"BRAKE" and brake wear indicatiors on full-time

[MrT]

The manual says this is the brake wear sensors worn through to open the circuit, but I can short circuit the sensor connectors (bypassing the sensors) and nothing changes. Car is a '93L driven by my son. Brake pads are in good shape and we fixed broken sensor connector wiring fully expecting the lights to go out when we did so. Didn't happen.

Also, we found the brake sensor connectors (big nylon cylindrical connectors on the fenders under the hood) to be crumbling. I see how to replace the outboard side running down to the calipers, but is there an easy way to replace the harness side connector? I have a parts car to rob those connectors from, or I _could_ simply use bullet connectors from the parts house if I want to be able to measure the sensor resistance without pulling the wheels. OK. I'll do that. Great idea. Thanks. Gee, you guys are smart. Now if you can only be that helpful about Q#1 above.

MIchael

[Alfisto Steve]

Quote:

Originally Posted by MrT The manual says this is the brake wear sensors worn through to open the circuit, but I can short circuit the sensor connectors (bypassing the sensors) and nothing changes. Car is a '93L driven by my son. Brake pads are in good shape and we fixed broken sensor connector wiring fully expecting the lights to go out when we did so. Didn't happen. Also, we found the brake sensor connectors (big nylon cylindrical connectors on the fenders under the hood) to be crumbling. I see how to replace the outboard side running down to the calipers, but is there an easy way to replace the harness side connector? I have a parts car to rob those connectors from, or I _could_ simply use bullet connectors from the parts house if I want to be able to measure the sensor resistance without pulling the wheels. OK. I'll do that. Great idea. Thanks. Gee, you guys are smart. Now if you can only be that helpful about Q#1 above. MIchael

[MrT]

Quote:

Originally Posted by Alfisto Steve Connectors inside engine compartment aren't they for air bag and ABS?

[Alfisto Steve]

Quote:

Originally Posted by MrT Now, Steve, you know? You might just be right. I'd thought I'd traced these wires before, but I may have really mis-remembered. I'd "confirmed" this in my memory when I saw the wires snaking down to the wheel well, but I'd forgotten about the ABS sensors. Oh, well. That's what happens when you don't get the manual out. I still have to bypass the sensors down behind the wheels now. Maybe that's where the mystery lies. If so, then you'll have been once again a wealth of wisdom. Michael

[MrT]

The funny thing is that all of the lights work, tail and front. The problem is that too many lights are lit.... Two red ones on the dash stay lit: the one labeled "brake" and the one with the circle that looks like a brake disc. Like I mentioned above, but didn't explain quite as explicitly as here, the only problem is that these don't go out. The manual says the "brake" one is for low brake fluid and that if the pair go red only when brake pedal is pressed, it's indicating contact of the brake sensor against disc. If they stay red all the time, then the brake wear sensor wire is worn through and gives open indication between the two pins. But I mustrusted my memory and have to look again about the brake wear sensor pins.

Michael

[nocemarco]

Replace the switch infront of the brake pedal...its most likely that, I had the same problem.

[AlexGS]

The wear light has two functional modes:
1. When the wire loop is earthed, warning light comes on. This is intended to occur when the pad contacts the disc and the pad has worn down to the wire loop.

2. When the wire loop is worn through (becomes open-circuit), the warning light comes on. This is intended to occur when the pad has worn down a long way.

Now on my previous 164, I had the same symptoms that you're having and it was because the pad warning light wires (two of) were chafed on the caliper/brake disc, etc. If the wire becomes 'earthed', then the light stays on. If the wire gets chafed right through, then the light stays on...

For some of the more recent Italian models (probaby not the 164), the pad 'loop' is replaced by a single wire. At the plug connector, the plug has a wire loop so that the circuit is always complete. Then, the light comes on only when the wire is earthed. Still the same problem of course - if the insulation gets chafed through, the light comes on.

The solution is to get some 'spaghetti tubing' (woven fibreglass insulation sold in electrical shops, as used in ovens/heaters). Cut the plug off (or remove terminals etc.) and thread the insulation over the wires. A bit of insulation tape WON'T do...

I'm not saying the other suggestions in this thread are not valid, just reporting on what caused the problem on my 164

By the way I think my 164 had the ABS-style connectors inside the wheelarch for the pad wear wires, but this varies from year to year. The real ABS connectors are on top of the suspension struts, in the engine bay.

-Alex

[twoliterlover]

My 164 repair books book ssuggests that you have the wrong size tail light bulbs which allows the current to cross flow back around through brake light and worn brake light sensors. This is NOT a joke. Do you have the right size brake light and tail light bulbs in the rear? Did you replace them with similar looking American ones?

[MrT]

This is _possible_, I guess. The car was being handled by my daughter when the problem showed up quite some time ago. The lights all illuminate properly, but I'll look at the lamp type now that you've mentioned it. Thanks for the off-normal suggestion.

Michael