Intermittent Dash warning lights

[PanelDeland]

Hey guys,got a weird problem going on.It's been about a year (5000-7000 miles) since new brakes.MC is full,E-brake works great.74,000 miles on truck.No engine problems or brake problems ever,only service on this truck has been oil changes,a battery and 2 sets of brake pads.It's a 2000 Blazer with 4.3,AOD and 2wd.We've had it since new.

Sometimes the ABS and brake warning lights are coming on.They always come on normal when starting and may go off normal or not.The brakes work good and the truck drives normal.They sometimes come on while driving(randomly) and may or may not go off.This has been going on for about 6 weeks and is driving me nuts.I've had the codes read and it came up with only a O2 sensor.Replacing that didn't solve the brake light thing but it took a couple days before it did it again.I can't find a blown fuse(i replaced to be sure),a pinched wire or anything else.I checked brake linings and they are good,no leaks I can see and i can all but lock them up.I did hit the anti locks a couple times in the snow about the time this problem started.

Any Ideas?

I need to figure this out since the QOV is starting to talk new ride and I don't want the payment to replace a perfectly good low milage truck that's paid for and reliable.

[67ChevyRedneck]

Wow, WEIRD!!!

The ABS light came on my dime for the first time yesterday, so I spent some time on google.

I got some great info from these:

http://www.s10forum.com/forum/f14/ab...e-help-300032/

There's some really interesting stuff on here:

http://www.automotivehelper.com/topic503743.htm

Apparently, is a way too common issue. I already checked my grounds. About a month ago I noticed my ABS would very briefly pulse under very low speeds and only when I was turning/braking at the same time. Very seldom and random, no dummy lights. Then yesterday the ABS dummy light came on. Based on my readings, I think I need a new brake ECM.

[68C15]

who read the codes? a generic code reader (Auto Zone etc.) will only read engine codes. you would need one more professional (snap-on, OTC, Tech II)to get into the ABS system.

the red brake warning light and the ABS light come on together when there is a problem with the base foundation brake system which will affect ABS operation. being low on fluid would do that. in the master cylinder reservoir there is a float switch which senses fluid level. if the fluid is full try unplugging the connector while the lights are on. if they go out you most likely have a bad sensor or float is stuck. the sensor can be replaced without getting wet. it snaps into place on the outside of the reservoir. if the float is stuck there are a couple ways to resolve this. one is to remove the res. and clean it good with brake cleaner (total PITA). the other is to replace it. if you go with option #2 I suggest you replace the whole master. granted it is not causing trouble, YET, but it will.
good luck and keep us posted.

[PanelDeland]

Thanks for the info 68C15.Sounds like an easy check.Appriciate the help.

[68C15]

well? any news yet or are you like me, too busy to pay attention to your own ride.

[CRUBCHECKER]

You need to scan for codes in the abs module, and there should be codes stored in abs history. You need a decent scanner to do this and I don't think autozones will do the job. What I have seen is c0265 which is a pretty common code more so on silverados and tahoes/subs. What happens is the relay in the electronic brake control module or ebcm for short goes open randomly causing int abs brake lights. The reason I believe this is your issue is because you say the brakes work fine no leaks no brake pedal kick back which is the abs pump engaging because it thinks your skidding i.e. like a faulty speed sensor. Here is a bull on checking the ground before replacing the ebcm for like codes, but I would check the codes in abs history 1st.

PI00714A: Intermittent ABS Communication Codes - C0243 C0244 C0245 C0246 C0247 C0248 C0253 C0255 C0268 C0286 DTC U1031 U1041 - (May 19, 2003)


Subject: Intermittent ABS Communication Codes - C0243 C0244 C0245 C0246 C0247 C0248 C0253 C0255 C0268 C0286 DTC U1031 U1041


Models: .




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When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Condition/Concern:
Intermittent DTCs U1031, U1041, C0243, C0244, C0245, C0246, C0247, C0248, C0253, C0255, C0268, C0286

Recommendation/Instructions:
Follow the service manual diagnostic procedures and specifically check G110 at the radiator core support berfore replacing the EBCM. This ground is located on the driver side under the head lamp connections.

Inspect for looseness or corrosion.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

[CRUBCHECKER]

You need to scan for codes in the abs module, and there should be codes stored in abs history. You need a decent scanner to do this and I don't think autozones will do the job. What I have seen is c0265 which is a pretty common code more so on silverados and tahoes/subs. What happens is the relay in the electronic brake control module or ebcm for short goes open randomly causing int abs brake lights. The reason I believe this is your issue is because you say the brakes work fine no leaks no brake pedal kick back which is the abs pump engaging because it thinks your skidding i.e. like a faulty speed sensor. Here is a bull on checking the ground before replacing the ebcm for like codes, but I would check the codes in abs history 1st.

PI00714A: Intermittent ABS Communication Codes - C0243 C0244 C0245 C0246 C0247 C0248 C0253 C0255 C0268 C0286 DTC U1031 U1041 - (May 19, 2003)


Subject: Intermittent ABS Communication Codes - C0243 C0244 C0245 C0246 C0247 C0248 C0253 C0255 C0268 C0286 DTC U1031 U1041


Models: .




--------------------------------------------------------------------------------

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Condition/Concern:
Intermittent DTCs U1031, U1041, C0243, C0244, C0245, C0246, C0247, C0248, C0253, C0255, C0268, C0286

Recommendation/Instructions:
Follow the service manual diagnostic procedures and specifically check G110 at the radiator core support berfore replacing the EBCM. This ground is located on the driver side under the head lamp connections.

Inspect for looseness or corrosion.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

[Tink]

I had the same problem with my 2000 BlaZeR2. Check the primary ground for the brake actuator motor. It is located in the front clip behind the front drivers side head light assembly. In that location the elements rust the screw grounding it to the front clip. Clean the bolt and clip with a wire brush, ensuring you have bare metal to ground to.... use some dielectric grease and be done!