Brake Warning Light Problem

Jessie · 02-09-2008, 04:32 PM

I have a 1988 chev silverado 3500 with rwal brakes that I can't get the brake warning light to go off. I've replaced the pads and shoes and have completely flushed the system. All wheels seem to have equal pressure and the brakes seem to work fine. The light will not go off and that worries me. Any suggestions?

436'd skylark · 02-09-2008, 04:42 PM

Did you make sure the e-brake was up all the way?

The brake light will turn on if there is a problem with the ABS system. trying unplugging the ABS computer (right below the master) and see if the light goes out.

ukrkoz · 02-09-2008, 04:52 PM

Quote:

Originally Posted by Jessie

I have a 1988 chev silverado 3500 with rwal brakes that I can't get the brake warning light to go off. I've replaced the pads and shoes and have completely flushed the system. All wheels seem to have equal pressure and the brakes seem to work fine. The light will not go off and that worries me. Any suggestions?

does it have brake fluid level sensor? if yes, you probably low on fluid. buddy disassembled half of his mazda for the same reason once.
also, you might have stuck or faulty parking brake sensor. find it and clean it or disconnect harness.
they did not have ALB in 88, did they?

o3shortbed · 02-09-2008, 06:54 PM

my 90 chevy didnt have alb's and i doubt an 88 did but i could be wrong. does the booster have lines that run to the power steering box?

Jessie · 02-10-2008, 11:21 AM

Yes it has lines running to the power steering pump but it does not have a booster. It has an electric motor/pump which acts as the booster. I've checked the parking brake sensor and its ok. The sticker in the glove box indicates that it has rwal. It does not have a master cylinder fluid sensor. I will try unplugging the computer under the master cylinder to see what happens.

mudseeker · 02-10-2008, 02:09 PM

which brake light is lit on your dash, the ABS or BRAKE?

crabtruck · 02-11-2008, 01:09 AM

On the older trucks there was only one light for e-brake/pressure/rwal
even though there were seperate pics on the dash.
Might try unplugging wire from combo valve.
Instead of relying on the sticker to see if rwal is actually there,
look at the brake lines coming from combo valve.
If there's another set of valves with wires to a control box,
you might have rwal.

Might look a little like this:

Case 7230 · 02-11-2008, 06:01 AM

Did the light come on after you did the brake job? It may be that the pressure diferential switch needs reset. Try opening a rear bleed screw and get a helper to gently press the pedal. If the light goes out tighten screw and let pedal up. If light does not go out repeat with a front bleed screw. It is a matter of getting the valve reset to the central position. It may have been pushed to one side or the other when you flushed the system.

Jessie · 02-11-2008, 08:06 PM

The light was on before I did the brakes. Rear brakes completely worn out. Crabtruck that pic is the brake system on this truck as far as I can tell from the pic. Problem may be in the control there, I don't know but like I said the brakes seem to work fine. I took it out and tryed them and put them to the test. I'll say this and that is this is the first truck I've had that has any computer in it. May be why I am having such problems. I have and drive a 49 chev pu, 66 chev pu, 71 chev 1 ton, a 55 belair, 65 SS Impala and 66 olds 442. I done all the work to all of these vehicles including brakes and have never had a problem like I'm experiencing now . I' m about ready to let this one go down the road.

crabtruck · 02-11-2008, 11:54 PM

BTW, welcome to the forum Jessie.
Don't let the red light give you the red light.
Not too much "computer" involved with the brakes.

Try disconnecting the wire from the combo valve first as most likely cause,
since brakes were shot. E-brake off when you do that, since the red light
serves 3 purposes: e-brake, pressure(combo), and rwal.
RWAL should not be a problem unless you drew air in from the top to
valves. E-brake switch should be easy to check wires on.

First check before getting hands dirty:
with key on, e-brake off, and lamp check over:
apply e-brake while watching light closely.
If E-brake ok, the light will brighten just so very slightly.
I forget which is dimmer of the other two: rwal / combo.
The 3 causes are at different brightnesses, but very very small difference.

