O/D Switch Invert Mod *Supplemental*
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Record Breaker
Joined: Sep 2015
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O/D Switch Invert Mod *Supplemental*
I finally got around to doing this mod, it was low on list. I have a few tidbits to pass along...
My truck is a '99 but it had the yellow wire , not the dark blue with white tracer. While I was checking to make sure it was the correct wire, I was checking voltage. I had some strange readings, 12v on the yellow, with ignition on, but in "start" AND in "R, D, 2, 1." The voltage dropped to zero in "P, N." This was obviously because it was being grounded through the start relay and grounding the signal. But why the 12v in the other positions, is it going to cause it to switch in and out of OD when shifting? No. It must be some vague transient voltage. It works fine in my truck.
Also, the or/wh wire and a blk/gr wire are all by themselves. Mine were on the driver's side of the column, twisted like cat 5 cable, in black shrink tubing. Those two go back to a 2-pin connector clipped to the steering column. These are actually the only other two other wires you want, the or/wh is the signal and the blk/gr is a ground (which I used for my relay and signal ground).
So,
Yellow wire is "start" positive 12v to the relay coil
Blk/gr is ground for relay coil AND OD signal terminal on relay
Or/wh is signal out to the PCM from the relay
Mods- feel free to add this to the DIY thread on this that already exists...
My truck is a '99 but it had the yellow wire , not the dark blue with white tracer. While I was checking to make sure it was the correct wire, I was checking voltage. I had some strange readings, 12v on the yellow, with ignition on, but in "start" AND in "R, D, 2, 1." The voltage dropped to zero in "P, N." This was obviously because it was being grounded through the start relay and grounding the signal. But why the 12v in the other positions, is it going to cause it to switch in and out of OD when shifting? No. It must be some vague transient voltage. It works fine in my truck.
Also, the or/wh wire and a blk/gr wire are all by themselves. Mine were on the driver's side of the column, twisted like cat 5 cable, in black shrink tubing. Those two go back to a 2-pin connector clipped to the steering column. These are actually the only other two other wires you want, the or/wh is the signal and the blk/gr is a ground (which I used for my relay and signal ground).
So,
Yellow wire is "start" positive 12v to the relay coil
Blk/gr is ground for relay coil AND OD signal terminal on relay
Or/wh is signal out to the PCM from the relay
Mods- feel free to add this to the DIY thread on this that already exists...
Thanks.
Grand Champion
Joined: Apr 2010
Posts: 5,011
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From: Meeker, CO
To visualize it, or even see it by actually doing it, hang a test lamp across the terminals of the battery and measure the voltage from battery negative to the grounded side of the lamp -- it'll be right near zero. Now lift the lamp wire away from battery negative, leaving the positive side connected, and when you measure the voltage on the formerly grounded side of the lamp you'll find battery voltage there.
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Record Breaker
Joined: Sep 2015
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Likes: 4
Well familiar with open voltage and such, it's just that I didn't expect to see it in "run." Looking at the wiring diagrams, that yellow wire should only have voltage on it in "start." That's why I figured it dropped to zero in neutral and park, it was being grounded (prob through the neutral safety switch).
P.S. Because I am somewhat ****, somewhat weird, and only somewhat here, I put a switch in the relay coil leg, just so I can disable it, should I so desire.
P.S. Because I am somewhat ****, somewhat weird, and only somewhat here, I put a switch in the relay coil leg, just so I can disable it, should I so desire.