I have been on and off again looking at why my ABS doesn't work on my 1986 Coupe. A few days ago I was under the car for other reasons when I noticed the way the brake lines looked. It is hard to see here but there is one line that appears to be blocked with a rotten rubber hose on it.

This can't be right.



http://www.flickr.com/photos/billcolclough/7990505008/

 

As far as I've seen on my 87 the only flex lines are going to the wheels. It may be some sort of vibration dampener.
Have you went through the diagnostic tree in the FSM?
1st off does the pump run right after the car moves? System selftest is done when the car makes 3mph the 1st time. If something is wrong it truns on the ABS light.
I've fixed dirty wheel sensors and a bad relay.

JS

 

Not the flex line, but what appears to be a broken or cut solid line that may have been plugged.

All electrical functions test fine. It was the one line that really had me wondering. I have since read that it my be a 1/4" return line.

 

The picture link didn't work for me.

If you're talking about this rubber coupling:



That's the line that connects the fuel tank to the vapor canister.

 

Thanks!

 

The reason your ABS does not work is that the front brakes are inefficient.

On my 86, the only way the ABS works was when I replaced the front brakes with C5 brakes,

now the rear brakes actually have a chance to really stop turning on a hard stop.
When the car slows faster, the rears get close to the ABS threshold, and the ABS cycles.

 

My ABS light comes on after the vehicle moves. I don't think that adding C5 brakes will correct it. I need to test each sensor but haven't had time to do that part yet.

 

you left out an important detail. (light) sucked me right in on that one.

check each sensor for ohms, 900-1500 is acceptable
Also, if it never worked thw whole time you had the car, make sure the previous owner did not put bearings on the car that did not have toothed hubs for the sensors to measure.

 

Good point. I never thought that someone may have put the wrong hubs on...assuming that is possible even with the wheels sensors connected.

 

Bad bearings will also throw the sensor alignment off enough to actually knock the tip off the sensor. If the sensor tip has a tip like a blade screw driver, its ok. If not, its damaged and thats the problem.

 

The sensors are magnetic and will collect iron filings from brake dust.
I'd start with a cleaning, inspection and ohm test as coupeguy suggested.

You can also find a wet roadway and attempt a panic stop to activate the ABS.
I hose down the street in front of my house for this purpose. 30 MPH is enough.

 

The ABS will kick in at VERY low speeds. Mine did this afternoon when I made a quick left turn into my driveway in front of a truck and a lot of traffic I didn't want to wait for. I was only going about 5 MPH and the tires hit the dirt and trash along the side of the street.

The supply of new sensors has dried up. You'll have to go used if you need a new one. Make REALLY SURE you get the entire sensor harness. The ones I bought were cut off about 12" from the sensor. I REALLY wanted those missing connectors. There was a design change in 1988, so you need the earlier sensors.

 

When the car starts up the ABS light does its test then goes off. When the car gets up to the test speed that is when the ABS light comes on. I have tested the relays, I can hear the pump doing its test when the car starts.

Tonight I cleaned the front wheel sensors. The right side had alot of grease on it. The teeth seemed to have lots of grease as well...is that normal?

This weekend I will find the time to check the rear sensors and ohm test them all. I am tired of looking at the ABS light!

 

The sensors should be clean and dry.
Grease? Wheel bearing seal going bad?

 

There seems to be a lot of grease on the teeth of the drivers side bearing. I have had the car for 10 years and I haven't had the bearings replaced (I have been taking my time with the ABS

The ABS light only started working a few years ago...when I took the dash apart and noticed that there wasn't a bulb in that socket.

Looks like I will do the bearing soon just to be safe.

 

Trying to figure out why the ABS on my 1986 coupe is it working. Just had brakes redone by local shop: new rotors, hoses, hub bearings, calipers, pads , master cylinder and (1) rear abs sensor. When starting to drive ABS clearly does self test- I can feel it in the pedal and it's extremely hard to press on the pedal- then the system realizes the ABS isn't working, the ABS light comes on and my regular brakes work just fine. I was convinced it was the relay to the control module so I took it out and cleaned the contacts and also cleaned the contacts on the connector to the control module. Then, when driving, I could hear the pump constantly turning on and off, and sometimes the brakes worked like without the ABS and sometimes the pedal would be hard to press down. Finally the ABS light came on and regular brakes worked fine without ABS. I did find a relay from someone on one of the forums and he swore he tested it. However when I swapped it in the ABS light immediately came on and my brakes worked fine but no ABS test occurred when starting to drive. So I'm thinking that my original relay is OK . I did notice there was a connector not attached to anything with a green and white wire and what looks like some sort of resistor or diode attached between the ends of the wire at the connector with tape covering the end (clearly rigged). I have no idea what this is or if it should be connected to something. At this point I'm thinking the problem is either the control module or the wheel sensors... Does anyone have any ideas?