Dangling 3-wire plug in engine compartment (???)

[JGK]

I have an early '98 12v 5spd. I was doing maintenance the other day and discovered a 3 wire lead off the main wiring harness that goes down the driver's side of the motor that's not plugged into anything.



This harness is the one that goes from the back of the motor, along the pump then crosses the front and has the wires to the heater grid. It then goes over to the alternator. The lead I found exits the main group just under the intake horn by the throttle linkage. It is about a foot long and ends in a 3-prong flat weather proof connector. Its got grease and oil in it so it hasn't been hooked up for a while, if ever. The wires going to it are purple with a white stripe, orange with a black stripe, and black with a light blue stripe.



Any ideas before I start digging into the big green bible?



Thanks,

Jay

 

[Evan A. Beck]

THe plug you are describing is the harness for the throttle position sensor (TPS). 5-speed trucks don't have a TPS, but all the trucks were wired for it. The TPS is an input to the PCM for torque converter clutch operation.

 

[JohnE]

I don't believe that manual transmission models have a TPS on the injector pump.

3 wires and the connector location hints to a (missing) TPS.



<em>Many EGR systems on gasoline engines use TPS as part of the controls. Does the 12 valve Cummins do the same? I know the Detroit Series 50 uses TPS data as part of the cooled EGR controls</em>



-John



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edit

That's what I get for stopping to answer an email in the middle of the reply. . Evan beat me to the post. I just remembered the EGR connection, too.

 

[JGK]

John, Evan,



Thanks, guys. I'll tuck it away and ignore it.



Jay