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Discussion Starter · #1 ·
Hi

The wife fire up the bronco today and the brake and ABS light came on at the first stop sign.

Bronco is a 92, E4OD, 351, PS, ABS with 186,000 KMs

Any ideas what may cause this to happen when the truck seems to function OK.???????????

Thanks
Doug
 
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My '90 bronco has the "rear-ABS" light come on all the time. I haven't worried much about it yet. But in the winter I will deffently want ABS. It sounds like we have much the same problem.
 

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I just replaced a brake line and hose on my 90 because it rusted out. And when I got done both lights were still on. My fluid was full , I bled the rear brake good. but I forgot to bleed the proportioning valve also. It had air in it . If your fluid is low, that might be it. Or maybe it is bad? I just have RABS. something is causing the abs light to come on.
 

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Re: 92 Bronco with brake and ABS light on?

Check your owner's manual.
The brake light means the park brake isn't fully released or the fluid is low, and the ABS light (all '87-92 Broncos only have RABS; 4WABS started in '93) means it isn't working for whatever reason. A Haynes manual will show you how to pull the codes from the RABS-II computer, but it usually means the sensor in the rear differential has become fouled with metal shavings - pull it out & clean it off.
 

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Re: 92 Bronco with brake and ABS light on?

There are certain faults that will set the antilock light AND the brake light.If the antilock valve on the frame rail fails it will set both lights on.

Billy
 
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Re: 92 Bronco with brake and ABS light on?

"all '87-92 Broncos only have RABS; 4WABS started in '93"

How difficult (if at all possible) would an upgrade to 4WABS be? Is it as simple as finding a 93+ bronco and swaping some of the front axel/stearing/brake components or would it require custom fabricated stuff?
 

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Upgrade

...uuuuuuuhhh... I'll give you a COMPLETE list when I'm finished with mine!
So far, I've collected/installed:

'96 Bronco front axle (all you really need are knuckles, spindles, hubs, tone rings, & sensors)
3-channel 4WABS pump assembly
3-channel 4WABS brake lines (you can reuse ANY rear line from the trans crossmember back)
'87 rear axle ('87-current with ABS sensor on top of the diff)
'96 Bronco 4WABS wiring harness (it's integral to the '93-96 Bronco engine compartment harness, so you have to completely swap harnesses or do some butchering)
3-channel 4WABS computer from '98?? Explorer (of course a Bronco computer would be easiest, but I'm gonna try for Traction Control
)
'93 master cylinder & reservoir (probably any '87-97 MC would be OK)

I think I have everything now, but I haven't installed the harness/computer/lines, so I can't tell you for sure.
 

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Re: Upgrade

you also need a couple relays, the accelerometer, and possibly a PSOM for signal conversion. it's not impossible but it will have some custom work and could get confusing if you dont label everything very well. good luck
 

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Re: follow up on RABS light

This'll be much easier if it's in the same thread...

In reply to:

Today I went out and pulled the diagnostic code from the RABS1 computer in my bronco. I read 9 blinks, which my haynes book tells me is a "Open speed sensor or Harness". So I might have to replace the speed sensor instead of just cleaning the metal shavings off. Once I have a methoid of rasing the truck I can figure more out.

Another thing I am wondering about is this: The haynes manule says "The diagnostic connector has two mating halves. . . disconnect the two halves." Mine doesn't have the two halves. I only have the one half with the black/orange wire in it (male connector inside a plastic boot). I looked for the other half of the connector but the only thing I could find was a black/green wire (with a female connector) which was pluged into the parking brake.

So could my lack of a matching connector for my black/orange wire be part of my problem?
Did you read Ch9-Sec14.2: "RABS II module part numbers begin with F3TF-2CO18 or F3UF-2CO18; all other RABS modules should be considered RABS I."

Have you looked at illustration 9-14.20b? If you have RABS I, that BK/O wire should have been connected to a R (red) wire with a matching connector. The red wire is the KAPwr wire. Did you read the Note at the end of 9-14.1, just before Pre-Check? "Some problems such as those associated with brake fluid level or loss of power to the module will cause the system to be deactivated and the YELLOW ABS light to be illuminated, but will not provide a diagnostic flashout code."

How about the note at the end of the Pre-Check (end of 9-14.8)? "A blinking yellow ABS light indicates loss of Keep Alive Memory power (RABS II only)."

Why do you need to raise the truck? There should be plenty of room to crawl under or roll on a creeper to get to the rear axle from the front side. From there, you can trace the wire that's clipped to the e-brake cable to see where it's broken or shorted. That code doesn't necessarily mean the sensor is bad - you should look for an "Open harness" before assuming you have an "Open sensor".

