Brake Light Keeps Going On And Off On Dashboard

Brakes replaced last year all the way around. Have noticed this summer the brake light on dashboard will go on and stay on intermittently and then go off. Will go on once in a while when making turns. I have chequed the fluid numerous times and it is fine. Perhaps a short but have nowhere to begin. Have chequed the plugs going into the master cylinder and they seem to be solid.

What MY car is this? Specifically, which brake system?

Hello Richard - as per my service manual update information for the MY 1989, the brake reservoir contains three fluid level operated reed switches. Two “normally open” switches light the BRAKE FAILURE warning if the level drops too low. The third “normally closed” switch signals the ECU if the level drops below a minimum level for full ABS operation. In this case, the ECU switches off the front wheel ABS and lights the ABS warning. Since you state that you have checked the fluid numerous times, and it is fine, you may have one of the “normally open” switches failing intermittently into a “closed” position, which would then allow a ground signal to activate the brake failure warning - I suggest that you check the wiring at the reservoir and the switch contacts - Tex Terry, II - 1991, XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 9/11/2020 1436hrs. EDT USA.

It is very common for the sender inside the brake fluid reservoir cap to go bad. Mine did the same, replaced with new cap, all good.

That does not sound complicated…thank you.

That would be the 1989 Jaguar XJS.

Greg…took a look at the cap and all I saw was a rubber top part. Are you telling me the cap is defective as it is leaking air or not sealing properly?

Greg’s 88 my does not use teves 3 , so the comment about a switch in the cap means squat to you. You need to study YOUR brake system, then listers responses will make more sense to you.

Did that year have sensors on the brake pads?

Yes and they work well…had new system put in last year.

Yes, mine is 88, before abs and before Teves (thank god!)

Original post didn’t say what type of brake system, no mention of teves or abs, so I assumed it was like mine.

Well then, what does that mean about mine?

I do not have a clue.
And neither do you.

You my friend are correct on both counts…guilty as charged.

If that photo is something modified that you are discussing…then maybe the regular rules are off the table

Did you do Sturgis - and avoid the virus?

Nothing is modified in this car…It’s like Mr. Natural.

No, we didn’t do Sturgis…we are to far as we live in Syracuse, New York but…lots of cooties from the students back from holiday at Syracuse University…might be the same thing.