hello again ...
when changing the battery in my truck after leaving it idle for 2 weeks.
My cousin lent me a battery and he got confused when connecting it and it made sparks when he briefly connected the terminal (it was removed immediately)

Then when I connected it correctly it didn't turn on.

here what I tried:
1. test all the fuses of the 2 boxes (I couldn't remove the 140amp one, I tested it there and it gave continuity)

2. The Instrument Cluster turns on all its lights and turns them off without any check (the voltmeter goes up a little and stays at 8-9V)

3.the starter motor works (it seems that there is no spark, I don't check it)

4. The most worrying thing, the fuel pump does not sound or activate, so I checked the relay and there is no ground (it works by bypassing the relay), as I investigated, that ground is provided directly by the computer/pcm/ecu.

Here is my question: can I check the PCM grounds? Any other fuse box that I don't know about? Any broken connections?

the fried pcm?

It should be noted that I tested the relay by connecting it to the horn and it works, in addition to all the lights inside and outside, the radio and windows, windshield wipers

dodge ram 2500 1998 4x4 magnun 5.9 automatic single cab short box

 

PCM isn't controlling the relay..... As the relay is good, that doesn't bode well for the PCM.... May have smoked it hooking the battery up backwards. Do you have a scanner? See if it will talk to the PCM.....

 

There have been others that did the same thing, Usually if it was hooked up backwards it fried the pcm.

 

you know where the ground comes from

 

So it is most likely that the PCM is damaged.

It can be changed for another PCM directly or it has to be programmed for the pickup.

and it has to have the same characteristics as my truck, I mean the PCM has to come from a 4x4 truck from 1998 or they have some flexibility.
or are they ones that have to have a specific serial number for it to work?

 

98 will need to have the VIN flashed. I like to get them from a local source, that way, if there is a problem, I can talk to a live human being, in person, not some voice on the phone.