Remand pcm?

Can't find my old thread. But I am %99 sure my pcm is bad. In my area it is tough to find used. Who has had the best luck with there remand PCM. Which manufacturer and where did you buy. Thanks

Twinzz said:

Can't find my old thread. But I am %99 sure my pcm is bad. In my area it is tough to find used. Who has had the best luck with there remand PCM. Which manufacturer and where did you buy. Thanks

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It isn't a 93, is it? I have one of those.

Sorry. It's an '01 belive it is not California emmisions

How do you know the PCM is bad?

Twinzz said:

Sorry. It's an '01 belive it is not California emmisions

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All 01's were CA emissions here in the US, I dont know about Canadian jeeps, they might be an export model.

Canadian Jeep Cherokees were built for the Canadian market and have Federal emissions. The only difference that I know of, Canada has a daytime driving light module. Headlights come on at reduced power when a vehicle is moving.

One reason I asked about the PCM diagnostics. (how you determined if the PCM is bad). Some people have been able to repair their PCMs with a little bit of solder.

Had iffy luck with anyone besides OEM computers. CARQUEST in particular sometimes takes a couple modules before I get a good one.

I found a used one for $50.00 with an updated firmware, works just fine. I keep it as a spare for while on the trail.

The main difference is a reman or new PCM will have the latest firmware with warranty. The company should re program the PCM with your odometer mileage reading and VIN.

The odometer mileage is also stored in the Instrument cluster.

A used one with the incorrect mileage reading won't effect the mileage from the instrument cluster.

PCMs are built to last, withstand heat, water, stress, etc. The main computers (there are three) are waterproofed, incased in a resin. It takes some effort to damage them, such as an circuit overload, overheating chips and other electronics, which isn't common because power circuits to and from the PCM are fused. Some have become damaged over time, because of pressure from the three main connectors, cause cracking and intermittent problems to one or two of the header pins solder joints feeding a five volt voltage regulator that feeds your sensors. (this is the type of repair some have been successful performing themselves)

There is no potting resin in my pcm. Red lowed the solder on as many joints as possible. Checked all the wiring for a chaffing found two little spots. Tested all sensors. Replaced the cps with a new jeep one. Cleaned all grounds. Thought the grounds were the problem at first the. It started every time and was running good. But then just quit again. The key lights up on the dash. It does have SKIM. If you heat the pcm with a heat hun it will start and run. Sometimes the key will illuminate but it still runs fine. Tried wiggling the PCM connectors and zaps traps. But did nothing. Did some PCM tests that another member has posted about. Which checked good. I tried a '00 PCM but it would not start at all. The '00 pcm has the part no.634 as. My factory one is a 801ad. I am at a loss. There is not a lot of support in my area. The thing has been off the road for three months with having so little time to work on it. I dont know what to do next. Was thinking mega squirt or something. Not sure if that would control the transmission though. I am trying to learn as much as I can. But a lot of the info out there is incomplete. And there doesn't seem to be as much out there about the DIS jeeps

I thought all PCMs were manufactured with a some sort of plastic resin around the main computer electronics. I haven't had mine apart .. from what I have read there is a voltage regulator stuck to the lid and mated through a header. The solder from some of the header pins sometimes crack from heat and/or stress from the PCM connectors.

I have always had good luck finding parts from wrecking yards, but usually their local, within 100 miles.

Here are some links for online searches for nationwide wrecking yard parts ... Some of the searches if you enter a zip code will find a part closest to your zip code.

Prices vary e.g. from ~$35.00 to ~$200.00 (some may include a warranty), most wrecking yards if a part doesn't work or fit you can exchanged them.

PCMs are fairly reliable and don't fail very often.

http://www.car-part.com/

http://www.salvageyard.net/

http://www.partshotlines.com/

http://www.junkyarddog.com/

PM'd a diagram of the PCM connections.

Its some type of mylar board, we have about every test we can with out much luck yet. the local dealer wants $840 plus the extra programming. I will tinker with it a while yet. maybe it is still a sensor acting up or somthing. its cold hear now, and it will only start when the PCM is heated. Baffling

Can you give me the part number off of your current PCM and I'll look in my database and see what cross references with it, I might have something here I can ship up to you.

P/N 56041 801AD. It's a '01 with the two pre-cats and 4 02's. It does have SKIM. But I would like to get rid of that option.

Twinzz said:

P/N 56041 801AD. It's a '01 with the two pre-cats and 4 02's. It does have SKIM. But I would like to get rid of that option.

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Sorry for the late reply, I looked up the part number and its an 01 automatic "50" state legal ecu. IE California emissions ecu. They also have lots of updates posted for it and the current most updated part number is P/N 56041801AG. since an 01 ecu is a pretty rare bird I looked through my collection of ecus and I don't seem to anything that will work for you.

I may be on to something. What I thought was the PCM is not. I tried another from the same make and model. I tried changing the ASD relay and cooling fan relay before with out any results. Recently now with the cool wheather. The jeep is acting differant and is harder to start. For the sake of it I switched the ASD relay and the cooling fan relay. It started with no throttle assistance. Then some problems popped up 50% percent of the time. The cooling fan comes on when the key is turned to the on position. Then it will not start. Sometimes the ASD will keep clicking. If you pull the cooling fan relay it will start and run. The check engine light comes on but I have not pulled the code yet. The only one it would pull before was 1694. That may still be an issue. The transmission shifts erratically. Looking for some ideas why it will start with the cooling fan relay removed. Thanks

is 1694 the bus communication error?

if so suspect a 5v sensor.
tps/map/vss all of the engine management basically. unplug one at a time to troubleshoot.