CurtP

Has anyone bypassed the brake pad wear sensor on the instrument cluster? The wires are no longer in the loom for the rear sensors, so it will need to be bypassed on the gauge cluster itself. Fronts will get the same treatment when I rebuild that loom at a later date, so if I can bypass them both now, that would be great.

The bulb for the wear sensors has already been pulled, but that doesn't extinguish the "!" light. I'd prefer not to have to pull the bulb to that indicator if possible.

Speaking of the "!" light, other than the wear pad sensors (deleted), airbag system (deleted) and low oil light (deleted), what else does it indicate, other than when the emergency brake is on? If it's only for the emergency brake, maybe I'll pull the "!" bulb after all.

billthe3

The ! light is also the emergency light for loss of oil pressure, low oil level, stuff like that. I'd leave it in IMHO. Let me look at some wiring diagrams to figure out if there is a fuse or something you can pull for the brake sensors.

Bri Bro

To bypass the brake pad wear sensors jumper pins 6 and 7 of Plug A of the instrument cluster.

ibkevin

Excellent, thanks Brian, that system really was over kill.

Bri Bro

It is one big loop, all the wear sensors are connected in series. I have to do this myself so if you beat me too it, post some pictures.

billthe3

Yeah, thanks for that info. I may do this myself since mine apparently have a short somewhere in the circuit because the light has come on when it shouldn't have.

Bri Bro

More then likely you have an open rather then a short. Check that all the connectors are OK and the wear sensors haven't opened.

CurtP

Thanks! Hopefully that will do it for me. I'm using a '86 harness in my '87 and when I unwrapped the harness, I pulled out the wires for the brake sensors. One went to the gauge cluster, and the other one went to the fuse panel.

So if I understand this correctly, the logic is built into the gauge cluster. I have a spare cluster that I'll take a look at today to see if I can trace it to the logic board.

Bri Bro

I can get you started. On the 12 pin connector that is called "additional electronic in Instrument cluster", the brake pad wear indicators come in on pins 1 and 2. The brake pad wear light connects to pin 7.

The central warning light uses a bunch of diodes connected in what is called a diode "OR". If any one of several faults occur (signal goes low), a diode path is opened up to the indicator light tuning it on. Very simple circuit.

CurtP

What a day! I did a temporary jump between pins 6 and 7 (my pin 6 was empty) and I still had the "!" light. My car is an '87, the gauge cluster that came out of my car is from a '85.5 - '86 (something the PO did) and the cluster I wanted to use was out of an '89. I was having some weird issues with the later cluster too - occasionally it wouldn't work at all. So out of curiosity, I popped in my '86 cluster, no "!" and the brake pad wear indicator was extinguished. So it appears that the logic boards aren't compatible. The gauges can be transferred though, which is what I did.

Something I thought was interesting - the odometer on the '89 cluster is made completely different. I suspect to correct the broken odo gear issue. I finally have a gauge cluster that all the faces match well and I got rid of the factory boost gauge - I didn't think it was needed since I have a boost gauge on the A pillar.

Bri Bro

Pulled my dash out and I found a white "A", "B" and "C" written on the three connectors. Plug A is on the left side as you are looking at the cluster. I went to the prints and it said the wire colors going to the plug A are:

Pin 6= BR/WS (brown with white strip)
Pin 7= BR/RT (brown with red strip)
I didn't see pin number on the connector so I needed the wire color of pin 1 =Blue.

I stripped back the insulation on the wires about two inches back and shorted them together with a small bare wire, added some solder and taped them up.

Put the plugs back on, started the car and NO BRAKE PAD WARNING LIGHTS!!

CurtP

I have the same markings on my connectors. I had no pin 6 because that was one of the wires I pulled out of the harness. There are pin numbers on the plug - if you look at the face of the plug (where the opening is that plugs into the cluster), right above each connector is a number. They're really small and hard to see (I can actually see them on your 1st picture though).

Since I didn't have a pin 6, I just pulled one out of my original harness, cut the pigtail to about 1.5", pulled pin 7 and soldered it to the edge of the crimp, then put it all back together. I could have just pulled the bulb and been fine though - it seems that on this cluster, the brake pad wear indicator does not illuminate the "!" lamp.

I still have two other electrical problems that I have to trace down though - the passenger side mirror goes up and out, but not down and in. And the sunroof goes down, but not up.

reno808

nice I will be doing the same after it warms up a bit