Possible.... I wonder though, HOW does the pcm decide if there SHOULD be a temp sensor???? Is it purely programming? If that were the case, then I would expect your truck would have had this issue right off the dealers lot.... I suppose you could try reseating the PCM connector, and cleaning it up nice, see if that makes any difference.

 

Well I have done that in the past, and no change occurred. I actually snipped the trans temp line that went to PCM connector #42, however I have not checked to see if the code popped back up or not.

 

Is there any way to check if the O/D button is shorted or open?

 

Yeah, pull it out, and put a meter on it. It's a momentary switch. Just sends a signal to the PCM to change state.

 

Well I did that, the switch receives power, and there is continuity between the connectors for the lamp in the button, and there is continuity when I press the button.

 

So maybe a wiring issue, or.... PCM.

 

Any way to diagnose either of the two? I am not great at diagnosing electrical issues. Also, my truck has OBD1, while the scanner I used is OBD2, can that cause issues?

 

Well, if your scanner will read the PCM, then it apparently supports OBDI as well.....

Switch is just two wires. 5 volt feed from PCM, and a return from the switch back to the PCM. Looks like it's a shared feed with other sensors as well, so, just make sure you got the 5 volts (key on) on the Black/orange wire. And verify you get 5 volts AT the pcm on pin 10. (orange/white wire.) If you aren't pressing the button, there shouldn't be ANY voltage at pin 10. (pcm needs to be plugged in for this test.)

 

Do I just stick the probe into pin 10 on the PCM?

 

Should be able to go into the hole for that pin from outside, just gotta make sure it touches either the copper in the wire, or the connector crimped on the end of it.