Engine/Transmission (1998.5 - 2002) PCM Price

[DLBurns]

If the price is right from the dealer I would prefer to just get a new one from them.

Still haven't figured this problem out??? Sure hope I don't fry someone elses PCM trying to figure out why mine is acting up!

 

[DLBurns]

To make it as simple as possible. The ECM deals basically only with the engine and it's sensors. All the rest it managed by the PCM. Then there is a data link between the ECM and PCM where they exchange informations. OK?



The transmission, AC, CC, Charge field for the alternator, the dash just to mention a few that come to mind are all directly powered and controlled by the PCM.



That's why I say it's confusing that also the APPS is off since it's a ECM only sensor. Now you say that you were monitoring the APPS THROUGH the PCM. That makes sense! Bingo, all the problems you have are now directly related to the PCM. See what I mean?



Anyway, before you try to buy a new PCM, open it. Maybe it's something really simple like the one in that other thread. Sorry I don't have any schematics about the internals of the PCM. They simply do not exist...

I've never seen this problem ( AC clutch ) before so I don't know where the "AC clutch transistor" is located. Off my mind... I think that almost all power transistors are located in the centre of the PCM.



Marco

Marco,

Here is the latest on my ongoing saga... we cleared all of the codes again and disconnected both the High pressure & Low pressure AC cutout switches and pulled the relay for the AC clutch in the PDC. We then started putting things back together, reinstalled the AC clutch relay, no codes or CEL... reconnected the low pressure switch, no codes or CEL... reconnected the high pressure switch and the minute the compressor cycled it through the code and CEL???

We though ah ha! it's either the low or high pressure switch. Bought new ones and installed them yesterday, same problem!!

The AC compressor is cycling on and off every 7 seconds, we checked Cliffmans and his didn't cycle off the entire time we watched it.

I pulled the PCM today and opened it up... everything looks OK to me, no burned traces like the other PCM in the link you directed me to.

Here is a photo of the PCM

Have any more ideas as to what to check next, I am seriously considering driving this thing into the ocean!!

 

[Marco]

Can you send me a HIGH resolution pic of the PCM?



Marco

 

[DLBurns]

On the way to you now, pics aren't that good though. I have already sealed it back up and put it back on the truck



Dave

 

[DLBurns]

We swapped out my PCM with Brads last night and when I turned the AC/Heater selector to AC it thru the code the minute the AC clutch cycled!!

At least I know it's not my PCM!!

Gonna check the switch and the voltages to the AC clutch as you suggested Marco. If that comes up OK, I may be tracing wires until the turn of the next century

 

[Marco]

Pin 1 in C3... . And have you taken out the AC clutch relay in the PDC and see what happens?



Marco

 

[BPINE]

Pin 1 in C3... . And have you taken out the AC clutch relay in the PDC and see what happens?



Marco

Yes we did Marco and it didn't matter either way. With the relay in we got no CEL but as soon as we pluged in the High pressure switch the CEL came on.

 

[DLBurns]

Marco,

We checked out pin #1 on C3 and found it to have 13. 5 - 14. 00 volts, when we switched on the AC via the selector switch the minute the clutch engaged it thru the code again and the volts dropped to 0. 11. The returned to 13. 5 - 14. 00 as soon as the clutch disengages. The clutch engages avery 5-7 seconds with the engine cold. I checked the temp at the vents with AC on Max recirculate it was about 41°!!

NOt sue I know where to go from here??

I sent you an email regarding this... as always any ideas are sure appreciated

Dave