Scanner / ECM communication failure

[matuva]

Good day all,

yesterday, I tried to reprogram a set of remote keyless controlers via the OBD-2 port, and the truck didn't respond.

I hooked my laptop to the port, and found that the scanner couldn't communicate with the ECM.

I have met this problem of communication with few trucks. Sometimes it was just because a fuse was blown, but sometimes, all fuses are OK and I still can't communicate with the ECM.

This is not easy for diagnosing :rolleyes5:

Does it ring a bell to one of you guys?

 

[NVW]

Al, I had a no connect problem with the cable that came with carcode. It is a two piece cable, if yours is like that maybe there is a poor connection between the cables. One of my cables was NFG so a new one was sent out.

 

[matuva]

Leo, I tried the scanner another truck, and it did connect with no problem.

I already had a problem like that, and it was the cigarette lighter which was blown. This fuse was certainly powering part of ECM circuit. But this time, the fuse is fine...

 

[WarWagon]

Check the grounds. If the ECM has low voltage or a bad ground it WILL NOT enter diagnostic mode. Check battery voltage. After checking the OBD-2 port connector and getting the correct voltage make sure you check the Memory power wire and ECM power wire for the correct voltage. A bad ignition switch will brown out a ECM for example.

Check voltages and wires before replacing the ECM...