Engine/Transmission (1994 - 1998) orange/blk Mystery switch wire - where

[SDrake]

I have been searching and reading and can't find information I must have seen dozens of times. Pin 54 on the ECM has a orange with black tracer wire coming out of it (I have read) but surely there is a way to find that wire without cutting open the main harness or removing a bunch of stuff to get to the ECM plug. Doesn't the wire run down to the transmission? And if so, where is a good place to look for it and tap into it, or rather cut and wire to the 3 position switch (Mystery switch).



I believe I understand the theory and I have instructions except for hunting down that wire. My truck is the 94 Cummins 4WD 47RH automatic.

 

[Bob Wagner]

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[Skydiver]

I tapped the wrong Or/BK wire at first. Caused the wait to start light not to go out.

No problem. Just found the correct Orange / Black wire.

 

[SDrake]

Where is the orange/black wire

The schematic is pretty hard to read but I see that there is a black orange wire going down to the transmission that is in a group going down the steering column. But the schematic is for a 1999. Is this wire also there on the 94 and is it the one to cut and wire into the SPDT (mystery) swith?



Or do I have to quit being lazy and just go out and track down pin 54 from my ECM

 

[SDrake]

Yea don't want to get the wrong one

Yea SKYDIVER -- I saw that wrong wire business on an earlier post and that is why I just got too lazy to figure out which one and asked if anyone knew of another place to look where the wire is by itself more. Thanks for the heads up though.

 

[Howard Durand]

There is a three wire cable running to the transmission from the PCM. It breakes out of the harness right over the hump in the middle of the firewall.

Reach up above the transmission from below and you can follow it to the plug located near the rear of the transmission. It carries the three wires needed to operate both the TC lockup and Overdrive.

You can fairly easily pick out the orange and black wire for whatever you want to do.

I was able to access it from inside the cab by removing the 4WD shifter.

 

[SDrake]

So that's the wire!

Thanks Howard, -- I saw that wire but all the discussions I had read mentioned Pin 54 and the wire (wires) in the harness running across the rear of the engine bay. I was just not willing to apply a ground to a wire that I was not absolutely sure was the right one. And I just did not know when I would find time to go in and figure it out, so no switch.



My switch will be wired before I take my next trailer trip.



BTW -I am thinking of flushing and replacing transmission fluid with John Deere HyGuard hydraulic fluid, that Joe G and others have mentioned as a way to be free of worries of trannny overheating. The thing that pushed me that way this weekend is that my transmission temp gauge stopped working just as I was maneuvering my trailer into its tight parking spot up a steep hill. A time or two based on the gauge reading I have needed to give it a rest, but this time no gauge



The other time I have temp problems is when I have to go up a mountain road near here with speed dictated by traffic at around 35-40 MPH, so need to keep the converter locked. I am sure I have a thing or two to learn there. If I am hearing Joe right, with the hydraulic fluid I may not have to worry about it. Any voices of experience out there I would be glad to hear from.