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On my 90 the rear cylinders were leaking, so I replaced them and put on some new shoes, since the old ones were down to the rivits. Yes the truck ran out of brake fluid when one of the cylinders blew.

Then after I finished doing that I pulled off the calipers and found one of the calipers leaking around the piston. OKay, new reman calipers.

Filled it with brake fluid- bled the Pass Rear, Drivers Rear, RABS, Pass caliper, Driver caliper. The RABS bleeder would not bleed at all. Rear antilock light is on, so maybe that why it wouldn't bleed? I even pulled out the bleeder and pumped the brakes, no fluid came out.

Adjusted the rear drum brakes, the pedal and braking feels great. Pulled the rear tires off the ground adjusted the adjusters, and made sure the emergency brake was not sticking. Its releasing and that is not the cause of the red brake light.

I tried resetting the brake proportioning valve by cracking open one of the outlet lines on the master cylinder while I had someone slowly press down the brake pedal- The brake light never went out. I tried the other outlet line that runs directly to the RABS on the frame. The light did not go out. I only cracked the line enough for the brake fluid to roll out. I didn't pull off the line, in fear of allowing air into my freshly bleeded brakes.


So why is the red brake light not going off?
 

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I jacked up the rear of the truck and put it in drive. To completely stop the wheels the brake pedal must be pushed almost down all the way. That doesn't seem correct... Both wheels are stopping at about the same amount of pressure on the brake pedal. So I presume both wheel cylinders are working correctly. I couldn't get someone to stand behind the truck to make sure both wheels were stopping at the same time. But from me sitting at each seat and pressing the brake pedal, they seemed to stop at the same time.

The red brake light is still blazing away, and I don't know what to do from here.
 

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The very first thing since you've messed with a few things is disconnect your battery. Let everything reset (leave it disconnected for a few) and then reconnect and drive it to see if it comes back. I can't tell you after screwing around with stuff how many lights I've gotten rid of that way. If that doesn't work post back.
 

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I'm not up on 4 wheel ABS, ('89s are rear only) but I would try to run diagnostics on it if Audra's tip about the battery doesnt work.

Double check your e-brake.

I didnt think the RABS module needed bled if the ignition was off during the repairs. Didnt on my '89. I would also check Steve's stuff. He has a butt-load of diagrams on the ABS function.

Good luck. I fixed my '89 during the frame-off and finally got the light off. It took a couple of controllers and some small parts, but it was easy to diagnose and fix.
 

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Check Steve83's supermotors for the diagram and procedure on pulling codes from the 4wABS system.
 

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Discussion Starter #7
I'm not up on 4 wheel ABS, ('89s are rear only) but I would try to run diagnostics on it if Audra's tip about the battery doesnt work.
4 wheel abs is 93-96 broncos. Mine is a 90, which has RABS, just like your 89. ;)

Double check your e-brake.
Nope, e-brake is not sticking.

I didnt think the RABS module needed bled if the ignition was off during the repairs. Didnt on my '89. I would also check Steve's stuff. He has a butt-load of diagrams on the ABS function.
I wasn't sure either. I think it didn't bleed since the RABS is throwing a code, and might be closing off that section of the valve where the bleeder is. But, I don't think the RABS will throw a brake light. (just guessing, don't hold it against me if I'm wrong.)

I've also read steve brake/hub section over 10 times.

Good luck. I fixed my '89 during the frame-off and finally got the light off. It took a couple of controllers and some small parts, but it was easy to diagnose and fix.
Ok, what did you have to fix?

Check Steve83's supermotors for the diagram and procedure on pulling codes from the 4wABS system.
No thanks. :toothless

Common you know better than that.

90=RABS
 

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Discussion Starter #8
The very first thing since you've messed with a few things is disconnect your battery. Let everything reset (leave it disconnected for a few) and then reconnect and drive it to see if it comes back. I can't tell you after screwing around with stuff how many lights I've gotten rid of that way. If that doesn't work post back.
Deep down something tells me there has to be a better way. Ill hold off on that till last resort. But thanks for the help audra. :thumbup
 

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The 90 service manual gives a routine to pull RABS codes. When the light comes on, don't turn the truck off before reading the codes. Put it in park, chock both front & rear of the wheels, note whether the red brake light is lit also, then momentarily ground the test connector.

The test connector comes out of a large loom under the dash, coming through the firewall, near the parking brake. On mine there are 2 similar connectors in that area, the correct one has only 1 black wire with an orange tracer running to it, & was hidden on top of the loom. The correct one is hanging down on the bottom right of the pic below.

After you've grounded & ungrounded the wire, the yellow abs light starts to flash. Count the flashes. It said to not count the 1st series, because it may start in the middle. The last flash of the series is a long flash. Then it repeats over & over, until you turn the key off.

Count all of the short flashes & the long one together (So 4 short & 1 long is code #5). If I remember right, it should be a number between 2 & 15 or so. If you follow Steve83's sig link, & then go to his Brakes & Hubs album, he has the code definitions for RABS.

There are also more testing instructions in the manual that I can look up after you know what the code is, & whether the red brake light is on or off.

 

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I didnt see if you indicated.....was the brake light on before you started all the repairs?

Anyway, this is from memory......:doh0715: and it only applies to getting the RABS light out. I dont think it ever had the red(?) brake light on.



While I was collecting NOS pieces, I found a new solenoid, so as I was reassembling the chassis, I put it on. I think it was bad from previous tests.

When I started pulling codes, it indicated a circuit in the original "brain" was faulty. I substututed another one I had when I bought a used dash. It threw a different code. I finally broke out an NOS brain I found. That cleared up most of the codes. Then it threw the code for the speed sensor. It turned out to be a poorly connected wire. No codes.

Did you bleed the RABS solenoid with the ignition on?

Something else I am not sure about, on my '89, the cruise control for the brake (cancel) was from an electrical switch. At some point it went to a switch on the master cylinder.


EDIT: I re-read your first post. If you ran the fluid out it probably sensed a catostrophic failure and shut off the rear brakes. The early Broncos do that. My money is on the controller kicking in and needs "reset". Especially since the light is on. I am not sure how you do that, but my guess is that it has to be done with the ignition on. I can see if there is something in my Ford manual - absent someone chimming in.
 

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Thanks for posting this, the picture helped me understand.


The 90 service manual gives a routine to pull RABS codes. When the light comes on, don't turn the truck off before reading the codes. Put it in park, chock both front & rear of the wheels, note whether the red brake light is lit also, then momentarily ground the test connector.

The test connector comes out of a large loom under the dash, coming through the firewall, near the parking brake. On mine there are 2 similar connectors in that area, the correct one has only 1 black wire with an orange tracer running to it, & was hidden on top of the loom. The correct one is hanging down on the bottom right of the pic below.

After you've grounded & ungrounded the wire, the yellow abs light starts to flash. Count the flashes. It said to not count the 1st series, because it may start in the middle. The last flash of the series is a long flash. Then it repeats over & over, until you turn the key off.

Count all of the short flashes & the long one together (So 4 short & 1 long is code #5). If I remember right, it should be a number between 2 & 15 or so. If you follow Steve83's sig link tires, & then go to his Brakes & Hubs album, he has the code definitions for RABS.

There are also more testing instructions in the manual that I can look up after you know what the code is, & whether the red brake light is on or off.

 
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