New Computer

[Jsinclair92]

Hey guys,

Over the past few months I've had a lot of trouble with my truck. After taking it to two mechanics, and myself throwing tons of parts at it... we decided it needed a new computer. I have a new computer but I wanted to find out what caused the old computer to malfunction and fix that problem so the new one doesn't mess up too. I don't really know all that much about computers as I've never messed with them before. What could cause it to mess up, what tests could I do to find out?

Thanks,

Jordan

 

[HolyRamBatman]

Really hard to tell. Could have been a number of things.

Bad grounds, shorted wires, battery arcing, just it's time.

Have you had the old computer tested?

 

[dodge dude94]

A lot of times the PCM just goes out. Sometimes it's user error like ^Billy up there said, but from what I've seen, it's just random.

 

[Jsinclair92]

Really hard to tell. Could have been a number of things.

Bad grounds, shorted wires, battery arcing, just it's time.

Have you had the old computer tested?

No it hasn't been tested. It was throwing this code, though: P0601 Cruise. I'm about to put the new one on now, and I'm thinking about just changing the ground wire from the computer.. it cant be that hard right?

 

[Jsinclair92]

So I just put the new computer on the truck, and immediately I noticed it had excellent throttle response and more power. Well I went down the road to get some antifreeze, and then took it out on the highway to get it up to higher speeds to break in the PCM. Well, I noticed that it seemed to not be shifting gears, at all. I got it up to 55mph at nearly 4,000 RPMs and finally gave up on it ever shifting. I had autozone run diagnostics on it and it was throwing an O2 sensor code (P0031). But that wouldn't cause it not to shift properly. Any ideas?

 

[NYCruiser]

If I'm not mistaken, the older trucks tranny's aren't controlled by the engine's computer. That's why you couldn't get tranny tunes on the older trucks. The tranny problem may be elsewhere.

 

[Jsinclair92]

It is kind of coincidental that the truck wouldn't shift within minutes after I put the new PCM on though

 

[NYCruiser]

Double check you wiring. Make sure you didn't knock anything loose like a ground or blow a fuse


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[Jsinclair92]

Oh and I also should have mentioned that I heard a new ticking noise coming from one side of the engine block after I put the new PCM on. Any ideas as to what that could be, and if maybe its the cause of the problem?

I'm starting to second guess if putting the new PCM on was worth it, I think I'd rather have the old one that was faulty, all it ever did was cause the engine to die haha.

I'm about to go out and check all the wires now

 

[Jsinclair92]

I disconnected the negative battery terminal and checked all the wires and fuses, and tightened up the ground wire of the PCM. Of course the check engine light was off since I reset the PCM, but once I got it up to 55mph again (and still in first gear) the check engine light came back on, throwing the codes P0031 and P0037, both O2 sensor related.

 

[NYCruiser]

was it shifting now?

 

[Jsinclair92]

No it wont shift out of first gear. I am going to replace the O2 sensor and its fuse, and the fuse to the PCM, but I am really doubting this will help the shifting problem. I am totally confused on this one, since you said the PCM doesn't control the transmission. Could it be something engine related (or something the PCM controls) that could keep it from shifting gears?

 

[LaurenMagnum360]

dont some trucks come with either 1 front o2 sensor, and some come with 2 front o2 sensors?

I know chevy did this in the 90's, not sure if dodge did something similar. If so, you could have a computer for a model with a different number of o2 sensors, and it's not seeing the one it is looking for

 

[Jsinclair92]

dont some trucks come with either 1 front o2 sensor, and some come with 2 front o2 sensors?

I know chevy did this in the 90's, not sure if dodge did something similar. If so, you could have a computer for a model with a different number of o2 sensors, and it's not seeing the one it is looking for

Yeah you're right about some coming with 2 o2 sensors. I think some have a sensor in the header and one further downstream, but don't hold me to that. Though I don't think any of the 2001 dodge's have two, as far as I know. THE PCM I bought came from AutoZone, and they assured me it was the one for my truck.

Also, before the old PCM I had died it was throwing an o2 sensor code. So the o2 sensor problem is actually older than my PCM problem, I guess I just put the o2 on the backburner because the truck was having bigger problems. Now, it wont even shift gears.

 

[LaurenMagnum360]

i would throw the old ecu back in and see if that fixes the problem. You may need to have the ecu flashed at the dealer also for your trans.

 

[NYCruiser]

There should definitely be 2 O2 sensors. One on each side of the cat.

 

[Jsinclair92]

I put the old computer back on and the truck ran just fine (other than the dying on low idle problem, which is related to the computer being bad). It shifted okay. So apparently some problem with the new computer was causing the truck not to want to shift. I'm not real sure what to do from here. I'm gong to call the manufacturer tomorrow and see what they have to say about it, it's likely I'll have to take it to dodge as you said.

 

[Jsinclair92]

I'm also replacing the fan clutch (it's dragging and whines pretty badly), changing the water pump and radiator cap because they're leaking, new t-stat, change and burp the coolant system, and put new o2 sensor and fuses on. All of this has cost me a few bucks so I hope it fixes the laundry list of problems it's having.