Oliver

iTrader: (4)

I am having some issues with my brake lights not working. I have a 1987 TII. It is currently missing the cpu. I am wondering if the cpu has anything to do with my brake lights. I have power going in and out of my brake light switch, but no brake lights. Any input is appreciated.

rxtasy3

iTrader: (2)

cpu has no control over the brake lights.

satch

iTrader: (1)

As you probably already know there are two wires connected to the Stop light switch on the brake pedal.The W/G wire would be the wire which has voltage on it when the brake pedal is depressed. This wire then goes to the Stop light warning relay in the CPU. From the CPU comes a Green wire that then runs to the brake lights. If you wanted to bypass this relay since you don't have the CPU then you could just connect the W/G wire to the Green wire. The relay in the CPU has the ability to sense if one of the brake lights is out and would warn you of this by turning on the brake light warning in the idiot light cluster. There would be four wires running to the relay in the CPU and two of these would be the W/G wire and the G wire so just connect these two for the time being.

Oliver

iTrader: (4)

I highly enjoy free fixes, but also need a cpu to control hazards and turn signals. Thanks again though satch. I believe I've found one!

Oliver

iTrader: (4)

I found a cpu, no thanks to somebody trying to mess with my posts.

Oliver

iTrader: (4)

odd....i just plugged mine in, and now I have working tail lights.

satch

iTrader: (1)

I wonder if you could do me a favor and briefly disconnect the largest plug to the CPU and try to turn on the tail lights. In the pic I provided, circled in red is the R/B wire from the headlight switch. I think something fishy on this wire was interferring with your tail lights possibly. I would very much appreciate it if you test this theory out as it would help others who might be having similar problems as yourself.

Oliver

iTrader: (4)

Did what you asked. The brake lights did not work after. Plugged it back in, and they came back on.

satch

iTrader: (1)

I understand that the brake lights run throught the CPU on an S4 but you previously stated the tail lights suddenly worked and that is what I was questioning or did you misstype and you meant to say brake lights as opposed to tail lights?

Oliver

iTrader: (4)

Yes, I misspoke and meant brake lights.