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Looks Like a Dead PCM

D

dktool

NAXJA Forum User
Location
Covina
My '98 Fed model suddenly developed a no fuel pump relay power on -time out function, there for no ticky no runny.

I swapped relays, checked fuses etc.
If I wire a switched hot lead to the O.N. output side of the relay base, the pump turns on and everything if fine until I turn the McGyvler switch off, then the pressure drops and it dies.

The Chrysler p/n on my PCM is: P56041 with another number in bold print: 534AF

Anyone have a quick good local source for the PCM ?
Does it sound like my diagnosis is good ?

Thanks
 
dktool said:
My '98 Fed model suddenly developed a no fuel pump relay power on -time out function, there for no ticky no runny.

I swapped relays, checked fuses etc.
If I wire a switched hot lead to the O.N. output side of the relay base, the pump turns on and everything if fine until I turn the McGyvler switch off, then the pressure drops and it dies.

The Chrysler p/n on my PCM is: P56041 with another number in bold print: 534AF

Anyone have a quick good local source for the PCM ?
Does it sound like my diagnosis is good ?

Thanks
Click to expand...

There are a few things that could cause the fuel pump not to energize, if you want I have a DRB3 and we can test the fuel pump output on the ecu and chase it down through the PDC.
 
That would be a very kind offer if we could arrange a meeting time.
My schedule lately is all over the map.

What works for you ?

Also, please see my edit in the op regarding the number, any knowledge of that ?
 
That's not the kind of challenge I would impose on anyone unless I was selling something !

What do you think about that second series of numbers ?

What time do you get home from work ? I could drive it out there with the Micky-Switch.
 
dktool said:
That's not the kind of challenge I would impose on anyone unless I was selling something !

What do you think about that second series of numbers ?

What time do you get home from work ? I could drive it out there with the Micky-Switch.
Click to expand...

If it was a bad CPS, it wouldn't run when you jumped the fuel pump.

as for the number on the ecu, the 3 digits are the calibration id and the last two letters are the calibration revision. If I look in my files I might have the configuration you are running.
 
Do you get a check engine light when you turn the key on, before you try to start it?

Thats how I diagnosed Phils computer to be toast - should show the CEL with key on as a self check.
 
Follow up:

I unplugged C3 and checked continuity from (socket) 19 to (socket) 6 at the relay base.

If I really wanted to be extra anal I could snake a lead out of the C3 pin 19 and verify it is dead (no -) when running, or I could ground the C3 19 socket with the key turned on and the relay would make, but those extra steps are unnecessary.

It is currently running 100% normal with the temp-ground switch set up.
I am shopping for a replacement PCM so if anyone has a good lead on one, let me know.

P/N P56041 534AF

UPDATE: I purchased a PCM off Ebay with the EXACT P/N and program code. Didn't want to take any chances with the program code unless it would double my mpg, it would be great to get 22 mpg !
 
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