Jinark

Hi Folks. I'm new here, just joined. I hope to learn a lot from the seasoned veterans and may be able to contribute something myself. Right now I'm looking for a solution to a RABS problem. I've searched the archives and haven't been able to find anything that helps me.

Last year I bought a used 1997 F150 XL v6, 5 speed regular cab, long bed, essentially a work truck with 100,000 miles on it. Everything functions normally except the brake warning light stays on and the ABS light is on. The truck brakes normally. When I bought the truck I bled the brakes until the fluid ran clean at each wheel. I've bled brakes for years so I'm positive I did it right. No joy, the lights stayed on. I replaced the ABS part that mounts on the top of the diff, again no joy, the lights stayed on. So, I ignored the problem since the truck seems to brake OK and we only use it to make runs for house renovation supplies, to the dump, pickup landscaping supplies and the like. We've driven it less than 2,000 miles in the past 14 months. But, I'd like everything to work if it isn't going to cost and arm and a leg .

Today I decided to look at the problem again. If I disconnect the three wire plug from the brake fluid reservoir the brake light in the IP goes out, but the ABS light stays on. Engage the emergency brake and it comes on; release the emergency brake and it goes out. This tells me the E-brake switch is OK. Also if I start the engine with the plug not plugged into the reservoir switch the ABS light goes out for about half a second and then comes back on and stays on.

So, what's the consensus on my next step? What should I do next? right now I'm driving it with the reservoir plug discoinnected so I don't have to look at a glowing brake light on the IP.

RLXXI

If your certain you only have RABS and not 4WABS one obvious problem is the fluid level sensor in the master cylinder reservoir, the other problem is most likely the rear wheel speed sensor but before you go spending any $$ on parts, follow my guidance in another post here with a similar issue starting with post #14.

If you pull a different code than that guy, post back here and I'll guide you through the t-shooting steps.


https://www.f150forum.com/f10/96-2wd...2/#post2461586


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Jinark

Thanks, I'll check the other thread. I did replace the rear sensor and I'm positive I have ABS.

RLXXI

Yes but there are two different systems, one is all 4 wheels the other is rear wheel only.


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Jinark

Whoops, typo on my part. I meant to say I have RABS.

Anyway, as per your other post I pulled the code. three shorts and 1 long, so code 4. Where is this plug my mentioned in the other post you cited? I crawled under the truck and looked along the frame on the driver's side and found nothing. Apparently I'm looking in the wrong place.

RLXXI

On your year model it's mounted directly under the master cylinder, on the brake booster. The diag for your truck is also a little different.

I'm getting ready to fire up the grill so it'll be a little bit before I can guide you.

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Jinark

Got it. Oval plug with 4 wires.

Grilling is more important. I'm in no hurry at all. When you get the time let me know what to check. By the way, in case I forget it later,.......Thanks.

RLXXI

Ok are you adept with a dvom? Because if not there's no sense going any further.

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Jinark

I've got 2 or 3 digital multimeters around here. So, yes I know the basic functions.

RLXXI

Good deal, you already found one fault, the fluid level sensor, now we can move forward with diagnostics.

I'm 95% certain the RABS valve is bad but there are a few tests to make sure.

What is the build date of your truck, should be on a sticker on the drivers door or door jamb.