89 DeVille- here's a strange problem...

[Joel Den Haan]

On my 89 DeVille, under moderate to heavy acceleration, the brake warning light comes on until either engine speed picks up or I back off the gas. Often shows up when kicking down to second gear after rounding a corner. Service brakes are firm with no problems or variations in pressure. Light works normally to indicate parking brake operation- auto release now works just fine as well. 

I suspect some kind of electrical contact problem in the parking brake sender that turns on the light, or else some play somewhere that is allowing the pedal to move around under acceleration.  Any other ideas? Vacuum leaks affecting vacuum release motor when engine vacuum drops, perhaps?    Best fix?

Thanks,
Joel Den Haan#21586

[Roger H]

I think their are three ways to turn the light on, I would disconnect them one at a time and see when or if the problem stops to narrow it down

low brake fluid ( Have you checked the fluid level?)
park brake applied
proportioning valve  ( usually on frame below master cylinder follow brake lines from master cyl)

[Glen]

It’s also possible one of the wires is disconnected and grounding out as it moves under acceleration. 

The same thing could happen is there is a bare spot on the wire. 

Glen   

[Joel Den Haan]

I've checked and topped up the fluid level- we'll see if that is a solid fix for the problem.  Likely will get a brake fluid flush soon.

Thanks,
Joel Den Haan.