02-09-2008, 04:32 PM	#1
Jessie Senior Member Join Date: Feb 2008 Posts: 94	Brake Warning Light Problem I have a 1988 chev silverado 3500 with rwal brakes that I can't get the brake warning light to go off. I've replaced the pads and shoes and have completely flushed the system. All wheels seem to have equal pressure and the brakes seem to work fine. The light will not go off and that worries me. Any suggestions? Last edited by Jessie; 02-09-2008 at 04:38 PM. Reason: left out part of the decription

02-09-2008, 04:42 PM	#2
436'd skylark Senior Member Join Date: Mar 2007 Location: Buffalo Ny Posts: 661	Did you make sure the e-brake was up all the way? The brake light will turn on if there is a problem with the ABS system. trying unplugging the ABS computer (right below the master) and see if the light goes out. __________________ Joe 89 K2500 Chevy, Wee-Oh-five 285K miles, completly rebuilt needs a motor, bad 1962 IHC Scout All Wheel Drive (Scout speak for locking axles) 152 ci, dana everything else

02-09-2008, 06:54 PM	#4
o3shortbed Senior Member Join Date: Jan 2008 Location: L-burg KY Posts: 334	my 90 chevy didnt have alb's and i doubt an 88 did but i could be wrong. does the booster have lines that run to the power steering box? __________________ 1998 Jeep Grand Cherokee Limited 5.2 Full time 4WD NP249

02-10-2008, 02:09 PM	#6
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 6,373	which brake light is lit on your dash, the ABS or BRAKE? __________________ i'd rather be hunting

02-11-2008, 01:09 AM	#7
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,364	On the older trucks there was only one light for e-brake/pressure/rwal even though there were seperate pics on the dash. Might try unplugging wire from combo valve. Instead of relying on the sticker to see if rwal is actually there, look at the brake lines coming from combo valve. If there's another set of valves with wires to a control box, you might have rwal. Might look a little like this: Attached Thumbnails

02-10-2008, 11:21 AM	#5
Jessie Senior Member Join Date: Feb 2008 Posts: 94	Yes it has lines running to the power steering pump but it does not have a booster. It has an electric motor/pump which acts as the booster. I've checked the parking brake sensor and its ok. The sticker in the glove box indicates that it has rwal. It does not have a master cylinder fluid sensor. I will try unplugging the computer under the master cylinder to see what happens.

02-11-2008, 06:01 AM	#8
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	Did the light come on after you did the brake job? It may be that the pressure diferential switch needs reset. Try opening a rear bleed screw and get a helper to gently press the pedal. If the light goes out tighten screw and let pedal up. If light does not go out repeat with a front bleed screw. It is a matter of getting the valve reset to the central position. It may have been pushed to one side or the other when you flushed the system.

02-11-2008, 08:06 PM	#9
Jessie Senior Member Join Date: Feb 2008 Posts: 94	The light was on before I did the brakes. Rear brakes completely worn out. Crabtruck that pic is the brake system on this truck as far as I can tell from the pic. Problem may be in the control there, I don't know but like I said the brakes seem to work fine. I took it out and tryed them and put them to the test. I'll say this and that is this is the first truck I've had that has any computer in it. May be why I am having such problems. I have and drive a 49 chev pu, 66 chev pu, 71 chev 1 ton, a 55 belair, 65 SS Impala and 66 olds 442. I done all the work to all of these vehicles including brakes and have never had a problem like I'm experiencing now . I' m about ready to let this one go down the road.

02-11-2008, 11:54 PM	#10
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,364	BTW, welcome to the forum Jessie. Don't let the red light give you the red light. Not too much "computer" involved with the brakes. Try disconnecting the wire from the combo valve first as most likely cause, since brakes were shot. E-brake off when you do that, since the red light serves 3 purposes: e-brake, pressure(combo), and rwal. RWAL should not be a problem unless you drew air in from the top to valves. E-brake switch should be easy to check wires on. First check before getting hands dirty: with key on, e-brake off, and lamp check over: apply e-brake while watching light closely. If E-brake ok, the light will brighten just so very slightly. I forget which is dimmer of the other two: rwal / combo. The 3 causes are at different brightnesses, but very very small difference.

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