Verlyn Foster
Registered User
I've done a lot of diagnostic work on this 1994 F250 and have discovered a short to ground in the right bank under the valve cover. But, after all the testing and narrowing down of the short, I still can't get the self test output terminal inside the eec test plug to test 0 volts with the key on and no self test engaged. I'm pretty sure the IDM is going to need to be replaced because of the short and I would like to be able to pull codes on this truck, but, can't get the scan tool to do any type of tests. I've tried my MT2500 as well as an OTC Read only scan tool. I have also attempted to pull the codes manually with 0 success. Can anyone tell me the origin of the STO wire? Does it come from the main PCM?