Brake Light On Dash

[Justin Fleming]

1990 k5, it never fails my dad borrows the truck and now it comes back with the brake light on. I assumed maybe he hit the ebrake maybe getting in and out. not the case, so I reached under the dash and unplugged the lead going to the break light switch and the light stayed on, when out under the hood and discoonedted the 1 wire lead going to the portioning block I beleive is what that would be and the light stayed on. Fluid level is good and brakes funtion well.

Where should I be looking next?

 

[diesel4me]

If you unplugged the tan wire going to the proportioning valve and the light still stays on,I'd say it's probably being activated by the E-brake ,even though the brake is "off"...maybe the wire to the e-brake switch is pinched or came off and grounded,which will turn on the light..

 

[dremu]

Is the light steady on, or blinking?

1990-91 Blazers/Burbs had an early ABS system which is famous for failing. If the light blinks, the ABS module is angry about something. Many folks just unplug its wiring harness (by the master cylinder) and call it good.

If the light is on steadily, there are two possible causes. One is the parking brake pedal and the other is the proportioning valve.

If you've unplugged the second one, then the parking brake wiring is the only possibility left. As mentioned, it might be frayed or loose.

-- A

 

[Justin Fleming]

Is the light steady on, or blinking?

1990-91 Blazers/Burbs had an early ABS system which is famous for breaking. If the light blinks, the ABS module is angry about something. Many folks just unplug its wiring harness (by the master cylinder) and call it good.

If the light is on steadily, there are two possible causes. One is the parking brake pedal and the other is the proportioning valve.

If you've unplugged the second one, then the parking brake wiring is the only possibility left. As mentioned, it might be frayed or loose.

-- A

I have actually unplugged both the ebrake switch and portioning and the light is still on....is the lead going to the ebrake a hot wire or ground wire

It is a steady on light..... not blinking....

 

[scottsdale86]

stop letting your father use your truck. Problem solved. Check the abs ring or the sensor.

 

[dremu]

I have actually unplugged both the ebrake switch and portioning and the light is still on....is the lead going to the ebrake a hot wire or ground wire

It is a steady on light..... not blinking....

I don't have one of these era trucks any more to look at, so we'll hafta wait for somebody else to chime in about the wiring to the parking brake pedal. (In your OP you said "brake pedal" and I thought you meant the main purple & black on the actual brake pedal, not the whatever at the parking brake pedal, my bad.)

You can also unplug the harness on the ABS module and see if the light goes away. Maybe the module is fried and has the light on all the time. (The ABS is only on the rear wheels and only in high gear, so it's not the end of the world if you go without it.)

-- A