Can ANYONE tell me any reason why the computer would "go bad" in a 99 5.9 liter Durgango? Last year we had the computer replaced because it was "bad" and supposedly the mechanic said the cause was because of the distributor cap and rotor being bad (and possibly something in the ignition system too) but a year later the check engine light has been on and the same mechanic says now that it was the idle control valve and that the computer is bad AGAIN!!??? I KNOW I should not have to replace the computer again since he was the one who "diagnosed" the problem which apparently he didn't diagnose right. So I'm trying to find out the REAL reason why or what would cause the computer to go bad. I am planning on calling the dodge dealership and talk to a mechanic who can hopefully give me an HONEST answer but my faith in mechanics is just non-existent now. Thanks for your help and advice I feel hopeless right now and don't know what to do.

 

The causes are mainly electronically failures. Spikes of current or arcing of voltage will do it for sure. Humidity, excessive heat, workmanship, and some other unknown causes.

If the truck starts then the computer is good period!

The IAC valve (idle control valve) on these rigs have some problems. They are cheap and easy to replace. If the check engine light has came on or is on take it to Auto Zone and have them read the code. This is a free service they provide. Then come to us and we can tell you what to do in detail how to fix it.

You can always start a thread about anything you want to know or talk about a problem and we will help ya out. This is why we spend so much time here helping people out because we are sick of these people trying to pass things like this out.

 

THANK YOU SO MUCH Hydrashocker! The truck has been running almost perfectly except occasionally the idle is way too high and on the other end of the spectrum sometimes when I start the truck I have to give it some gas for a few mins or else it dies. The mechanic I am weary of just replaced that valve and the distributor cap and rotor yet the check engine light is still coming on with the same P0505 code. I am going to call a Dodge Dealership and talk to one of their mechanics to see what they say......or maybe thats just a waste of my time. Not sure what else to do cause I am really thinking this mechanic guy is not as knowledgable if he's telling me the computer is bad after just barely 1 year of being replaced and like you say if the truck starts/runs then its not bad. But thank you so much for your info, I am trying to become more informed about this situation so I can go and discuss this "misdiagnosis" with my mechanic, I refuse to pay for another computer if he didn't fix the original problem. Thanks again!

 

Also to add, the PCM is located in the engine bay! so it gets exposed to all the elements. Don't know why chrysler put the pcm in the engine bayis beyond me. I would get another mechanic to get a 2nd opinion on your problem.

As Hydra stated, most likely it would be some sort of electrical problem that would cause your pcm to burn out. Most common causes may be a bad wiring harness. Have it inspected. Make sure the connection sockets are in great shape and make sure there are no broken areas of the plastic cable cover that protects the wires. Exposed wires would lead to deterioration and cause problems with the pcm.

I had nothing but computer and charging problems on my 1985 Shelby charger. I had the pcm replaced 6 times in the 15 years I had it, along with new other sensors that keeps going out. Before I finally and painstakingly sold it (I wanted to keep it because it is a rare collectors item now) when I cannot keep up with the electrical issues anymore.

After selling off to a collector, he came back to me a couple months later telling me that all the electrical issues have been fixed. He had all the wiring harnesses completely replaced, properly grounded and protected. Car been running fine since. Wished I knew this much earlier, I would still have my car and driving it today!

 

Thanks for the info about the wiring harnesses......I'll make sure to mention that to this mechanic/joker...j/k. And see what the guys at the Dodge Dealer tell me. I LOVE THIS SITE!

 

OK well dealer Service guy says to bring to him for $140 diagnostic and that sounds like the other mechanic guy is just "throwing parts" at my truck! So.......what should I do? I feel I might as well bring it to him because the mechanics at the dealerships KNOW the vehicles because they are their vehicles! On the other hand I know dealers can pretty much rape you with their costs.......if anyone has any input I am grateful. Will see what the husband says.........should have taken mechanic classes instead of majoring in Child Development, lol

 

Wredheadgirl,

Let's start from the beginning again and hopefully we can provide you some insight to your problem.

