Brake/ABS light stays on, no apparent problem 2001 Astro

dhspring · 08-11-2009, 07:29 AM

I've seen several issues related to the brake and ABS light coming on the Astro vans. I have a 2001 with 119000 miles and this just occurred on mine. My brake fluid was a bit low which I thought was the problem, but after filling, the light still comes on. Also it is not constant, sometimes after shutting down overnight, the light is off and stays off for a while, then it will come back on, I'd assume after hard braking or whatever, maybe a bump in the road. I see no leakage of brake fluid on any of the wheels. After filling the fluid reservoir the level stays topped off, so I don't appear to be losing any fluid. I'm thinking it's a bad sensor.

Since this model has drum brakes on the rear, I am thinking that there are only 2 sensors for the ABS, one on each front disc brake, is that correct? I don't think the drum brakes are antilock capable.

Also, will a defective ABS sensor cause any safety issues? I don't think they can cause the brakes to lock up can they?

Lastly, can the diagnostic computers at Autozone they let you use for free troubleshoot this problem?

Any advice is greatly appreciated, thanks!

dhspring

Blue Bowtie · 08-11-2009, 08:54 PM

You need an ABS-capable scanner. The free scans provided by many auto parts stores do not normally test ABS and SIR systems.

dhspring · 08-12-2009, 07:46 AM

Thanks Blue, will do. First I will pull all wheels and see if there is anything suspicious before going to the shop, maybe it's a loose wire or leaking wheel cylinder, although there is no evidence yet of that. If I find out on my own, I will post the cause of the malfunction.

Blue Bowtie · 08-21-2009, 11:54 PM

Does only the amber ABS warning light turn on, or does the red BRAKE warning lamp also turn on?

If both lamps turn on, it may be an ABS power or controller problem. If only the ABS lamp turns on, it may be a sensor (the RW sensor on an AWD is on the transfer case).

dhspring · 08-31-2009, 06:51 PM

Both the red brake and the ABS lights are on when this occurs, but it is intermittent, sometimes it's on, then other times it's not. I'm not going to worry about it, since the ABS very seldom ever kicks in unless you're on a slick surface, and here in Houston, we don't get much ice, I'm going to unload this pretty soon anyway. It does not appear to be a serious issue, I guess this thing fails safe, and at worst case, I don't have ABS, so I'm essentially back to pre ABS days when you pump the breaks. THanks

astro01 · 11-13-2010, 07:13 PM

Hello, Did you ever figuer out the issue with the abs and brake lights coming on and off. Im having the same issue. Thanks

harryevan · 06-01-2011, 06:46 PM

I have a similar problem on a 2000 Astro AWD. Both the red BRAKE light and the ABS light come on at the same time, but intermittently after each startup/trip. It seems like it takes longer or doesn't even happen on wet days, and I have ABS when the lights are off, but don't after they come on. Brakes stay good and I'm not losing any brake fluid. This all resets with each start. Blue Bowtie said it sounded like a power problem in an earlier, similar thread. Are there connections that should be checked and cleaned, outside of the ABS sensors on the front wheels?

I had a '94 Lumina APV (another vehicle so good the think tank at GM discontinued it instead of improving it) that had a similar problem, and it took a rep from Detroit to find that a dashboard support was rubbing the wiring harness to the point of shorting the circuit and turning on the lights - but I was 29 days into the 30-days-in-service lemon law here in Colorado before he came in.

I just don't know where to begin to look. Looked over a Chiltons and a Haynes manual, but they were too vague when they DID talk about the second generation Astro/Safari's. So, where can I find a good (correct) wiring guide for a 2000 Astro AWD LT?

Thanks for the help.

94&92Astro · 06-04-2011, 06:53 PM

This is a common problem in later model Astro/Safari---It has something to do with the ABS electronic control module. There are a few ads on e-bay where they will rebuild and return. My 02 is having the same issue. I plan on having it rebuilt here http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT after I have eliminated other possible causes.

Leeann94astro · 06-05-2011, 08:36 PM

The Blazer guys have had good results with these guys if it is indeed an ABS module issue:

http://www.modulemaster.com/en/index.php

Blue Bowtie · 06-06-2011, 07:58 PM

The biggest problem is the power relay for the ABS, and it is buried in, you guessed it, the ABS unit on the frame rail. It's nearly impossible to access without removing the unit.

lilblkshp · 08-16-2011, 07:57 AM

blue bowtie is correct. its the internal relay inside ebcm getting stuck when it warms up( next to the exhaust) modulemasters does a great job and gives a 5 yr warranty.

davemt64 · 10-27-2011, 02:20 AM

Abs light and no trans. shifting FIXED. On mine the problem was a broken wire from the vss to the speed buffer. Speed buffer is located on the right side of the steering column. Mine has a white cover on it. That is also where I tested to make sure that was the problem.I ran two new wires to the vss ( vehicle speed sensor)from the speed buffer.This has been a 4 month ordeal,now I have to put a water pump on and some idler arms ,then I'll be good for awhile,thanks to all for your posts.

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