When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A few months back I reinstalled my power steering computer, and at the same time I did that my brake lights stopped working. I recall that the connector came off the switch and I had to plug it back in, but otherwise I'm not sure what would cause that.
So in diagnosis I started with the basics. The fuse is tested good (with a multimeter), there is power at the fusebox, the switch has continuity when the brake is depressed and none when it isn't, etc.
However, there's no power at the two-pin connector for the brake lights. One would expect one side to be hot and the other to go to the brake lamps, but neither side is hot in my case.
I thought there may be a break in the wiring harness, so I traced the yellow wire on the connector over to another long white connector by the fusebox (presumably for the cruise-control option). It has continuity to there. So this makes it unlikely that it is broken in the harness. I have not yet traced the other wire but that is due to the next problem.
My brake switch wiring doesn't match what others indicate online, nor the FSM (sort of). I've found a few threads online where people indicate there should be a white/green and green/white wire going to the two-pin brake switch connector. I have a yellow wire and a black wire with a stripe (white or yellow, hard to tell). This diagram from the FSM shows what I mean:
Fairly straightforward. Battery constant > One side of switch > other side to CPU and to rear lamps.
Since that doesn't match what I had, I found that the yellow wire I do have goes to that connector for the cruise control. So when I look at the diagram for that, I get this:
So this one indicates two stop-lamp switches? One like mine with yellow/black wires, one with the white/green green/white wires. This also indicates two identical connectors. Which would imply to me that there is another two-pin connector someplace that I mixed up with the current one when I was reinstalling the PS computer. Thing is, I don't see one anywhere. And my brake lights were of course working fine before this.
To add to the confusion:
- My car has had features added / removed before. It did not come from the factory with PS or AC but both are present. I would not be surprised to find the CC was removed at some point, although there are zero CC parts on the car so this is unlikely.
- My car is an early '86 model (Oct 1985 actually) and I've noticed a few minor differences between the FSM and the actual car. Not many, but there is a bit of weirdness going on.
Ultimately I could easily bypass the factory wiring, but I'd rather do this right and fix it.
So any help is appreciated. I'm going to contort myself back under the dash as soon as I have some time and look again, but I took a really good look and did not see a connector with green/white & white/green wires anywhere under there.
i couldn't find a picture of it, but the brake switch with cruise control is one switch with two connectors. this one time i mixed up the clutch, cruise and brake lights, which was pretty funny
the other thing is that the harness should have the cruise control wiring in it (probably)
and third if you can find one the 1986 wiring colors are different, diagram is the same
i couldn't find a picture of it, but the brake switch with cruise control is one switch with two connectors. this one time i mixed up the clutch, cruise and brake lights, which was pretty funny
the other thing is that the harness should have the cruise control wiring in it (probably)
and third if you can find one the 1986 wiring colors are different, diagram is the same
My brake switch has one connector, so that makes sense. I tested to see if I mixed up the clutch switch and brake switch, but I didn't. Which makes sense since I never touched the clutch switch during the process.
The CC wiring is present. Although Mazda does call my model "low grade" in the FSM, which is why there was no rear wiper wiring and I had to make my own harness. There are other differences noted in the FSM where there is no wiring present for some features, I think mostly AAS related.
Yeah, the FSMs frequently found online are for the 1988 year. I'm not sure why they decided to change the wire colours. They also didn't change ALL the wire colours, just enough of them to make diagnosis frustrating
Thanks for the info, I guess I need to hunt for that other connector. Although I can't imagine where it went (since the brakes worked fine up until I put the PS computer back).
03-11-22, 07:37 AM
