I have a 95 wrangler 4.0 that runs like crap. Idles rough and has no power. Misses and back fires when under load. Check engine light shows TPS. Have replaced it 4 times. Tested the signal wire for voltage. I get 4.8v at idle and then it goes down as the throttle is opened. Opposite of what it should be doing. Took it to the dealer and they said the pcm is bad. My question is I’ve heard the three capacitors on the pcm are common areas for failure on the pcm. Do any of these capacitors provide power to the tps. Or is there any other replaceable components on the pcm that controls this. Pcm are hard to come by and repair services are nonexistent locally. I could ship it off states away but that takes too much time. If I can figure out another solution first I’ll do that as a last resort. Thanks for the help
PCM issue
- Thread starter Drossiter
- Start date
Usually the capacitors going bad gives no start symptoms, and no check engine light when you flip the key to run. Then if you leave the key in long enough, once the capacitors finally get enough juice to power the PCM, you finally get your check engine light, fuel pump primes, and it’s ready to start like normal. If you don’t have those issues, I’d say you probably don’t have bad capacitors, but that certainly doesn’t rule out a bad PCM.
What sucks is the pcm repair services on eBay are usually just soldering in new capacitors. They aren’t doing exploratory to find and fix anything and everything wrong with the PCM. Usually they only offer capacitor services and that’s it. Personally, I’d start trying to find another one. If you have a manual, it shouldn’t be too bad to find one as you can use any 91-93 4.0 auto or 91-95 4.0 manual pcm. They are getting more rare by the day but they are still out there.
As for the capacitors powering the TPS, I’m really not sure on that, but if they did power it, I would think you’d be having the no start issue like I mentioned previously.
What sucks is the pcm repair services on eBay are usually just soldering in new capacitors. They aren’t doing exploratory to find and fix anything and everything wrong with the PCM. Usually they only offer capacitor services and that’s it. Personally, I’d start trying to find another one. If you have a manual, it shouldn’t be too bad to find one as you can use any 91-93 4.0 auto or 91-95 4.0 manual pcm. They are getting more rare by the day but they are still out there.
As for the capacitors powering the TPS, I’m really not sure on that, but if they did power it, I would think you’d be having the no start issue like I mentioned previously.