T176 Reverse Switch

[montanablueSJ]

Wondering how the reverse lights get 12V+
I looked at wiring diagrams, but it just says goes to neutral safety switch when I follow from taillight back. I don't think I have a NSS.
Does the switch send positive power to taillights directly once it closes when shifted into reverse? Where does it get it from?
Going to take out switch and see if it works, but I'd like to understand first how the lights get lit. Is it recommended/possible to take out switch from below?
Thanks!

[BCRAWLER]

Just checked the TSM and on page 2b-8 it shows #35 as being back up switch. Located on passenger side of transmission body.

[tgreese]

I doubt a manual transmission car has a neutral safety switch. The NSS connection is typically to a ground post coming from the bottom of the starter solenoid. The manual transmission starter solenoid grounds through the fender rather than the NSS.

The backuy light switch on a manual transmission is on the transmission shift top. You'll have to take up the carpets and floor panel to reach it. There may also be a transmission controlled spark (TCS, an emissions device) switch on the shift top.

If you are looking at the '81 diagram from the Tom Collins site, I suspect that is copied from a Haynes or Chilton's manual (does not look like Jeep Corp. stuff). My suggestion is to buy the TSM for your year, which will include the Jeep Corp wiring diagrams. Cheap on CD from Rock Auto, or a printed copy from BJ's.

[BCRAWLER]

That was from my hard copy of the 81 TSM. Shows the switch almost dead center passenger side right below a bolt decribed as the reverse pivot. Suprised me as well for its location. Will check Chiltons for a giggle after work. Wondering if below fill level.

[tgreese]

Not familiar with the T-176 shift pivot, but on the Borg-Warner transmissions, the reverse shift rail pushes on the switch to activate the lights. TCS will be on the top gear rail (forward left corner), if present. The Tremec T-176 is a repop of the Ford Top Loader passenger car transmission, but should be similar to the Borg-Warners.

[montanablueSJ]

Thanks guys, I will take up the carpet and boots and take a look. Looking underneath, I found the single wire for the NP208 dash indicator light, but couldn't feel the backup switch anywhere, guess I have to go from the top.

[montanablueSJ]

I got a look at the top of the transmission by taking up the shifter boot and found the switch and connector: it was exactly where tgreese said it would be!

I tested the switch and it is still good. (continuity across terminals when in reverse, open when not)
I tried jumping the connector pigtail just to be sure, but no lights came on. (I tried with ignition on too, not sure if the power is ignition fed).
I have already checked the bulbs.
I checked continuity from both terminals of the connecter, and got a lot of continuity: I got continuity from connector to both positive and negative terminals of the battery, and the same for both terminals. I’m not sure how that’s possible, maybe I don’t understand the wiring.
I thought the switch worked by sending positive power to the switch, then going to the taillights. When in reverse, the switch closes the circuit and power gets to the bulbs. When not in reverse, it's an open circuit. Is that right?

[tgreese]

I don't know specifically about the T176 trucks. Often these switches connect the powered wire to ground to operate the lights. I suggest you get the diagram and trace it through. Look here - http://oljeep.com/gw/elec/GW_wiring.html