Brake warning light stays on - help please

[ichthos]

The brake warning light came on about a year after I totally redid the braking system on my TR6. The only thing I didn't touch at the time was the PDWA switch, which I just now rebuilt. After reinstalling the PDWA valve and bleeding the brakes, the brake warning light still stays on. I checked the brakes and there are no leaks. Any thoughts on what I am missing here?
Kevin

 

[TR4nut]

Do you have the PDWA valve centralized? When you bleed the brakes, you need to be careful otherwise that switch will kick in. This may not be the best way to diagnose, but I'd bleed again, crack the front or back side and push on the brake - if you've picked the correct end to start from, the shuttle in the PDWA will move over and the light will go out. If not, bleed the other end and see if you can get it to kick over.

 

[hondo402000]

well easiest way to find out is to un plug the wire going to the switch, if the light goes out its switch related, or the PDWA has shifted, since the circuit is just a grounding circuit, if you unplug the wire and the light still stays on the circuit is grounding somewhere

Hondo

 

[hondo402000]

and ps when you turn the IG on the light is suppose to light up as a safety so you know the bulb is not burned out but upon starting the car the light goes out, if it stays on while the car is running then check as I stated above

Hondo

 

[DrEntropy]

Can't recall but: is there a switch at the handbrake lever too?

 

[Gliderman8]

Can't recall but: is there a switch at the handbrake lever too?

I beleive the handbrake switch was only on later cars, but you might check to see if a PO installed one as doc suggests.

 

[ichthos]

Thanks, guys. I will check things out when I get home from work. I will let you know how it turns out.
Kevin

 

[DNK]

From Work???... you get a summer job?
Kevin my guess is you got the wire grounded somewhere. That's how it works

 

[ichthos]

Don, I either have meetings during the summer or have to go to school during that time. Today it was another exciting meeting.

So, I took the wire off of the switch, and the brake warning sign still stays on. That rules out the switch (for now), but how do I find where it is grounding? I noticed it after the new engine was put in.

Kevin

 

[DNK]

Your gonna have to trace that wire . Unplug it from the light and then ...
Geez, I don't know. Run a new one??

 

[Gliderman8]

Kevin- Did you check to see if there is a emergency brake switch as doc suggested? It is possible that someone added this switch to the handbrake... just a thought.

 

[poolboy]

If the "Brake" light is on and it's not because the wire to the PDWA is grounded, then look to the Oil Pressure switch..The PDWA/BRAKE light circuit and the Oil Pressure warning light are related, electrically speaking.
If the OP switch grounds either due to low OP or a faulty switch, the "BRAKE" light will glow and the OP warning light will glow, although that light is hard to see lit in daylight..
However if the OP switch is working correctly and not grounded, a grounding of the PDWA wire will only illuminate the "BRAKE" light.

 

[TR3driver]

Don't mean to be picky, Kevin, but it would help if you would tell us what year TR6. They aren't all wired the same.

Assuming you have one of the ones that uses the oil pressure switch for the "bulb test" function, my next step would be to pull the wire(s) off the oil pressure switch. Especially since the problem showed up after an engine rebuild.

If no joy there, I'd try to do a visual on as much of the harness as you can; then maybe try the compass trick. Or just run a bunch of current through the short and feel around for where it gets hot.

 

[DNK]

He's got a 69

 

[poolboy]

Pretty sure he's got a 69.

 

[TR3driver]

He did pull it Randall

Err, he said "the" switch. Was that the oil pressure switch, or the PDWA switch? If he pulled both wires off, he should have said so ...

 

[ichthos]

Hi guys - yes it is a 69. It does not have a hand brake switch. All I have done so far is remove the wire to the PDWA switch and the brake warning light still stayed on. As suggested I pulled the wire off of the oil pressure switch and the brake light doesn't come on even when I first start the engine now. I didn't realize the two were related in any way. I am still confused. The oil pressure switch is fairly new, but does this mean the oil pressure switch is bad?
Kevin

 

[TR3driver]

It's kind of a strange system, but the oil pressure switch provides a "bulb test" function for the brake warning light.

Assuming the oil pressure gauge shows pressure, then a bad switch is the most likely explanation. A 69 would have the single-terminal switch, so no question of the wires being installed wrong.

 

[ichthos]

My oil pressure gauge is working and shows good oil pressure. I will swap out one of my old oil pressure switches for my new one and see what happens.
Kevin

 

[poolboy]

When you get a little extra cash, Kevin, you really should get Dan Master's "Electrical Maintenance Handbook" for the Triumph TR250-TR6

I don;t know how I got along without it for the first year I owned a TR6.
It's written in plain language with diagrams or photos of what he's discussing.