Tech Reference Page #12
Power windows in 64 (part 4)
wiring the relays
Authored by Wes Vann, August 29, 1997
Here is where it all comes together and a whole bunch of questions get answered.
The first thing to answer is why I'm not just wiring up the power window switches like the factory. Why the dang relays? First you have to know how the factory does it.
The factory wiring has voltage to the door switches at all times (that the ignition is turned on). When you work the switch, the voltage then goes directly to the motor. This means that the large amount of current that the motor needs has to go through the switch. This is why the switches don't last very long! This also means that the switches have to have large wires to them. When you want to roll down the shotgun window with the switch on the drivers door, the large wire has to go from the drivers door all the way to the motor in the shotgun door.
One of the things that I was out to do is have the alarm system roll up the windows (and lock the doors). To do this you need a special unit that you can buy from the alarm company that does two things. One is that it has a timing circuit that allows enough time for the window to close if all the way down. Another thing that it does (and it's REAL important) is monitor the current to the motor to "sense" if the window is up (and the motor is straining). This prevents the motor from burning up by not trying to roll up a window that is already rolled up!!
If I used the factory method of wiring, I'd have to have additional large wires running into the doors.
What I did was get some relays (Bosch) and mounting blocks.
I wired the input to the switches in the doors to ground (and not power). The relays will have power wired to them and when the switches are worked, they select the relay. The relay then sends the voltage (through a large wire) to the motor. I can attach the alarm unit to the output of the relay.
I wanted the relays to be in an assembly that was easy to service if any of the relays go bad. I chose to mount a total of 8 relays into the assembly. Each door window requires two relays (up and down). Two relays will be for the door locks. Two relays are just extra and may be used as an ignition disable.
I made up a bracket that would hold the relays and also "buss" strips for the electrical connections.
What this photo doesn't show is that I latter added brackets for a third "buss" strip.
The reason for the thin "towers" is that I needed room for all of the wires. Once the whole thing is wired, I can unbolt the hardware from the metal bracket without disconnecting the wiring.
I wired the complete assembly on the work bench and kept notes as to what had to get connected to the buss strip once the assembly was mounted in the car. There are only 6 of the relays installed here and I hadn't added the third buss strip yet. All of the wiring is where it can't be seen except for those two green wires.
I added the third buss strip and wired it up to the "extra" relays. Then I mounted the assembly behind the glove box (does anybody really put gloves in their glove box?).
Then I hooked up the wires from the doors.
I hooked up power to the assembly and everything worked!!
return to part 2 Modifying regulators
return to part 3 Boots and wires to the doors
go to page #5 Making door panels
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