Brake light stays on

cgabe · December 11, 2003

I have a 91 GMC Jimmy full size with a 5.7L TBI. About a year

ago the brake light came on. At first (that means still last year) it would come on, stay on for about 5 min. then it would start blinking 9 times fast and the 10th time it would stay on just a bit longer. This would happen over and over again, the blinking that is.

At first I thought the number of blinkings was some sort of a code but no one could tell me if that was so.

The truck sat for a while (blew the stock 10 bolt , now I've got a 14 bolt w/ disk brakes ) and when I fired it up the brake light just stays on constantly.

I've checked everything... brake fluid level , bled the brakes many times and nothing.

What I think is strange is that the brakes work just fine and they have been all this time.

Little help please, anybody?

MountaineerTom · December 11, 2003

Are you talking about the brake light on the instrument cluster, or the brake lights in the tailights?

If it's the tailights, it might be your switch under the brake pedal, on the firewall, going/gone bad.

cgabe · December 11, 2003

The brake light in the dash, not the taillight...

MountaineerTom · December 11, 2003

Hmm,

I'd check the parking brake and see if there is a switch that is bad or something may just need adjusting.

cgabe · December 13, 2003

I've checked the e-brake switch too and it's fine.

You know , when your truck is low on brake fluid the brake light comes on the daskboard, and then you apply the e-brake and the brake light gets even brighter? My truck does just that . Still that horrible light starea at me.

Pewter Pro-Tec · December 14, 2003

I've checked the e-brake switch too and it's fine.
You know , when your truck is low on brake fluid the brake light comes on the daskboard, and then you apply the e-brake and the brake light gets even brighter? My truck does just that . Still that horrible light starea at me.

Does your truck have ABS? It sounds like the warning light is trying to tell you that the anti-lock braking system may need work.

Might be a dirty sensor or something like that but your regular brakes will work, but you will not have anti-lock functions.

cgabe · December 14, 2003

The truck has solid axle front and rear and I didn't notice any sensors on them

The rear axle is a 14 bolt corp.(swapt in) and for sure the old 10 bolt had no sensors on it.

But now that you mention it , I did notice that the brake lines coming out of the reservore lead into some sort of a box first, and I dont know what it is . could that be the ABS control unit? If so, where are the sensors?

Pewter Pro-Tec · December 15, 2003

The truck has solid axle front and rear and I didn't notice any sensors on them
The rear axle is a 14 bolt corp.(swapt in) and for sure the old 10 bolt had no sensors on it.

But now that you mention it , I did notice that the brake lines coming out of the reservore lead into some sort of a box first, and I dont know what it is . could that be the ABS control unit? If so, where are the sensors?

If I remember correctly, that year truck has only rear ABS. If so, the sensor should be somewhere on the top of the third member, where it can "read" how fast the ring gear is going. You may be able to unbolt that sensor and see if it is covered with debris.

OOPS, I just read your post more carefully and you said it had a swapped in rear end. If that is the case, and you have 4-wheel ABS, the sensors for the front are behind the front rotor, you will see a toothed ring gear on the CV shafts and the sensors should be close by. Again, I'm not sure if you have 4-wheel ABS or if you even have ABS. Maybe someone can confirm that for you.

1500HD4x4 · February 11, 2004

I own a 1990 Chevrolet V1500 full size Blazer, 350TBI, 4L60 with RWAL, rear wheel anti lock brakes. About 9 months ago my brake light also came on and stayed on. The brakes, like yours, seemed to be OK. Then one day the brake light started blinking, 1 long, 9 short, just like yours. I asked a mechanic where I work if we had a book with brake codes, no luck. So he said, just unplug the two weather-pak connectors on the black box by the brake booster/master cylinder. Making sure that the ignition is off!! This will clear any codes, it may have been a false code. Viola!! The light is off and it is not blinking.