brake warning light problems

[Butters]

Here is one for the books. I have a problem with my brake warning light staying on after the engine revs to 3 grand or so. After it hit that point in a rev the light truns on and will not turn off. I have spend 3 days now trying to figure it out. I havbe just finish my turbo swap. you can shut off the car and start it back up and the light stays off but as soon as you rev it, that damn little light comes on and stairs at me. Also have noticed that the ecm light is comeing on and staying on when the brake warning light comes on.

 

I know its not the brake or the e-brake since it is unplug. so what could make the light do this on a rev. Other then that my car runs great.

 

I'll get some pictures for better clearity of how the ecm is wired up if it is that or if it was something i did?

 

I do know when I was trying to figure out my turn signals that when you add power to the flash to get the blinkers to work. the brake light was blinking instead of the lights front and rear of the car?

[roger.svoboda]

If you are getting a low brake fluid level signal then that light stays on until you replenish the fluid to the proper level. Did you disconnect anything from the brake fluid reservoir when you swapped stuff?

[Butters]

No. It has nothing to do with the brake fuild level. Unless it only turns on the brake light in the speedo, when you rev the engine past 3 thousand??

[BRAAP]

The brake light in the speedo of the S-30 is illuminated in the carious ways.

 

1) The parking brake being engaged, (switch is at the base of the parking brake handle)

 

2) A differential brake pressure switch in the engine bay just under the brake mastery cylinder. It has one wire going to it in the very middle.

 

3) The later S-30 cars, (for sure the ’78 model, possibly ’77) also utilized a brake fluid level switch with the switches in each of the master cylinder reservoir caps.

 

 

The light only illuminates if any of those switches close, (closed switch grounds the wire to negative/earth/ground, thus illuminating the light).

These conditions below can inadvertently cause the light to illuminate.

 

1) One of the wires is pinched/chafed and grounding out.

 

2) The open end of a connector from any of the switches that may be disconnected is touching grounding somehow.

 

3) Parking brake switch is overly sensitive and any bumping or vibrating of the parking brake handle allows that switch to close.

 

 

I have experienced the wire that goes to the parking brake shorting to ground due to someone rerouting that wire too close to the passenger seat track and the seat track wore through the insulation of that wire. Result was the brake light would flicker on and off. It got worse over time.

 

 

Based on what you’ve shared thus far, my gut instinct says it is a short, activated by the resonance the engine produces at 3000 RPM or so. Or the parking brake switch is overly sensitive/grounding out. Look at those various switches and any wiring to them that may have been chafed/damaged.

 

Hope that helps. If not, let us know what you do find.

[Butters]

So why dose the ecm light come on with the brake warning light? I gave the ecm its own switched and constant power source along with grounds.

 

Maybe the pictures will make things more clear i'll even try to get a video to help out. OH hell looks like I said that before guess i'll have to do it today.

[Butters]

OK. Still have not found anything that can turn the brake light on. everything is wired up like its suposed to. So I just pulled the bulb out and it started running better but that dose not mean much it is still bucking back and forth. Kinda feels like its contacting and then not contacting some thing in the tps but i'm a cat specialises. so when it comes to spark i have no clue? I'm so lost

 

Maybe this is the same problem i was having when i first got the car (Paul). But how knows?

 

Like today when i was driveing the car to get an inspection sticker. i only acted up after sitting at a stop light. it felt like it was loading up jsut sitting there. Then when crusing, it only bucked back and forth a little bit. But when you stood on the gas pedal, it acted like nother ever happend.