Dash brake light on

[snowball]

Hi all,

My dash brake light is always on. Can't pass inspection.

What should I look for?

[Bandit130]

Year, model, etc.?

[snowball]

Need to put all that in my signature

90 burn r1500 2wd 350.

Think it's a short in the engine bay...

[Bandit130]

Not too familiar with 90 model. I had this when brake was pressed when I purchased it in 2015. Mine was contaminated rear reservoir in master cylinder affecting proportioning valve. Had to replace and flush lines.

My first thought would be maybe e-brake switch or you could have a proportioning valve issue if yours has one. If you have owners manual, it may address an issue with brake light on. Mine does this.

[snowball]

Looks like a simple circuit. I disconnected the DRL, parking brake and proportioning valve. Light is still on.

[wilkin250r]

Check the easy things. If you actually, physically pull the brake pedal upwards, will it turn off?

[snowball]

It stays on. Doesn't get any brighter if you engage it

[snowball]

Just noticed the brake lights don't work. Not sure if it's related

[Bandit130]

Originally Posted by snowball

Just noticed the brake lights don't work. Not sure if it's related

Check brake fluid level too. Some models have a sensor that turns light on when level is low.

[snowball]

Nope its full.

[Pontiac1976]

check the wire on the brake proportioning valve @ the left frame rail (tan wire) should be a rubber hat over release but on end if it not rusted out or seized.

[Pontiac1976]

Other thing is the switch on the parking brake peddle ( the spring not holding the peddle up ) rear park cable stretched or sticking on lightly letting the e brake peddle fall down. The rear brakes shoes wear out to much.

[snowball]

how does that tan wire route?

I disconnected both those connectors and the light is still on.

[chengny]

Originally Posted by snowball

how does that tan wire route?

I disconnected both those connectors and the light is still on.

If you have RWAL brakes, be aware that the warning light for the e-brake/BPC valve is used by the RWAL system as well. In the event of a malfunction in the RWAL system, the ECU will keep the brake warning light illuminated.

To check if the warning lamp is on due to a problem with the RWAL braking system, pull the 6 pin connector from the ECU. The ECU for the RWAL's is mounted next to the master cylinder.

If doing that extinguishes the warning light, reconnect the harness to the ECU and pull any stored codes. Use the paper clip method and jump A to H in the ALDL.



If you have good eyes you can see the little letters - but A should be in the top row last pin on the right and H should be bottom row second pin from the left.

If you don't have RWAL brakes - disregard everything above.

[snowball]

I do have RWAL, but the module is bad so I just unplugged it.

[photo-tom]

As Pontiac stated, the proportioning valve may have moved and grounded out the brake light sensor that is attached to it. This happens when the system senses a loss in pressure or fluid, closing that part of the system off. This happened to me last week when I tried to bleed the rear brakes on my 94. I couldn't draw any fluid, and now my pedal goes to the floor, I have no rear brakes, and the light is on.

If this sounds like you, you'll need to reset the prop valve.

[snowball]

I found my problem. It's the wiring loom that goes over the block. The brake light wire's shielding went and is grounded.

What's the best way to repair this?