When i hit the throttle or even under normal acceleration my brake warning light turns on and flashes then when i hit around 30 mph it turns off. it does not come on while braking or when stopped at a red light. i ran the code reader and it had no codes. my inspection is due next month so need to get this done asap. thanks
CK5
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Brake warning light flashes during acceleration
- Thread starter p.o.s 78
- Start date
I'm gonna bet this is a 1990 or 1991 Blazer or Suburban?
If so, you have the (in)famous rear wheel only ABS system. Many folks, myself included, have quietly disconnected the wiring at the module (under the hood by the brake booster) with no ill effects. (There may be a separate fuse for it under the dash, in which case pulling it is simplest.) This ABS only works when in 2WD mode and, in my experience, only works on alternate Tuesdays.
Without the computer connected, the brakes still work as normal.
If you do desire or are required to fix it, the blinking will be in a pattern of fast blinks and slow blinks. If memory serves, the first set is the tens digit and the second the ones, so four blinks of one speed, then five of the other is 4, 5 == code 45. Then you Google this and try and sort out what's wrong.
If this is an older truck (i.e. 1978, from your username) then you have a whole other set of troubles, but post up and we can walk you through that situation.
-- A
If so, you have the (in)famous rear wheel only ABS system. Many folks, myself included, have quietly disconnected the wiring at the module (under the hood by the brake booster) with no ill effects. (There may be a separate fuse for it under the dash, in which case pulling it is simplest.) This ABS only works when in 2WD mode and, in my experience, only works on alternate Tuesdays.
Without the computer connected, the brakes still work as normal.
If you do desire or are required to fix it, the blinking will be in a pattern of fast blinks and slow blinks. If memory serves, the first set is the tens digit and the second the ones, so four blinks of one speed, then five of the other is 4, 5 == code 45. Then you Google this and try and sort out what's wrong.
If this is an older truck (i.e. 1978, from your username) then you have a whole other set of troubles, but post up and we can walk you through that situation.
-- A
Well, making some guesses here. `If its actually a 78 Blazer like your name says, then there is not a lot that should turn on the light.
The emergency brake switch will I think, its usually a loose bracket or pedal that hits the switch.
Try wiggling the pedal to see if the light comes on.
Otherwise, its the proportioning valve/unequal pressure switch. Not sure how it could be doing it under acceleration, but maybe a shorted wire since it grounds to turn on the light.
If its newer, then the master cylinder has a low fluid warning switch in the reservoir. If the fluid level is right at the point of triggering the switch, it might slosh enough to do it.
If its even newer, then there might be something in the antilock module that is causing it.
The emergency brake switch will I think, its usually a loose bracket or pedal that hits the switch.
Try wiggling the pedal to see if the light comes on.
Otherwise, its the proportioning valve/unequal pressure switch. Not sure how it could be doing it under acceleration, but maybe a shorted wire since it grounds to turn on the light.
If its newer, then the master cylinder has a low fluid warning switch in the reservoir. If the fluid level is right at the point of triggering the switch, it might slosh enough to do it.
If its even newer, then there might be something in the antilock module that is causing it.
No pix, haven't had that truck in aeons. The vacuum booster is the steel donut a foot in diameter above the steering column. The only black box on/around it with wires is the ABS computer, can't miss it. Might say "KH" on it (Kelsey-Hayes, made it for GM.) Or look in the fusebox for "ABS".
And Fordum, ain't none of the 70's/80's Chebbies have anything electric in the master. The combo valve is the prop valve and pressure imbalance switch all in one, and it and the parking brake lever are the only thing that drive the brake light on the older trucks.
-- A
Yep, I knew that. What I didn't know was what decade or century his truck was. So, I started old and worked my way up to new.
Don't know when they started putting the low level in the MC, but pretty sure the newer ones have it.
And could not think of the term "combo valve" off the top of my head, so I went with a description.
Plus, I had to stop writing and run outside to shoot a Coon that was looking for my old rooster in the Cedar tree.
Spotted him on the front cam, switched to the North cam, and saw him headed up the tree.
He won't be doing that, or much of anything else, again.
mr250twostroke
1/2 ton status
Hmmm... funny
