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Just bought an '88 Sportswagon.

PO has wired up a third brake light, but every time I hit the brake, the brake warning light comes on.

What triggers the light, and any tips on what to do ? He said it only started when he added the third lamp. Obvious solution is to remove the third lamp, but Canberra drivers suck, so I'd liek to keep it, if I can understand why it's coming on.

Thanks.

the brake fluid warning comes on? if thats so it is triggered by the depth floatie in the resevoir. but that couldnt be triggered by ur situation.
i spose im no help then.

my Brumby brake warning light comes on whenever a trailer and lights are hooked up. By adding a third light you may have altered somethin'. But then my third centre light don't cause any probs?

mroberts wrote:Just bought an '88 Sportswagon.

PO has wired up a third brake light, but every time I hit the brake, the brake warning light comes on.

What triggers the light, and any tips on what to do ? He said it only started when he added the third lamp. Obvious solution is to remove the third lamp, but Canberra drivers suck, so I'd liek to keep it, if I can understand why it's coming on.

Thanks.

The light should be triggered by the brake light switch under the dash and behind/above the pedal, as are the tail lights, it may be that he has tried to splice into one of these wires, rear loom runs along the drivers side, it's a safe bet to start there, behind the rear tail light. I've come across this problems a few times, it's usually due to shoddy trailer wiring, to be sure, disconnect the third light from it's join, if the problem stops, his connection was causing a short, if not the short could be further up or you really don't have any brakes, has anybody checked?

My MY did the same thing when a trailer was connected, I figured the light is based on some sort of metering circuit and comes on when current draw is outside specific parameters.

Don't know if this helps, but may give you a rough idea.

Jordan.

Hey MRoberts - are you referring to the "Stop Lamp" light just below the instrument cluster? That is supposed to light up every time you push the brake pedal and there is a blown bulb.

A wiring diagram might be your friend.

Fang wrote:Hey MRoberts - are you referring to the "Stop Lamp" light just below the instrument cluster? That is supposed to light up every time you push the brake pedal and there is a blown bulb.

A wiring diagram might be your friend.

That's the one. I'm bidding on a manual on eBay, so I should have that soon.

redskin wrote:or you really don't have any brakes, has anybody checked?

Fair point ... the car is so slow I may not have noticed the brakes don't work, the drivetrain losses may be what's slowing it down

Yep, sounds like a blown stop light bulb.

I had a similar problem in my 87 wagon - turned out to be the brake light detection circuit which is a small printed circuit board contained in the drivers side rear light assembly. It is hard wired into rear light assembly wiring loom and I 'fixed' it by replacing wiring loom with a spare that I had.
(I'm sure you could somehow simply bypass the circuit...any clues anyone?)

you can bypass it as they do burn out from time to time

Run the high stop / third light off a relay, so instead of drawing current directly from the existing circut, it can take it from the battery (and not cause the warning light to come on).