The symptom was that my reverse lights were not working, all else seems nominal. Bear in mind this poor car suffered the wrath of a hick from Kansas... I've gotten most systems up and servicable, and am moving into the electrics arena.

Before I wantonly ordered a new reverse switch from IPD or somebody else, I decided to jack the car up and take a look at the whole transmission harness subsystem. Bear in mind this is a 4-speed + overdrive M46 transmission - a rare beasty. Does anyone know the percent of production run for 700's that were made with manual transmissions? I remember hearing 2.5%. Regardless, what I found underneath my car was startling.

There are 4 wires in the wiring harness for the M46 (none for the automatic 740), and I had definite problems here. It was painfully apparent that this was not the original transmission due to junkyard writing. It looks like whoever yanked the old transmission paid exactly no attention to this tranny wiring harness and 4-way connector.

The 10 gauge black wire was severed at the connector with only a few frayed ends protruding from the back of the connector. I whipped up a pair of alligator clips and a 10 gauge black bit of wire, and connected these two eroded wires. Worked great - I finally had the sacred reverse lights - but at a price. Suddenly, the key-in driver door chime no longer worked, and the overhead courtesy light no longer lingered before dimming itself out.

I feel better already for sharing. Any idea why connecting the backup-light circuit hurts some of these other circuits? The bloody wire is a ground, for God's sake not something positively wired.

What I really use is a good diagram and/or description of the wiring connecting the courtesy light up - I think there are 5 wires and I did my best guesstimate for what wire was what. This is the only conceivable place the ground wire connection from the tranny (the ground) could interfere with each other... I think.

I was just ready to blame the Belgians who built this car on general principal. just kidding...

Sorry to rant - thx in advance.

 

The m46 came in the turbo's,m47's came in non turbo's.The black wire from the back up switch is not a ground,it supply's 12v to the back up lights.I think there on fuse #12 What color's are the four wires in the harness?

Dan

 

Its been a while since I've been under there, but I think they were:
10 gauge Black
14 gauge black/red
14 gauge yellow/blue
14 gauge unknown (like the yellow/blue wire, it suffers from Volvo Wire Rot.
The individual strands are corroded but usable, although all of
the plastic jacket is gone.)

I tried using Brakleen on the wires, but it wouldn't get all the grunge off of the wires on the transmission/switch side of the 4-way connection.

 

Back up light sw - Blue/Red 12v from fuse #12 - Black to reverse lights
Over drive solenoid - Yellow from over drive relay - Black to ground
Over drive contact sw - Blue/Black from over drive relay - Black to ground

If you will pm me your email addy I'll send you a complete wiring digram for your car.


Dan