thank all of you who have been helping me get my truck equiped with the e4od , it went into limp mode, because the tachometer was not working.
so i changed the tach sensor----nothing
i changed the teca relay ---nothing
i chased the wires --no breaks
i pulled the cluster cleaned the connections-----nothing
changed the fipl-----nothing
changed the vass------nothing
switched the pcm------nothing
changed the trans control mod ---------nothing
what the f%^k
so i took off the teca relay again and jumped it from the power in to the pcm out ----- BINGO!!!!!!
the question now is why do they have the relay?
can i just leave it alone?
i just wounder how many guy's got trans rebuild because of that femal connection
I think the relay handles about 20 amps of power. Simply routing that to the ignition switch will put too much load and cause a failure there. Same reason you have a starter relay instead of routing the battery cable to the starter switch in the column only scaled down. Electric fuel pumps typically draw 20-30 amps peak depending on the make and model and those also require a relay to protect the ignition switch.
Bottom line is you need to have that relay in there. As a temporary fix to get you home, you can just jump a wire across, but its not a long term solution.
I think I did hear of at least one possibly two trucks that hand the transmissions rebuilt over electrical problems like this.
I believe in previous posts from bigjoe, I stated that the TECA should be checked, not the PCM (which does not exist according to the Ford Truck Manual and the wiring diagram...still glad you got it fixed! Why you guys continue to call it a PCM amazes me.