ABS amber light staying on '89 Reatta

[DS_Porter 89 Burgandy]

 The ABS light comes on and stays on steady after starting and never goes out. Checked for codes by shorting terminal A to terminal H according to the manual. No codes would flash and the light remained on steady. Th next step is to check the EBCM fuse which is located up under the driver side dash. Not an easy task for an old guy like myself who is not so

limber. I had to take the driver seat out.

  I found the fuse to be blown so naturally changed it and a new fuse also blew  (see page 5E1-58). So the next step is to get familiar with the EBCM - Electronic Brake Control Module - in the trunk. Disconnected the control cable and tried a new fuse. The new fuse did not blow and I had power on pin 2 as expected. The fuse blew when I reconnected the control

cable and turned on the ignition. Definitely a bad EBCM. With nothing to lose I opened up the EBCM and found a couple melted transistors. End of the road.

     So now begins a search for a replacement ECBM. I won't say "new" but perhaps unused would be nice. Any tips out there?   Thanx   Deano

[Dashmaster]

Deano, Welcome to the Forums. Looks like you did good work so far you ABS light issue.You should also check condition of all the ABS Sensor Leads for physical cracks and any breaks in the sheath . You can also test each from the truck with a meter and spinning the associated wheel. Bad wheel speed sensor will also set the ABS Light. So before buying the ECBM check these because if any are bad you will still have the ABS light on. Wheel Speed Sensors are hard to come by and usually cost $100 to $150 each.

You will then have the total cost for fixing the ABS. I know East Coast Reatta Parts had wheel sensors, they may also have the ECBM

Do you the the ABS is not needed to Drive the Car. Brakes work normally like any system without ABS. .

Wayne

Edited June 6, 2016 by Dashmaster (see edit history)

[DS_Porter 89 Burgandy]

Since I did not know why the original ECBM failed I decided to buy a used one on Ebay for just $60. I won't be out much if it fails due to an external problem. I first tried to check each wheel sensor and the book says that each sensor should read about 800 to 1400 ohms. I get no continuity (infinite) on any of them. I do not have the pinout tool so I checked separately the incoming leads and also the pins on the ECBN with the connector removed. No continuity anywhere. So I gave up and decided to plug in the replacement and see what happens. First I checked the fuse one more time by turning the key on with the connector unplugged. I had power on pin 2 as I should. I plugged in the replacement and started the car and after the pressure came up both the red and the amber lights went out as they should. All good. I will be looking for an opportunity to check the antilock on wet pavement but conditions don't always allow it.

[DS_Porter 89 Burgandy]

This is a used replacement ECBM and it may or may not have any history codes set and stored but yes it is a good idea regardless. Just out of curiosity I would like to see the code reading procedure work for me. Hopefully there is nothing current. If there was I assume the amber light would be lit. I'll get back to you.

Deano

[DS_Porter 89 Burgandy]

   Checked for trouble codes today on my used replacement EBCM. Everything went according to the book and sure enough it did have two codes stored as history. Code 21 - Main Valve  and Code 47 - Rear Wheel Sensor.  I ran the test three times and it repeated correctly. Then I drove it faster than 18 mph and the codes reset and did not return. All good. The final test will be wet pavement and a skid to be sure the petal pulses........    Just need a little rain in Seattle

[DAVES89]

I believe that when a sensor lead trips one always gets other codes, most commonly a main valve issue. It has been my experience that replacing the bad lead and clearing the code straightens everything up.

[Barney Eaton]

As a new Reatta owner and living in Seattle let me suggest you flush the brakes in the near future.

The 88-90 ABS system used on the Reatta has hydraulic boost....and they do not like dirty fluid, the brakes and boost system uses the same fluid and you live in a very humid area.  All this leads to moisture in the brake fluid which causes problems........flush out the old fluid

[Barney Eaton]

The thin coffee stirrer is a good idea.......I would offer this suggestion.....

When you turn on the key in about step 6..... I would not add fluid, I would suck out the fluid again, the reason....the system is depressurized, you turn on the key and it sucks clean fluid into the pump and accumulator.

I would then pump the pedal again (with the key off) this will empty the accumulator into the reservoir......suck that out as you did before, add fresh fluid and turn on the key (that step can be repeated until you feel the pump/accumulator has been flushed) when happy with the color of the  fluid then proceed to flush the brake lines. 

[DS_Porter 89 Burgandy]

Thanx fellas for your info and experience. I will gather the necessary stuff and get it done. No hurry.