77 T150 third gear sensor - JeepForum.com
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post #1 of 6 Old 06-17-2003, 08:15 PM Thread Starter
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1994 YJ Wrangler 
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77 T150 third gear sensor


I had to take my 77 CJ5 into a smog only test station and I failed because of the third gear position switch. Everything is fine but it won't pass the visual. The switch works fine but the harness has been cut/ripped off. I just have the wires hanging there. I tested the switch, it works but it has two wierd poles. Can I get a connector for them from somewhere. Who carries these? How can I connect them permenantly, like factory would be nice.

1994 YJ 4.0L 5spd
SOA, 5100 Bilstein, TJ Flares, 35" BFG AT, 8.8, SYE, D30 truetrac/chromo, 1" MML
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post #2 of 6 Old 06-17-2003, 09:42 PM
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Are you sure that the switch engages in 3rd? Call me silly, but it sounds like the reverse light switch.
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post #3 of 6 Old 06-18-2003, 05:12 AM
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I have rebuild those trannys but I have never seen and sensor in them you have to talking about the BACK UP LIGHT SWITCH.

AMC 360 bored 30 over
2 over cam, high rise intake, EB carb
T 18 trany, Dana 20 transfer
one peice axels
35" M/T's
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post #4 of 6 Old 06-18-2003, 08:15 AM Thread Starter
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This is what I always thought it was also, the above description is what the smog guy at the test only station informed me it was. Besides the switch part does anyone know what I am talking about? I was told this switch lets a solenoid know third gear is engaged and opens a vacuum that advances the timing. he won't pass the vehicle until its hooked up.

My friends 74 CJ5 does not have this switch, it only has a reverse switch.

Just working off what I was told at this point.

If it is a reverse switch where can I get the connector for the plug? That is what I am really after.

1994 YJ 4.0L 5spd
SOA, 5100 Bilstein, TJ Flares, 35" BFG AT, 8.8, SYE, D30 truetrac/chromo, 1" MML
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post #5 of 6 Old 06-18-2003, 08:58 AM
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Fellas it is a switch that is activated in high gear. It's part of emissions control and is called transmission controlled spark system. It activates a solenoid only in high gear which disables the vacuum advance to the distributor. In theory the idea is to reduce oxides of nitrogen by lowering the combustion temperature on the power stroke.

As far as harnesses go you'll have to make your own. Find a wiring diagram and use plugs you can purchase at NAPA. They won't be factory, but will look factory. I have diagrams of how the vacuum is plumbed, but not the wiring.
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post #6 of 6 Old 06-18-2003, 10:00 AM
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that switch was used in calf and altitude engines only

1978 cj-7 had since 1979
401 .030 over- full floating flat top pistons
crower solid cam 292 dur .500/.510 lift
turbo 400 tranny 2500 stall
model 20 transfer case
aj delux glass body
4" lift
dana 30 frount
dana 44 rear
4.56 gears
13.461 @ 92.45 mph on 37" super swampers on 1/4 mile
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