I am working on my 94 4.3 type w and I am getting a persistent code 42. I tried to replace the ECM but that didn't resolve the code. But my question relates to the differences between the 2wd and 4wd. The reason is because I used the body from a 4wd to restore my 2wd truck. So when the body was swapped the factory ECM in the 4wd was used. I'm sure that mechanic did not take the time to swap the ECMs.

When I replaced the ECM i purchased one for a 2wd model. But the PROM I reused would be the one that came out of the 4wd. Are there actually programming differences between the 2 models? Would using a PROM from a 4wd create a problem? Are they any differences with other sensors?

 

I can say that the wires alone are different from 2wd to 4wd in the dash. So I'm gonna assume that the ecm is different. Just because they need different programing for power output during shifts... if they use that... I'm going out on a limb here lol...

But I could be making an *** out of u and me........

 

Thank you! Well, if the wiring is different then it stands to reason that the pin assignments are different, too. I might need to try the 4wd ECM since that's def the wiring in the dash. The engine and sensors are from the 2wd.

 

To whative come across. If they came from the same year, the engine should be the same, so the wires should be the same... difference mostly came for that trans and 4wd