Help with brake light problem

2000 GMC Savanah 3500

With headlight switch in OFF position the brake lights work normally.

With headlight switch in either ON or driving light position: brake lights on left and right stay on unless brake is pressed, then they go off (backwards yes?) but the top center brake light continues to work normally - off until brakes are pressed then on.

Dealer says it is probably the brake switch or a relay. However they say it may take quite a while to diagnose and they have to charge for the time. Can I troubleshoot this myself?

Suggestions?

(please respond to news group as my email is spam blocked)

Reply to
Rogers PCS User
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bad ground for the lower lamp assemblies

Reply to
Gary Glaenzer

There is no "driving light" position. Do you mean the *parking lamp* (first click) position?

Yes. Backwards.

The Center High Mount Brake Light is on a separate switch contact.

There is no relay in the brake lamp circuit.

Well, they do have to charge for diagnostic time, but the brake lamp circuit is *very* simple, so I can't really see it taking a lot of time.

Are you handy with a voltmeter, continuity tester and/or test light?

Most likely cause here is a faulty brake lamp switch. Second most likely is a wiring problem. Faulty grounds can cause crossed-up functioning like this.

DS

Reply to
Daniel Stern Lighting

That's my guess too. I would go to the light fictures and find where they ground to the vehicle. I would then pull the connection and clean the connection and re-asseble.

----------------- Alex __O _-\

Reply to
Alex Rodriguez

The bad ground therory is good but since the bulbs act normally until you apply power to the park lamp wire I say the ground is good Does the truck have a pig tail for a trailer if so check there first also have you had any bulbs replaced recently?

Reply to
jhones.family

The bulb is grounding through the parking light filaments in all the other bulbs that come on with the parking light switch. Check the ground for the malfunctioning bulb.

Chris

----- Original Message ----- From: "jhones.family" Newsgroups: alt.trucks.chevy,alt.autos.gm,rec.autos.tech Sent: Monday, August 11, 2003 8:20 PM Subject: Re: Help with brake light problem

Reply to
Chris Morda

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