Wiring up power windows and door locks

[75chevyk20]

Hey so I'm new to this thing, this is actually my first post. I was wondering if anyone out there had a wiring schematic or knowledge of the power windows and door lock wiring on a '77 c20. After my wife backed my tow mirror into a poll, ripping holes in my door, I found a set of good doors with collapsible mirrors, for $30. This set of doors is out of a '77 c20 with power windows and door locks. To wire these up is it just a matter of running power and ground or do I need to buy any relays or other miscellaneous parts to get these working? Any help is appreciated.

[Captkaos]

The wiring diagrams are in the Tech section along with the manuals for each year.

[frotosride]

If you want the windows to move at a slowest speed possible then factory wiring will work great but If you would rather upgrade a little since you are running wires either way, I'd recommend relays. Currently the factory switches carry al of the load and crate a lot of voltage and amperage drop just simply sue to their design which is poor if you have ever opened one up. Four relays and a ground off the motor and you will one have fast powerful window action but also the electric motors will last longer due to not being starved for power. I will look up the wiring diagram the I'm doing and you can see how simple it is. Jusst make sure that you get quality relays...its a must.

[frotosride]

Here's the diagram that I'm using and many have had a lot of success with. It's simple to se how using the relays to send full power is a drastic benefit over the factory switch. the best thing is that you maintain the switches and use them as switching power for the relays.

[frotosride]

Ok, so after getting farther along with this install with my truck I noticed a problem with the above wiring diagram. It may actually work for the intended vehicles but the ground from the motor to the frame will not work to complete the circuit in the type of motors on our trucks. Don't worry, I found the problem and the simple solution as well.
Using 5-pin relays allows terminal 87a to be connected to terminal 30 when the relay is de-energized. By simply running a from 87a to the truck will complete the path for the opposing relay's circuit.

I modified the wiring diagram to reflect a circuit that will actually work.

[454Man]

Thinking I may try this.

What's under the hood??? If you have to ask maybe we shouldn't race...

[bd]

I instituted that change about seven years ago using my own design.  First time in the life of the truck the windows worked correctly!  Highly recommended modification!   

[75chevyk20]

Thanks I will definitely be doing this! What is that existing relay there? What do you use to mount all these relays?


Sent from my iPhone using Tapatalk

[75chevyk20]

Also to wire in the passenger side window switch would you just splice in to the wire coming from terminal 86 on the third and fourth relay so it goes to the master switch on drivers door and to the passenger side window switch?


Sent from my iPhone using Tapatalk

[bd]

Thanks I will definitely be doing this!  What is that existing relay there?  What do you use to mount all these relays?

The relay at the top of the diagram doesn't exist in our trucks.  In the original factory wiring, power (B+) runs directly from the fuse box.  Refer to the wiring diagram, below.

Use interlocking sockets to mount the relays under the dash.  Use 10-gauge wire to connect relay terminals 30 to the motors (or match the existing 12-gauge wire size).  Use 10-gauge wire to bring fused B+ into relay terminals 87.  Use 10-gauge wire between relay terminals 87a and ground.  And, use the existing cab harness to control the relays (terminals 85 & 86).

Also to wire in the passenger side window switch would you just splice in to the wire coming from terminal 86 on the third and fourth relay so it goes to the master switch on drivers door and to the passenger side window switch?

For the passenger window, disconnect the brown and dark blue wire pair from the right window motor and reconnect them to the control circuits of relays 3 and 4.  For the driver window, disconnect the brown and dark blue wire pair from the left window motor and reconnect them to the control circuits of relays 1 and 2.  Connecting the wires in this fashion maintains the original functionality of the left and right window switches.

[frotosride]

I did mine exactly like the diagram above by using the existing switch power as switching power for the relay and ran a new positive to 87 and grounded 87a. ooooh, the difference. without the truck running the driverside window wouldn't even roll down (that's with a switch that is less than 6months old). The passenger side is getting it baby... either way will work but I'm drawing power directly from an isolated positive post under the hood with the alternator supplying directly to it as well as the voltage sensing line attached to it. Just make sure that you ground 87a for a true ground because that is where the switches fail. If I can figure out how I will put up a video so you can see drivers vs passenger window.

As for the driverside control for the passenger window, you can just use the leads tied in with the switching power from the passenger switch. I pilled the wires directly out of the passenger switch assembly and crimped and soldered female ends..less wires to run.   I modified the other diagram to give you a better picture of what you are actually dealing with. 

[frotosride]

Interlocking sockets.
Then get relays with mounting tab.

[frotosride]

bd, where do you get good diagrams like that. The best I got is old Haynes repair manual.

[bd]

bd, where do you get good diagrams like that. The best I got is old Haynes repair manual.

The wiring diagram I posted is from a factory manual.  I posted it just so 75chevyk20 would have access to the original wiring diagram for windows and door locks for comparison purposes.

I agree that the newly added B+ feeding relay terminals 87 should enter the cab via a dedicated, protected 10-gauge lead from the engine compartment as you have done.  I think the only point on which we differ is in wiring the control circuits for relays 3 & 4.  You propose running redundant wires from both the driver and passenger switches to control the two right window relays, whereas I propose controlling relays 3 & 4 solely from the passenger switch.  The difference in approach is subtle with identical outcomes.  ...Although, your method might allow for easier diagnosis should the window ever stop functioning, Heaven forbid.   

Either way the wiring modification makes a tremendous improvement to window function!   

[frotosride]

Oh yea...big difference. I actually only ran two wires from the right switch to the relays. the other two were the factory wires that originally ran from left window to the right switch. I simply removed the driver side control from the right switch and pulled them back into the cab, splicing them into the same wires that I ran from the right switch to the 85 on relays 3 & 4. But like you said it aids in trouble shooting this way. Most likely it will be a relay because most but the cheapest relay they can find...which I am guilty of as well many times.

75chevyk20 I deleted the first diagram so its not confusing. I also edited the correct one to show the passenger switch and the only wires you will have run into the passenger door. Any questions or issues just ask. Oh and don't get the cheapest relays, Bosch is likely the best ones to get and make sure that are 5-pin.