Reverse Light Switch Connection and Return to working

[SP3]

In attempting to restore the Reverse light into operation, I am only seeing the switch/sender on the tranny and no wire with push-on connector in the vicinity. Does this part of the harness run inside the car along the tunnel or underneath the floor pan (exterior of car)?

I see what color original wire is per Curtis’s schematic in Tech Wiki but can’t discern from diagram where the wire is routed from to connect or add into harness to connect.

I assume the switch doesn’t generate 12volts when the shifter is placed in Reverse with the ignition in Run position without wire attached. I checked in this condition with a test light/continuity tester and it did not show tab on switch was hot (12 volts).

Vehicle is 1600

[DAC21]

Here is a reverse light thread that might shed some light.

viewtopic.php?t=24147

[JT68]

It’s a pair of red/black wires that connect to the dash harness below the master cylinders. The two wires are their own little harness
that routes from below the masters, down the tunnel to the switch. That little harness often gets thrown away.

If you jumper the two red/ black harness connectors below the master cylinders, the reverse lamp should be "on". Caution though one of those wires should have +12v so be careful not to touch the chassis. (w/Ignition switch on as I recall)

[SP3]

I only saw one tab for a connector to push on to. With the wire harness I assume the 12v lead goes on the tab on the switch, where does the other wire connect?

Looked at the switch several times and pretty sure I only saw one terminal coming off of it.

[rwmann]

There should be two connectors on the switch, but if you connect the +12v wire to the switch, then grounding the other wire should energize the reverse lamp circuit when reverse is selected.

[JT68]

As above, two bullet terminals on the switch, two red/black wires under the master cylinders. (Bullet connectors there too).

[notoptoy]

I think there are two male spade connectors on the switch,. The "harness" as I recall is just two wires, with female spades on the transmission switch side, and two male bullet connectors on the master cylinder side. If you only have one connector on the switch, I would think one got broken off at some point.

[JT68]

I think there are two male spade connectors on the switch,. The "harness" as I recall is just two wires, with female spades on the transmission switch side, and two male bullet connectors on the master cylinder side. If you only have one connector on the switch, I would think one got broken off at some point.

I think we are both correct, yes, I think the early 4-speed switches had 2 spade connections, all the later trans had two bullets. Yes, it there is only one spade, it sounds like an early trans with one spade broken. Best of luck!

[SP3]

Something is not adding up and hopefully a minor oversight by me.

I installed the Reverse switch with two leads on it. Made up a harness to connect the 2 red/black wires under master cylinder to the switch on tranny. With ignition switch turned all the way to Run and shifter in Reverse, no rear light.

I then bypassed the tranny switch and connected the 2 red/black wires under master cylinder and still no reverse light.

I confirmed 12v live on one the two wired under master and also 12v in the light socket with key on.

The 1073 bulb appeared burnt and I could hear particles rattling around when shaking the bulb. I replaced the bulb with two different new 1073’s and still light operation.

If getting voltage to the socket it seems like the light should work.

[JT68]

Sounds like you are almost there:

"If getting voltage to the socket it seems like the light should work."

yes, you need 4 things for the bulb to light:

1. a (correct) good bulb (test it on a battery) There are lots of bulbs about, it needs to fit the socket correctly (see 3 & 4)
2. +12V at the socket (sounds like you have that)
3. Clean, secure wire and socket connections(every one)
4. Secure ground connection (see number 3)

If you have 12V at the socket and a good/correct bulb, it is #3 or 4.

Your test of shorting the two connections under the master is a valid test, the reverse lamp should light in that case (key on). Sounds like corrosion, bulb fit, or another connection issue.

[DAC21]

Something is not adding up and hopefully a minor oversight by me.

I installed the Reverse switch with two leads on it. Made up a harness to connect the 2 red/black wires under master cylinder to the switch on tranny. With ignition switch turned all the way to Run and shifter in Reverse, no rear light.

I then bypassed the tranny switch and connected the 2 red/black wires under master cylinder and still no reverse light.

I confirmed 12v live on one the two wired under master and also 12v in the light socket with key on.

The 1073 bulb appeared burnt and I could hear particles rattling around when shaking the bulb. I replaced the bulb with two different new 1073’s and still light operation.

If getting voltage to the socket it seems like the light should work.

Bulb not making proper contact in socket?

[theunz]

If you are getting 12 volts at the socket but the bulb is not working and known to be good, then you must have a ground problem. There are two wires going to the reverse light, a hot and a ground. Use a test light hooked to each of them to determine if the ground is good. If good there then touch one end of test light to the center of the socket and the other end to the side of the socket. If the light doesn’t light try scratching the side of the socket. If it does then try cleaning the side of the socket. Actually you might try checking the socket before checking the wires to save time. If you determine that the socket is loose you can put a little solder on the side of the bulb and then sand it down for a tight fit.