Brake Light Switch, Again?

[rokemester]

Yes I’ve had the white connectors unplugged. Duh, didn’t know brake lights would come on without ignition switch on! Good to know.

[scarceller]

take pin 86 and jumper a wire to 30 then take 30 to the green wire on the white connector. That green wire has power at all times, no need to put key in ignition.

[rokemester]

I jumped a wire from 30 to 86 and installed wiring harness.
Pushed brake pedal, no brake lights. Turned ignition key one click, brake lights came on. Something not right and did not want to blow another fuse by depressing the brake pedal. Disconnected the harness.

[scarceller]

Can you explain what/how you wired the MC Switches? what did you connect to those switches?

Draw a hand written picture of what you wired and post here.

Or please follow these directions carefully for doing a first preliminary test without wiring up the MC switches yet. You should have no wires on the MC switches at this time.

1 - unplug both white connectors from the MC switches
2 - locate the green wire on one of the white switch connectors and verify it has 12vdc with key out
3 - wire that green wire to relay pins 30 and 86, this puts 12vdc on pins 30 and 86 at all times.
4 - wire the other brown wire in the white connector to pin 87 of relay
5 - at this point the brake lights should still be OFF
6 - Now, take pin 85 wire and touch it to a good ground point, the moment you do this the brake lights should come on. No need to press any brake pedal yet.

If you do as outlined above touching pin 85 to ground should activate the brake lights and removing the ground the lights go off.

Confirm this testing and then we can discuss how pin 85 gets wired to the switches next.

[rokemester]

Yes, pin 85 ground, two wires feeding one side of each MC switch. 86 feeding two wires to the other side of the MC switches. I looked closely at the two pics you posted earlier in this thread. The most recent attempt was to jump 12v to 86.

[scarceller]

I sent you email via pelican PM, please check your email.

[rokemester]

Black green side of connector does not provide 12v with key out or with key turned to first position. Must be my voltmeter or the operator. I jumped the black green and black yellow at the white plug and the brake lights came on with key in the first position.

[scarceller]

Plug the switches back in in stock configuration and verify brake lights work.
It's possible you have a fuse burned out?
One of the 2 pins in the stock white connector should have 12v, check both pins just in case.
What year is the car? I'll review the wiring schematics for your year.
And what color wires are on that white connector in your car?

[rokemester]

I followed:

1 - unplug both white connectors from the MC switches
2 - locate the green wire on one of the white switch connectors and verify it has 12vdc with key out
3 - wire that green wire to relay pins 30 and 86, this puts 12vdc on pins 30 and 86 at all times.
4 - wire the other brown wire in the white connector to pin 87 of relay
5 - at this point the brake lights should still be OFF
6 - Now, take pin 85 wire and touch it to a good ground point, the moment you do this the brake lights should come on. No need to press any brake pedal yet.

If you do as outlined above touching pin 85 to ground should activate the brake lights and removing the ground the lights go off.

Yes, have brake lights but Key needs to be at first position to get 12v from black green.

[scarceller]

Just looked at the wiring for the 87 cars, the white connectors should have a green/blue wire that has 12vdc on it with key in RUN or START.

You are correct that the 87 cars only have power to brake lights with key in RUN position.

If you wire up as I outlined above you can confirm that when you touch 85 to ground the brake lights come on and when ground is removed the lights go out? I need to be certain of this behavior before we proceed.

[rokemester]

With more help from Sal I’ve cracked the code (in my dense brain) to get Sal’s relay circuit to work. The big aha moment was to power the relay at terminal 85 on the other side of the coil from terminal 86 which triggers from the MC switches. I had it in my head that black wire 85 on my relay went to ground! The solution was to jump power from 30 to 85. As Sal explained either 85 or 86 can serve as the circuit trigger wire with the other side of the coil getting power. I’ll post some pics of the final install tomorrow. Thanks all, especially Sal!

[rokemester]

Originally Posted by wazzz

You need 12V both for the relay coil and to power the brake lights. You don't need to pull a second wire. Bring the 12V wire to terminal 30 and loop with a small piece of wire between 30 and 86.

Also if I would have understood this post I could have gotten lights faster. Thanks!!





I ended up jumping power from 30 to 85. I mistakenly thought 85 went to ground.

[rokemester]

I buttoned the relay harness this morning. If you do this and mount the relay to the support bar make the wire length longer than usual so it is easier to snake the air hoses back in place.





This project will cause some scraped up hands and one or two expletives!

[rokemester]

I also tacked an operations note on the backside of the ventilation cover so the future owner isn’t cursing the PO for messing with the car. The beauty of Sal’s elegant fix is you don’t need to hack into the wiring harness. It is plug and play.

I added a couple pieces of foam to reduce the relay click with limited success.

[scarceller]

Looks great! Curious where you grounded the ground wire for the 2 MC switches? To what bolt or ground point?
I also really like all the shrink tubing, very clean and safe.

[rokemester]

I used the relay fastening point on the brace for the ground harness. I just dremmeled the lower mounting hole and hole I drilled for the relay.

[rokemester]

This shows the grounding point. I had made the mistake of grounding 85. Now you can see 85 the black wire jumped to terminal 30.