Possible Pcm problems!
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Possible Pcm problems!
My trucks a 94 4.0 ranger 2wd. Been having problems with my truck running poorly! Put new o2 sensors in, maf sensors good. I pulled the codes and it came up with, 157, 158, and 543. _Low voltage to the maf sensor, high volatge to the maf sensor, and power to the pcm. _Since I know the maf sensors good, I think the pcm is the problem, but I'm not sure where the pcm is located. _My hanes manual didn't really have a good explaination of where it is. Has anybody else had this happen to their 4.0. My truck just hesitates to go, if it does move. Thanks for the help in advance!
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From: peoria, az
Sounds like you have a problem with getting power to your pcm. This may not be a PCM probleblem but, maybe a relay or a fusible link. I can do a little research on this and let you know what to look at if you have some time.
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Did both and they are still good, do you think that it may be the tps(throttle pressure sensor), my manual made it sound like that maybe the problem. My truck doesn't just go when I gas it, it will sometimes just barely budge and move, or it will go but off and on, then it will just take off like it's suppose to other times. I'm confued on what to do.
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From: peoria, az
I don't think this is a tps problem but, I could be wrong. Unplug your computer and make sure that you have power where it needs to be. I believe that pin #1 is the main place but there are more. I would have to look that up (in the morning). Check your grounds good too. If you don't have a good ground then you won't have good power. Also look at the connectors to be sure they are making a good connection.
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You know what I just remembered is that I unplugged the tps while the truck was running to see if it had any affect on the engine and it didn't do anything, i'm not sure if it should, but I thought that the tps told the pcm what fuel ratio to have the engine be sent.
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From: peoria, az
Well, kind of. The TPS tells the computer how far the butterfly(?) is open. It also looks at other things to determine how much fuel to add. The biggest one being the O2 sensor cuz after adding the fuel, it looks at this to see if it had the desired effect.
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From: peoria, az
I guess I should also say that if it doesn't "see" a reading from the TPS,it will substitute one.
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From: peoria, az
Yes, its possible. Ive found Fords to be pretty reliable with their codes though and I would have to chase the PCM power code first. Try and erase the codes and pull them again. If you get the PCM power code, I would follow that.
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From: Connecticut
A agree with stepman. You can reset your computer by taking the cable off of the negative battery terminal for about 10-15 minutes and then re-attach it (you should clean your battery terminals and cable ends while you are at it.)
Then drive around for a while and after that check to see if the same codes (or related codes) are present.
If so, then I would say you have a PCM problem and should check the #1 pin for power.
Also, I'm just wondering, how did you check the MAF to make sure it was good or not?
Then drive around for a while and after that check to see if the same codes (or related codes) are present.
If so, then I would say you have a PCM problem and should check the #1 pin for power.
Also, I'm just wondering, how did you check the MAF to make sure it was good or not?
