Hi, I was wondering how to check out the pcm? I've a problem that has us stumped, and before replacing the whole fuel pump module it would be nice to check out the pcm to make sure it isn't the whole problem. I posted the question below earlier, and her it is to give you some idea as to where we are at. The jeep starts and runs now after sitting 3 mnths but the Snap-on Modis code PO463 keeps coming up but there hasn't been any problem with the fuel gauge. I'm guessing that the snap-on code is the equivalent of the hex code 96.
I've a 96 cherokee classic 4.0 L that was occasionally spitting, and sputtering on the way to work one day, and it wouldn't start after work. There was no power to the coil. Found a fuse in the PDC that was blown, #6 slot, 30 amp big fuse. Replaced it, and it spit, and sputtered a little on the way home. Made it home, shut it down, and it wouldn't start, it had blown the fuse again, and again. Diagnostic Trouble code #42 came up after cycling the key switch 4 times. Here is what is listed for MIL code #42.
Hex code 65/ Fuel Pump Relay Control Circuit/ An open or shorted condition detected in the fuel pump relay control circuit. or
Hex code 0A/ Auto Shutdown Relay Control Circuit/ An open or shorted condition detected in the auto shutdown relay circuit. or
Hex code 2C/ No ASD Relay Output Voltage at PCM/ An open condition detected in the ASD relay output circuit. or
Hex code 95/ Fuel Level Sending Unit Volts Too Low/ Circuit shorted to ground between PCM and fuel gauge sending unit. or
Hex code 96/ Fuel Level Sending Unit Volts Too High/ Open circuit between PCM and fuel gauge sending unit. or
Hex code 97/ Fuel Level Unit No Change Over Miles/ Sending unit reads too long.
The #6 slot 30 amp big fuse in the PDC is for the Power train control module, Transmission control module, & the Fuel pump relay.
The Cherokee has 246 thousand miles on it same with the fuel pump, and I was thinking maybe something in the fuel pump module.