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97 Chevy 1500 P/U 4.3L - brake light issue.
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mmook87
New User
Nov 25, 2013, 11:29 PM
Post #1 of 14
(1672 views)
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97 Chevy 1500 P/U 4.3L - brake light issue.
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I have an issue that has stumped a few mechanics and I've not found the same issue elsewhere on the web. Any help would be greatly appreciated.
When I push down on the brake pedal my brake lights in the rear of the truck come on. As the pedal goes down the lights go out. I can hold the brake pedal pushed in just a little at a position that keeps the lights on. I had a shop install a new brake light switch and that didn't correct the problem. I've had two other mechanics look it over and inspect the wiring and anything else that it could be and no answers.
I had the rear brakes inspected and they are in good working order. I just had pads, calipers and rotors installed in the front. I'm replacing a leaky master cylinder tomorrow.
I can hear the click of the switch on and off as the brake pedal gets pushed in. There is a small amount of play and wiggle in the brake pedal but is tight above at the bolting area. the one Mechanic thought that maybe the brake pedal assembly and linkage had worn away and isn't keeping the switch pushed in.
Someone at the auto parts store said that maybe a relay or something (not using the right term here) in a box under the hood was switching it off and then resetting itself?
Thanks for your time if you read this and hopefully you can help out.
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 26, 2013, 3:25 AM
Post #2 of 14
(1654 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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If the position of the brake pedal is the thing that triggers the change, then the problem can only be in the area of the brake switch. I don't know who you are using for mechanics but it doesn't take a rocket scientist to determine if the signal is being cut out at the switch or not.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 26, 2013, 4:43 AM
Post #3 of 14
(1647 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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Watching and with Hammer completely. Pedal could fall off and switch should keep brake lights on so mechanics didn't spend much time OR slight real chance that body of the truck bed just doesn't have enough ground. Ground to frame up front to frame still needs to ground all over including the bed which is setting on rubber. Why it would care about pedal position doesn't make much sense.
Does the third brake light, high on roof work on truck body while rear lights quit?
T
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mmook87
New User
Nov 26, 2013, 2:47 PM
Post #4 of 14
(1633 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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Thanks for the reply. I am looking into the grounding situation. I have been doing some research and reading on the matter.
I do have a third upper light and it works it is acting up in unison with the brake lights. If they are on so is the third upper and it goes off with the brake lights.
Underneath and to the rear of the truck are two wires that I think are the brake ground wires. One is black and one is white and come from the harness that splits off toward both brake lights. Where it connects to the underside it is very rusty and mucked up. I am going to redo the ground at that point.
One item I didn't mention earlier was that days before I became aware of the light issue I installed a new thermostat. On the thermostat housing is a ground wire. Ive cleaned and rechecked that and it seems to be fine.
Any other thoughts would be appreciated.
I'm also going to replace the Brake relay fuse and the brake light fuse.
Ive run in to a few stories that it could be the turn signal switch. For these trucks it seems to cause some brake light issues.
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mmook87
New User
Nov 26, 2013, 2:52 PM
Post #5 of 14
(1629 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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Hi Hammer. Thanks for your reply. One place was Firestone and the other was a Mechanic with a shop on our main street for many years. I'm unsure of how much looking into the issue they did after both saying the switch is good. I'm looking into some possible grounding issues. Mainly in the underside back middle. I thinks the two wires (1black and 1 white) attached to the frame is very rusty and corroded.
How would one go about determining if the signal is being cut out at the switch? Thanks for your time on this.
Regards,
Mike
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 26, 2013, 3:16 PM
Post #6 of 14
(1626 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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OK - I just happen to own a 97 2500 - should be same and will look where ground strap is if needed. They are all over vehicles and either break or lose it. Lighting in general wouldn't waste a separate wire for each all the way back to where they get power and never did.
Kinda redneck ways to test for grounds way back there is to use a set of jumper cables from battery + 'Positive' and jumper wire with alligator clips at both ends. Then with a "T-pin", safety pin, fine panel nail or what works you can probe back side of sockets with that Bat + to a simple 12V test light. It should light anywhere you touch good ground.
Now the disclaimer. AYOR with tricks like that and always best to fuse anything you are playing with. This is just bulbs and sockets. Don't be creative testing other things.
This really shouldn't be rocket science if power leave the brake switch and makes it to rear sockets then only ground is lost somewhere,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 26, 2013, 3:37 PM
Post #7 of 14
(1621 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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You're making this a lot more complicated than it really is. There is a power wire leaving the brake light switch. If somebody simply monitored the voltage leaving on that wire while the problem occurs, it will easily answer the question if the switch is at fault. Any decent tech should know that. You don't have a ground issue. The turn signals share the same bulb and circuit. If the turn signals work, the grounds are fine.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 29, 2013, 7:30 AM
Post #9 of 14
(1587 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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I totally agree.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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mmook87
New User
Dec 4, 2013, 3:30 PM
Post #10 of 14
(1564 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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ISSUE RESOLVED.
Thanks everyone for your help and time.
I figured out that the problem was caused by severe corrosion where the two ground wires were attached to the underside of the truck.
I found and cleaned a new spot. Attached the wires and they now work normally.
Thanks again.
Mike
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 5, 2013, 4:50 AM
Post #11 of 14
(1557 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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I'll close this as solved. Any grounds you see when working on something take a look, rot proof them as they do cause whacked issues. Glad it's fixed,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 5, 2013, 5:07 AM
Post #12 of 14
(1551 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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I don't know what any of that had to do with the position of the pedal but if it's fixed, great.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 5, 2013, 6:31 AM
Post #13 of 14
(1546 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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Neither do I. Open it if think best as the problem really should/may return but it was mentioned those grounds were lousy -- T
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 5, 2013, 6:39 AM
Post #14 of 14
(1542 views)
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Re: 97 Chevy 1500 P/U 4.3L - brake light issue.
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Nah, I think he just totally had the symptoms wrong. That happens way too often around here.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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