Trans Am Information > Electrical

DIY: Power window 4 relay setup (w/pictures)

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I finally took some time to make a little DIY on the 4 relay setup. I'm by no means a electricals guru, so feel free to share any errors that I could made or share your feedback on your work.
I will not make our sell theses kit simply because its somewhat easy to do and i'm not doing it for the money.
Just sharing my experience.

This DIY will keep your cost down and make it easy.

Bare in mind I no longer own a T/A, so I make this setup with my diagram and what's left in my brain lol

Ok, lets start:

1-What you need!
4x Bosh style relay and pigtail
8x female terminals
8x male terminals
1x 30amp fuse
some wire:
Red:10-12 gauge
Black: 14-16 gauge
Electrical tape
Solder iron

- Big eye terminal and inline fuse if you are installing this setup directly to your battery
or male or female (can't remember exactly) if installing directly to your fuse box. (preferred)

2- The relay and wiring!
I decided to make a little bracket from some left over carbon fiber board I had.
These relay can be held together by snaping all the pigtails together, so it can save you little fabrication.
I bought my relay and pigtails on eBaY (seller id: install_depot )
Upon receiving my relay, I didn't like the color coordination of the pigtail, so using a sharp tool I made a few changed. (Thats a personal preference) You can keep the color configuration, just take good notes.
I also removed the wire from pin 87a. (middle), its not needed for this setup.

3- Ground!
First thing I did its to make the ground.
Take all 4 ground from the relay (85) and soldered them to one wire (14-16 gauge).
Then, use electrical tape or heat shrink tubing to protect your exposed wire.

4- Positive 12 volts!
Same as the ground, now take all 4 positive from the relay (87)
Now its a good time to measure your red wire depending if you are connecting this wire to your fuse box or battery. (if gooing directly to your battery, I suggest an inline 30 amp fuse to be installed)
Also, take a bigger gauge of wire like 12 or 10 gauge.

5- Identification!
Now, the basic and easy wiring is done.
I used 8x female terminals and crimped them on each end.
Also now its a good time to labelled each wire. This will make connections and troubleshooting easier.
Driver UP to window motor (30 on the relay)
Driver UP to switch (86 on the relay)
Driver Down to window motor (30 on the relay)
Driver Down to switch (86 on the relay)
Passenger UP to window motor (30 on the relay)
Passenger UP to switch (86 on the relay)
Passenger Down to window motor (30on the relay)
Passenger Down to switch (86 on the relay)
You can refer to my diagram

6- Your factory harness!
Now removed your center console and unplug your car battery.
Once your center console removed, you will have access to your power window harness.
Unwrap your wired, and your will see 5 wires.
4 of them will need to be cut.
The one that doesn't need to be uncut if typicaly either red w/white line or pink, its goes from your existing relay under the dash to the middle of your switch.
The power window color coded wires should be the same through the years.
Driver UP: Dark blue
Driver Down: Dark Brown
Passenger UP: Blue w/white line
Passenger Down: Light brown

7- Cutting and labeling
Now that you got access, cut your wire and labelled them.
Its a personal preference were to cut. Also extra lengh of wire may be needed.
I used my 8x male terminals and crimped them to the factory harness.

8- Assembly!
Now its time put connect everything.
Hopefully you labelled all your wires! This is easy when all the labels are made.
Simply connect them all.

9- almost done!
Yup....almost done!
Make sure all your connection are tape with electrical tape to avoid any electrical short!

10- Last little things!!

-Replace your circuit breaker in your fuse box (top left corner) with a 30amp fuse.

--Optional but for best result, install new ground from your window motors to the frame.
You need to remove your door panel to gain access to your motors.
It take a little more time, but adding new ground will help your motor.
Its optional, and up to you this step is done our not.
Use gauge size gauge like 10-12 ga. or ground strap for best result

Reconnect your battery and test your power windows setup.
If everything is plugged correctly, you will be very happy with the result!

Reference diagram:

The result:
Its my only video, and my power window were not brand new, they were old parts box thaught to be non-working.

My original setup in my 79 T/A.

This is a GREAT write up.  Thanks!

I do have a question for you please.  Is it really personal preference if you get the power from the fuse-box or directly from the battery or is one preferred choice over the other?  If I go directly to the battery do I still need to change the fuse in the fuse-box to a 30amp?


Thank you for detailing this project with pictures. This makes it easier to see how you make the connections. A lot of us in DIY Land are a little scared about cutting into expensive wire harnesses and /or frying them. I too want to know if its better to get power from the battery or connect power from the fuse block. I already bought the #10 gauge wire and a 30 amp fuse but that would require drilling a hole through the firewall, right?
                                                                                                                                          OrangeCrush79  (Jon W)

I did this to my sons TA for the locks and put remote lock unlock and trunk release on it
Cool post

Thanks for the write up!  One more question though;  is the oriiginal GM relay under the dash still used with your set up, and if so, why?

Thanks again


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