1. Initially pcm went bad. Replaced pcm and I would assume you replaced ignition system (spark plugs, wires, cap, and rotor)
2. Year later, you have a check engine light and possibly another bad pcm and now bad Idle Control Valve.

First and foremost, if your PCM is indeed bad, it would be like Hydra say, it won't run. If your Durango is still drivable, the PCM should be okay. Can you tell us what is currently happening to your Durango with the check engine light? running rough? stalling, etc.....

Also, please find out what the code is that the check engine light represents:

Link to tell you how to obtain code: This is for a newer durango, but hope it still works for your 99 model. Anyone feel free to provide her the steps to pull the codes.
https://dodgeforum.com/m_698936/tm.htm

Link to definition of engine codes:
https://dodgeforum.com/m_614377/tm.htm

Once we have all the info you can give us, we will try to provide you with a correct path of action to resolve your problem.

 

Well the initial problem is as you stated

1.) (everything you said) PLUS the distributor cap and rotor were replaced because he said those being bad caused the PCM to be bad, however I now have to doubt that since I'm having the same problem just about.

2.) The check engine light has been on for a while (I admit that I should have brought it right back after the PCM was replaced, but I didn't) the code reads P0505 idle control system malfunction of some sort. I brought it to him to get that light off because I am due for a smog. He "diagnosed" the problem as being a bad idle control valve (or maybe the correct name is the IAC valve?) so he replaced that. That cost me $270 and when I went to leave the shop the check engine light was STILL ON! The other "symptoms" were that the truck occasionally idles very high and/or occasionally when I go to start the truck it just dies unless I give it some gas for a few minutes. The idle was still running high even after he replaced this valve. So he did some further diagnostic stuff and thats when he calls me to tell me that the PCM needs to be replaced, during the diagnostic stuff he also replaced the distributor cap and rotor AGAIN, and he tells me this time that the bad valve is what caused the PCM to go bad.

So I basically no longer trust that he really actually knows what is causing the PCM to go bad as he says. The truck was still running fine (except for the high idle) when I left it there yesterday so then the computer can't be bad. But the same engine code (P0505) comes back on after they clear it. I hope that clears things up! lol, its just been frustrating cause I'm really feeling like I'm getting dicked around now. Seriously thinking of taking it to the dealer tomorrow for a diagnostic that I can hopefully trust. Thanks for the links!!!

 

Beth,

I would take it to the dealership and pay the $140 to get a diagnostic checkto get a 2nd opinion to make sure the IAC was installed and running correctly. It may also be possible that the IAC may be bad straight out of the box.

If you did not have the error codes but still have idling issues, I would recommend you to replace the Throttle position sensor. The TPS are common problems on 1st gen durangos. $3x.xx part and easy do it yourselver. take couple minutes to replace.

I also just realize you have a 5.9. When the mechanic replaced your spark plugs, make sure they are not plantium plugs. 5.2/5.9 family engines hates plantium plugs. I recommend the oem brand Champion plugs. They now offer iridium tips which are rated good for 100k miles which is much better than plantiums and works great for the 5.2/5.9 family engines. You may also want to make sure the wires replace are the correct type. Hydra says oem were 8.5mm if I remember correctly.

If you takeyour durangoto the dealer, hopefully a reputable dealer, they can tell you if all that the previous mechanic replaced are correct oem compatible parts.

 

Beth:

Before you spend any more money at dealers or shops, get your battery load tested. Our Durangos are very sensitive to a failing battery. If it is more than 4 years old, or tests the least bit flakey, replace it.

Many a D owner has spent big bucks chasing idle and other issues only to find that their battery was on the way out.

If your battery does not meet this criteria, I would replace the TPS just for good measure. It is an easy DIY fix, and you have more than gotten your money out of the OEM unit.