarted the engine and left an hour later. Can I blame the worn brushes on him not fixing my laptop properly?

I physically took Engine Computers apart on a '95 Intrepid, '97 Dakota, and three Shadows to purposely cut some internal connection to create a voltage regulator defect that could be switched in and out for my kids to diagnose. I've seen them accidentally short that voltage regulator wire to ground and apply 12 volts directly. THAT'S how I know you can't kill those circuits. That probably doesn't make you feel any better, but it's why I'm not 100 percent convinced your mechanic caused the problem. The timing is suspicious but you have to at least leave open the possibility of an unfortunate coincidence. You might be right, but if you are going to insist he caused the damage, I'm going to insist, "not necessarily".
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Monday, December 5th, 2011 AT 12:34 AM

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