DodgeTalk Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
Where the wiring harness located on a 1997 4x4. My truck had a nv4500 swapped into and i want my check engine light off and i dont know where exactly the harness connector is.
 

·
Registered
Joined
·
5,138 Posts
You need to get a pcm for a manual transmission, nothing you can do with the harness will stop the fault codes.
 

·
Registered
Joined
·
29 Posts
You need to study and understand the wiring diagram for the automatic and maybe you can fool the pcm with a resistor or other items. The harness should be on the left side next to the trans.
 

·
Registered
Joined
·
268 Posts
That check engine light will be on for the rest of eternity, since the transmission is not returning any expected values to the PCM. This is what happens when you second guess the original engineering.
 

·
Registered
Joined
·
29 Posts
That is why he needs to duplicate those values, he just needs to find out what they were. If someone can build it the someone can fool it.
 

·
Registered
Joined
·
268 Posts
It's not that simple. The transmission is sending all kinds of data to the PCM. Input speed, output speed, detected slippage, which gear is commanded, which gear is engaged, lockup commanded, lockup engaged, variable line pressure, prime state, oil temperature, etc., all of which are used to calculate sets of expected data (PIDS). Sticking a resistor on is not going to cut it. Very few of these data points are read as a static voltage, rather as a variable frequency signal that is reduced to numeric values and related to data tables in the PCM. Assuming you were able to somehow fool the PCM into turning off the CEL, it would still be missing expected data, and would trip the limp-in mode flag after a certain distance, which would turn the CEL on again.
The solution would be to find a PCM from the same model truck that had that transmission installed (if it ever was), or alternatively, flash a PCM with the correct firmware, which would be essentially a wildcat operation, as no dealer will flash a PCM with non-stock firmware. The swap itself is technically illegal from an emission standpoint, as it's not a certified combination anymore.
 

·
Registered
Joined
·
29 Posts
That is true in later vehicles. That year does not have that much data. I have been in the repair business over 50 years and I have rebuilt and modified dozens of those transmissions. I have also converted some to Diesels. It can be done, those are just 727 torqueflite transmissions with an overdrive added on the back, and a lockup clutch. To explain to the OP how to go about here is too difficult going back and forth. He needs to find help if he needs it in his local area. I have an advantage as my brother is an electronics engineer and I learned from him. He was designing modules like ecms and the test equipment for them many years ago for military aircraft.
 

·
Registered
Joined
·
268 Posts
The PCM firmware is designed for an automatic. It's looking for drive, reverse, park, etc., which don't exist. It's trying to switch solenoids that aren't there. There's a whole range of error conditions that will set a CEL, either immediately or a thousand miles down the road.
 
1 - 8 of 8 Posts
Top