May have found my first bad PCM

[The_Jeff]

Just got this little project. year 2000 Chrysler Town & Country, 3.8, FWD.

have read about the flaky VSS, fusebox, PCM, BCM, and gauge clusters. Seems resoldering fixes lots.

Symptoms:

No speedo. Speedo self calibration (holding trip reset) makes needle move with the others. No cruise. Trans shifts thru all the gears, but you have to let off the gas for 1-2. Other gauges work.

CEL on. Two different generic scan tools won't connect, but do power up. CEL returns after a battery reset without driving.

Battery light is sometimes on. When on, a low 12 volts. When off, 14.x.

The pins are still shiny, even though there's a dark spot in the connector. I can't resolder this computer as it's full of brown goo.

 

[spackard]

It *might* be fixed by leaning the pins a little off-center so they make more contact with the mating connector. I've seen this tip in a Honda Tech Tips bulletin. But, exercise very good control over the pins so you don't slam them over.

It looks like poor contact caused local heating.

 

[The_Jeff]

Well, there's a problem. Might not be everything, but it's something.

I got out my super precise surgical computer tool (4" angle grinder with cutoff wheel) and got into the base of the computer case where the pins would solder in.

Concerned about metal dust, I was pleased to find another layer of brown sticky goo. Picking it out picked out the aluminum shards.

Scraping the goo with a screwdriver was tedious, so I broke out the wire brush on my drill.

This worked GREAT.

Until I rubbed off a copper trace near the edge. Note... keep it to the pins area.

Anyway I discovered a nice burn... of the sort I'm not sure, if I layed some solder, if it would go to the right place.

 

[GMBoy]

Yep, sounds like replacement time. It is rare for PCM's to go bad in today's cars but, as you found out, not impossible.

 

[mechtech2]

Ford's computers are reliable rocks.
Chrysler electronics don't compare.

 

[bdcardinal]

Originally Posted By: mechtech2
Ford's computers are reliable rocks.
Chrysler electronics don't compare.


+1 that majority of the bad PCMs we get are from people using those handheld tuners or from another component shorting out and taking out the driver in the PCM. You also get the ones that go bad when people play with wiring to add electrical components, see a nice juicy 12v line, tap and and then short it and burn the PCM.