wiring problem -power windows.

[seasand77]

I have 1971 Delta 88 with power window problems. To test the motors, I'm going to run a jumper from the battery to the motor, but don't know if my system supplies 12v constantly, or does it switch the ground side of the circuit? I can't even find a reference in chassis service manual. Thanks

[rocketraider]

The power window and seat stuff is in the Fisher Body manual.

If none of the windows work:

First check the power accessory feed circuit breaker. It's at the top left of the fuse block, labeled "ACCSY-PWR RLY" and if it's bad, you can find one at a parts store. It's a 40 amp breaker and plugs in same as a fuse. This circuit is fed straight from the battery via the junction block on the firewall and is hot all the time.

Next- check the "DIR SIG BACKUP" fuse at the fuse block. The ignition relay trigger is thru this fuse. The pink wire to the relay plugs into a terminal just to the left of this fuse. If it's unplugged windows won't work. This terminal and fuse are hot only with ignition switch "ON".

Next check the ignition relay located behind the left kick panel. Three wires- check with relay plugged into harness.

Orange/black stripe is the power feed from the circuit breaker and should be hot at all times.

Red/white stripe is the relay output to the power window switches. Turn ignition switch on and check for voltage here with test light. If no voltage, then go to>>>

Pink or tan is the trigger from the ignition switch. With switch on, there should be voltage here. If test light lights, ignition relay is bad. If it doesn't light, check fuse or plug as described above, or there's a break in the wiring somewhere between fuse block and relay. If relay is bad, you may have to find one in a junkyard.

There should also be a junction block behind the left kickpanel that all the power accessory circuits (P window, P seats, P top) plug into. Power window circuit feed wire may have come loose here.

If individual windows don't work, check the motor by running a 12v jumper to each terminal on the motor. Motor grounds to the door structure and the motor terminals are for up and down windings in the motor. You may find it will work one direction and not in the other.

Check the switches by checking for voltage at the center post of the wiring pad (red/white stripe wire). The jumper across to each output wire. If motor works, switch is bad. If no voltage at red/white wire, there's a wiring or power feed problem. I've often found broken wires in the rubber conduit from door to body.

If you have to replace motors, there's a neat trick for that too that will save you having to take all the regulator and linkage loose. If you have to replace motors, we'll go over that in a separate post.

[seasand77]

Glenn: Thanks for the instructions, but did it answer the question about the voltage configeration?

[rocketraider]

Thought it did... The two wires to the window motor are both hot wires, controlled by the window switch. You have a 12v source to the switch (the red/white stripe wire), then the switch directs it to the "up" or "down" motor winding. The motor grounds to the door structure thru its frame.

So when you actuate the switch for "up", voltage travels thru the switch to the "up" winding and likewise for "down".

[seasand77]

Glenn-It looks like I need to replace two of the motors. What's your special solution? Do you have anything in the Fisher body manual that tells how to wire the drivers side 4 position operator after someone has taken the terminals apart?

[rocketraider]

Shooo- I think I'd try to find another switch pad and splice it in. You can get one from about any late 60s/early 70s GM car with the switch on the door panel, and a lot of B-body cars had power windows by that time. Are the hook terminals OK or are they bent up pretty bad? Should be shaped like a ?.

Here's the order and colors for the master switch wires. This is out of the 1972 FB manual, but the 73,74 and 76 are the same so 71 and 75 should also be the same. GM used this PW color coding for many years.

Red/white stripe is the feed and goes to the short post that is in the centerline of the switch. The long one is a locator and retaining pin.

Left front door window: brown is "down", dark blue is "up".

Right front door window: brown/white stripe is "down", dark blue/white stripe is "up".

Left rear quarter window: purple is "down", dark green is "up".

Right rear quarter window: purple/white stripe is "down", dark green/white stripe is "up".

Switch order in the terminal pad is LF-RF-LR-RR. The feed post should be between the LF and RF window switches.

If you need to replace motors in front doors, the FB manual has a template for drilling holes in the door structure to access the motor mounting screws without taking the whole regulator out of the door. The quarter windows have to remove the regulator from the car, and is a job I tend to farm out to a glass shop. I don't trust those counterbalance springs to not cut my arms off.

PM me with a your mailing address and I'll send you a copy of the template and instructions. I don't have a scanner, shame too because the template is large enough it would scan good.