2001 GMC Jimmy w/Intermittent ABS Light

[monk02]

I recently had brake work done to my vehicle (eg. rotors, pads, calipers, master cylinder) because the brake pedal would sink to the floor whenever approaching a stop sign. Before coming to a full stop (greater then 10mph), the brakes work normally. However, that didn't fix the problem. What fixed the problem ultimately was the replacement of the valve modulator on the ABS. What has now happened, every other day, the ABS and brake lights go on and stay on until the engine is turned off and then turned on again. The brakes seem to work fine......the shop told me that sometimes with the new modulators, the valves being new have some 'resistance' as it takes time, as they move back and forth to 'work them in'. Does this mean that there might rather be air trapped in the ABS modulator that needs bleeding again ? My understanding is that bleeding the brakes with ABS is a pain and that a person needs a system tool to do the job right.

[MT-2500]

They are feeding you a big bull line hook and sinker.
Better find another repair shop that knows what they are doing and know how to bleed the abs brakes with a abs capable scanner.
If the brake light comes on you have a problem.
First step is to get the abs code and post back code for help on it.
MT

[monk02]

I admit, the reason did sound flaky. The only other thing to replace would be the control module for the ABS and that's $929 IF there is no air in the system. But I doubt that is the problem......the ABS works just fine.

[MT-2500]

You need to catch the code when the light is on and go with what the code says.
Good luck
MT

[monk02]

What model system scanner to buy would be best for my 2001 GMC Jimmy ?

[MT-2500]

The GM tech 11-111 scanner or a snap on Solus scanner will do Air bags And ABS.
But the price range is 3500 -5000 $ USA dollars.
For a one time dealer it is best to pay a repair shop to scan it.

[blazes9395]

Like MT mentioned, get it scanned. If the lights both go on (ABS & BRAKE) and reset after, I am willing to bet its most likley a loose or shorting ABS line from one of the wheel sensors. If it was damaged during the brake job, or not routed properly after the brake job, it will cause a short and both lights will come on like that.

[duke350]

Actron also has a new ABS scanner. I know nothing about it, I just saw it sitting on the shelf at a local parts house. Its priced at about $300. I have no exp. with it, I just saw it there.

[GMC3peat]

Hello Folks, great forum!!...1st time user...for a novice I find info. 'bang on'...my 2001 Jimmy is having the same problem...either starts out with no lights & after a few minutes ABS & parking light come on..or...starts with ABS & parking light on...any inexpensive way to test & repair this??

[MT-2500]

Welcome to AF.
Read threw this thread and it explains how to test for a ABS light.

On your problem it is best to start a New Thread.
Saves on highjacking a old post that was started by someone else.
Hit the New Thread button and give all information and someone will help you.
MT

[GMC3peat]

still looking for that New Thread button...in the meanwhile...mechanic tells me it was a C0265 code that he cleared a few times & re-appears...

[MT-2500]

Originally Posted by GMC4peat

still looking for that New Thread button...in the meanwhile...mechanic tells me it was a C0265 code that he cleared a few times & re-appears...

Left side and up a little at the top of post.
MT

[MT-2500]

Code is for wiring circuit problem that can lead several directions.
This is a code where you need to go threw the repair flow chart for the code.
Does you mechanic have any repair information or what did he say to do on it?
Are you going to DIY it or let him fix it?
MT

[missyh2003]

I have been having the same issue with mine for a couple of years now. I was told that it was a sensor that was probably damaged by salt during the winter. I priced the sensor....and for about $900. bucks it can be replaced...Ha, Its gonna stay on for a while. I did find a website that sells them for about half of that, but I think since I am not having brake issues other than that, I will live with the lights on for now.

[old_master]

This is a very common problem and can usually be repaired by a DIYer in about an hour with a digital volt meter and basic tools.

Brakes - Low Speed (Below 5 MPH) ABS Activation

Bulletin No.: 02-05-25-006B

Date: January 05, 2006

TECHNICAL
Subject:
Antilock Brake System (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface) Models:
1999-2000 Cadillac Escalade
1995-1999 Chevrolet Silverado (Old Style)
1995-2000 Chevrolet Suburban, Tahoe (Old Style)
1995-2003 Chevrolet Astro Van, Blazer, S10
1995-1999 GMC Sierra (Old Style)
1995-2000 GMC Yukon, Yukon XL (Old Style)
1995-2001 GMC Envoy, Jimmy
1995-2003 GMC Safari Van, Sonoma
1995-2001 Oldsmobile Bravada

Supersede:

This bulletin is being revised to update the correction and warranty information. Please discard Corporate Bulletin Number 02-05-25-006A (Section 05 - Brakes).

Condition:

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

Cause:

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

Correction:

Measure AC voltage and clean wheel speed sensor mounting surfaces.

1. Raise the vehicle on a hoist.
2. Disconnect both the front wheel speed sensor harness connectors.
3. Place a DVM across the terminals of each sensor connector.
4. Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.
5. If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.
6. Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.
7. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, ScotchBrite(TM) or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
8. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
9. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (Canadian P/N 89022218).
10. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor 0-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037).
11. Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub.
12. Install the rotor, the caliper and the wheel.
13. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's.