BTW If a new sensor is more than $30, consider a used one...
 
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Re: follow up on RABS light

In reply to:

Did you read Ch9-Sec14.2: "RABS II module part numbers begin with F3TF-2CO18 or F3UF-2CO18; all other RABS modules should be considered RABS I."

Have you looked at illustration 9-14.20b? If you have RABS I, that BK/O wire should have been connected to a R (red) wire with a matching connector. The red wire is the KAPwr wire. Did you read the Note at the end of 9-14.1, just before Pre-Check? "Some problems such as those associated with brake fluid level or loss of power to the module will cause the system to be deactivated and the YELLOW ABS light to be illuminated, but will not provide a diagnostic flashout code."

How about the note at the end of the Pre-Check (end of 9-14.8)? "A blinking yellow ABS light indicates loss of Keep Alive Memory power (RABS II only)."

Why do you need to raise the truck? There should be plenty of room to crawl under or roll on a creeper to get to the rear axle from the front side. From there, you can trace the wire that's clipped to the e-brake cable to see where it's broken or shorted. That code doesn't necessarily mean the sensor is bad - you should look for an "Open harness" before assuming you have an "Open sensor".

BTW If a new sensor is more than $30, consider a used one...
Okay I deleated my post. I didn't want to hijack this thread, but whatever.

I'll try to answer the questions you asked. I deffently have a RABS I module. So I was ignoring all RABS II info in the haynes book. I thought fig. 14.20b was for RABS II but I guess it's for both. I see (in the book) where my BK/O wire should connect to a R wire. I'll check agian in the morring if I can find the red wire. I wish I had a digital camera so I could show you what I'm seeing.

As for raising the truck, I don't have a creeper (or hardly any tools at all). I'll try crawling under to check the harness & sensor.

Thanks for your help (and your patience putting up with my uneducated questions).
 

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O/T - Hijack?

This is your thread about your brakes - you're not hijacking it by continuing to use it. And having all the posts on the same page makes it much easier for anyone to follow or review what's been said & done. As long as you're still working on the subject of the original post in any thread, I'd say keep using that thread. JMO
 
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Update on RABS

Okay here is a big update. I got under the bronco and found the RABS sensor. I unfasened the sensor from the rear diff and pulled it out. I tested the harness and both wires tested fine (0.20 ohms). I tested the sensor and my meter couldn't get a reading (infinate ohms). So I am all but sure, it's the sensor which is the problem.

What should a "good" sensor look like? mine has the long rubber cylender which goes in the diff. At the boddom of the cylender mine has a little metal square sticking out less then a milimeter. It almost looks like the metal square is what is left from somthing braking off?

I'll try taking a picture of my sensor. I should be barrowing a digital camera tomarrow.
 
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more info

I forgot this stuff:

I looked everywhere under the dash tring to find the red wire to plug my BK/O wire to. I could not find this red wire. Could somebody else who has RABS I look and see where this red wire comes from/goes to?

In the diagram the red wire comes from the fusebox. The fusebox has a huge bundle of wires coming from it. Should my red wire come out of this bundle?

Steve, you said I should look into buying a used sensor. Where should I try to find a used sensor? A junk yard? I don't think there are any junkyards around here. I assume if I go to the ford dealer they will only be able to get me a brand new sensor.
 

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Re: more info

The wink at the end of that post meant that I have a BUNCH of used parts, INCLUDING an ABS sensor or two.
The big trick is FINDING any given part in the HUGE pile...


If the sensor reads open, then I agree that it's bad. No, nothing broke off - it's a Hall-effect sensor, much like the head of a tape player. That's what it's supposed to look like.

Yes, the red wire should be in the harness at the fuse block, but you should be able to find the matching connector dangling somewhere near the BK/O. Ford switches colors every now & then, so don't restrict yourself to red.
 
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Re: 92 Bronco with brake and ABS light on?????????

I had an 87 Bronco with the same problem. I found out that it was the proportioning valve. These parts are in such a spot that they will rust away and cause problems without showing up on codes. It is however more that $100 from Ford.
 
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Re: more info

I finaly had some free time and I picked up a new ABS sensor. Sorry steve a new one was only $10. The new sensor cleared the ABS problem up right away. Thanks for your help.

I still haven't found the plug that is suppost to plug into my BK/O Diag wire. Here are a few pictures I took of my wire bundel. Excuse the quality, the camera wouldn't show anything in the viewfinder because it was so dark.


 
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