I recently cleaned the throttle body and replaced the 3 sensors on my 96 Ram 2500 5.9l (auto, 4x4). Unfortunately, when I went to start her up I noticed the check engine light was on with error code 24 - tps out of range. I verified I had installed the tps sensor correctly. I then pulled the connector from the TPS and found 5v on the outer contacts, which is normal, but also found I had 5v coming from the center signal wire on the connector (i.e., not from the tps itself) which is not normal. I assume these 5v coming from the PCM is the cause of my error code. I traced this signal wire to pin 23 of the PCM (black) and there were no shorts.

My trouble shooting guide suggests that this is a symptom of a bad PCM but I wanted to check with others before I lay out the $$$$ for a new computer. Is there anything else I should/could check or another way to test the PCM? I know it seems strange that this problem would popup after I messed with the TB and all those sensors. Any feedback would be appreciated!

Thx!

 

if you don't have continuity between any of the three wires, with both ends unplugged, and you still get 5v on the signal wire with the TPS unplugged, that does indicate a bad PCM......

 

Thanks HeyYou!

Just to clarify, by both ends you mean the tps and the PCM connector, right?

 

Correct.

 

It is good to keep a spare PCM handy if you plan to keep the truck a while. I found that out the hard way once when I bricked my PCM with a faulty SCT tune. You can typically find a good used PCM at a reasonable price on eBay or locally at a pick+pay style salvage yard.

 

the pcm may run a bias voltage on the signal wire and that is what you are reading with the connector unplugged. this is normal on all the new trucks. the new trucks measure 5 on the ref, 5 on the signal and 0 on the grd. with the connector unplugged you should set a circuit high dtc. when the signal is jumpered to the grd wire...you should set a circuit low dtc. if this is the case the wiring is good, replace the tps...if the dtc stills sets, replace the pcm.

 

I know these computers control a lot of functions. If I go the used route do you have to make sure there is an exact match above and beyond the year and engine model. For example, do I need to check that the donor truck has the same transmission, speed control, 4x4, non-California emissions, etc???? My buddy had a spare PCM for his 97 Ram with the same engine and when we swapped it in my 96 truck it would just crank..

 

Same engine and trans, and emissions equipment, the rest doesn't really matter. Getting one from a 96 would be best.... I think parts stores sell remans for around 250 or so.... they come with a warranty.

 

Thanks to everyone for their help! More to come.....

 

Great info there! Nice to know, thanks!