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Brake light failure relay on 1992 245

It looks like my brake light failure relay is broke- I step on the brakes, the fail light goes on and 12V doesn't go to the brake lights .

First I thought no problem, I'll just do the dashboard dive and get to the bottom off this. The brake pedal switch is good, and I decided to bypass the relay after I saw that blue/red wire disapear into wire harness and dashboard.

I tried bypassing the relay and using the brake pedal switch to feed

12V lights up the lights, but then I can't shift out of park since this relay is actually the hidden nexus of all things volvo. Wiring the relay right to 12V works if you want a couple brake lights on 24-7. Not.

So I'm left finding the relay (relay 12 at D5 in the generic 240 wiring diagram). Can anyone tell me where it is in dashboard land and how to get there? I've got the sinking feeling that it's gonna be like a heater motor- step 1: Pull the speedometer =8-0

Reply to
moon161
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Relay? Or are you referring to the bulb failure sensor which is normally a red cannister with a lot of wires going to it?

Reply to
James Sweet

Sounds right to me. Pictures I've seen of it look like a can. It's fed by blue/red from the brake pedal sensor, and should output to the instrument cluster, brake lites and the shifter interlock. Once found, can pop it open and see if it's a relay inside or otherwise.

I looked in the console, and behind the radio, but haven't pulled the speedometer yet. Sounds like I better change the wires over one by one ;0)

Reply to
moon161

The older ones have a number of glass reed relays, each has two coils wound around it in opposite directions. These coils are in series with the lamps, one on each side. When the load is equal (both lamps working) the magnetic fields cancel out. When one lamp is working and the other isn't, you have a field which activates the reed relay turning on the dash indicator.

Newer ones I hear are electronic, I haven't opened one of them up yet.

Reply to
James Sweet

Cool. Do you know exactly what part of the dashboard forest to look in? I've looked around the pedals & steering column, behind the radio, and pulled the center console.

Thanks,

Andy

Reply to
moon161

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