Is there a common place for bad ECM or PCM connections?

I looked at all three plugs on the PCM and one on ECM. Everything looks good. I guess next step is to pull back all the wire loom and start searching.

Battery cables are good and good grounds.

Got code for P1693 - Bad bus communication.
Having trouble with APPS, but just replaced that. No luck
Wait to Start and lift pump not acting right either.
Periodic issue with crank, but no start. Starts right away on a retry.

 

i have never heard of a common place of a bad connection.

i wouldn't concern yourself with code 1693.

if I'm not mistaking, the ECM turns on the lift pump, the PCM controls the cranking.

look under the ABS module/unit, some did not have a wire grounded from the factory and it took years for problems developed. it is a small wire with a eyelet on the end.

 

I'll check the ABS. Funny you mentioned that because I am also getting the ABS and Brake warning lights. They come on and go off at random times.

 

Found the ground wire under the ABS. It was hanging down on the inner fender.

Cleaned off the paint on the fender and grounded it.

Had issue with the APPS today, but verified it had correct output voltage. I'm leaning towards the ECM more now.

 

could also be the regular 'bad bus' deal which SEEMs to be a function of the connectors on the bus between the ECM and PCM. Seems to be some poor or fatigued solder joints in the gauge cluster, the connectors, and/or circuit boards. There is a thread on it in the non driveline forum which implies it could also be related to a bad pigtail on the alternator.... I have been fighting this with limited and intermittent success for several years so please let us know if you find a real fix

I will be checking for a disconnected ground this weekend too, just in case

 

I had a similar issue once. No dash function and odometer said no bus. Found water in the multiplugs behind and above the left front wheel. I cleaned and regreased the connections, and all was right in the world!!