66 belvedere back up lights wiring route

[john hoover]

I removed 3 speed trans and installed 4 speed. I have a new backup light wiring harness but dont know where to route the wires from firewall to backup light switch. Anybody know the physical route the wires were located? thanks

 

[66383]

Glad you joined us. If you don't have a factory service manual, you need one!

 

[john hoover]

Glad you joined us. If you don't have a factory service manual, you need one!

Yes, I have the service manual, but in this case, the manual shows the wiring diagram, but not the physical route.

 

[john hoover]

still looking for proper placement of wire from bulkhead to switch on transmission, anyone?

 

[mopar 3 B]

Need a clarification. Wire location at bulkhead or routing of wire to the transmission switch? I can not remember as it has been years. But I believe there was a firewall clip and transmission tail shaft wire clip. For as many times I reattached the darn thing I could do it in my sleep if the car was here.

 

[john hoover]

routing of wire to the transmission switch, does it go under console or down floor beside tunnel? not real important, just trying to follow factory

 

[Belle66]

My 66 Bel with the 727 trans, has the reverse light switch mounted to the steering column. The wires travel along the edge of the driver's side floor along with the brake light wires. Not sure how to address back-up light switch on the trans. I do have one wire coming from the trans to the starter relay which is the neutral safety switch.

 

[Ceedawg]

Ok, went thru the same thing on my 66 car. First off the 4 speed has its own underhood wiring harness. There is a 3 prong connecter under the master cylinder. The 2 wire trans cable plus the oil sender wire attach to this connector. I made my 3wire connector out of a headlight cable and later model 2 wire bl off of my Duster 3 speed trans.
Also you need a case grounded relay

 

[mopar 3 B]

View attachment 879610 Ok, went thru the same thing on my 66 car. First off the 4 speed has its own underhood wiring harness. There is a 3 prong connecter under the master cylinder. The 2 wire trans cable plus the oil sender wire attach to this connector. I made my 3wire connector out of a headlight cable and later model 2 wire bl off of my Duster 3 speed trans.
Also you need a case grounded relay

What was the purpose of the case grounded relay? The switch that screws into the transmission only completes the circuit. A simple toggle switch would do the same. I see no reason for a relay.

 

[Ceedawg]

What was the purpose of the case grounded relay? The switch that screws into the transmission only completes the circuit. A simple toggle switch would do the same. I see no reason for a relay.

The starter relay has to ground to work and engage the starter. Autos have a 1 prong, for grounding the relay (3 in later years for backup and ground) The 4 speed has a 2 prong for backup lights only. You can use the non grounded relay by making a jumper and grounding to relay bolt or just solder up the gap like the factory did. Early stick cars have a grounded case. Later on they put the grounding switch in the clutch pedal for safety reasons.

 

[Ceedawg]

Went back and re-read you post. The wires run down between tunnel and trans. Did you have a manual 3 speed? If so the wires should all be the same.

 

[Ceedawg]

Diagram

 

[mopar 3 B]

The starter relay has to ground to work and engage the starter. Autos have a 1 prong, for grounding the relay (3 in later years for backup and ground) The 4 speed has a 2 prong for backup lights only. You can use the non grounded relay by making a jumper and grounding to relay bolt or just solder up the gap like the factory did. Early stick cars have a grounded case. Later on they put the grounding switch in the clutch pedal for safety reasons.

The 3 speed manual in 66 also used the 2 prong. No safety switch. Would start in gear with the clutch released if you so chose. Backup lights never went threw the relay.

 

[Ceedawg]

At first I thought you had an automatic trans, my bad, that's the reason I wrote about the "starter" relay being different. When going from 3 to 4 speed there should be no changes in the wiring, unless you bought an auto backup light harness. If so the diagram I furnished shows whitch wire you need to splice your original wires off trans back into.