87GT Stop Lights not working (Page 1/1)
Dennis LaGrua JUN 15, 05:07 PM
Not getting any power to the stop lights. Checked fuse that was OK. Seems like a simple circuit but can't find the problem. Might be the stop light switch but on the brake pedal there are two switches. The one underneath is a black case switch while the one on the top above is cream colored and probably for the cruise or torque converter lock up. At this point I believe the switch may be the problem. Anyone have any ideas how to check and narrow this down?

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

fierosound JUN 15, 05:44 PM
The lower switch should have a connector with 12V Orange, Light Blue, White wires.
LT Blue wire should have 12V when brake is pressed and switch plunger "comes out".
If you have power there, then you must have lost Ground on the Stop Lights circuit.





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[This message has been edited by fierosound (edited 06-15-2020).]

Dennis LaGrua JUN 15, 06:12 PM
Thanks much for the info and the help. Found a switch in my stock. Now if you could give me a hint on how to get that switch loose from the locking clip that would be most appreciated. I know that when you install them they just push in but its only a one way catch.
Don't believe I could have lost the ground as the two filament bulb (stop + tail light) uses the same black wire ground and the tail lights work. Betting on a bad switch. We will see.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

theogre JUN 16, 03:33 PM
Try turning them to remove/install. May need to remove/rotate other switch to clear the "bad" one.

Think they have normal treads but the "nut" clicks to adjust so don't have to unplug the wires to set them.
Don't have one to look now.

Search in any FSM.

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Dennis LaGrua JUN 16, 03:47 PM
OK men many thanks for the great info. This was a hard one, well not really!!! We had an extra switch in the shop and tried that. It was the friggin switch that broke apart internally. Could you believe that happened in a car with 66K miles!! As for changing the switch; with a few twists it just pulls out then you just press the new switch into place and it seems to hold. If that doesn't work, new retainers are available and some lever switch nuts will fit the threads on the switch . The hardest part was pulling the two connectors. Had to use a small flat blade screwdriver to depress the locking tab and pry them loose. I can only guess that this problem has been going on for a while so I suggest to all owners to periodically check to see if your brake lights work. Needless to say, it is quite dangerous driving without them. I caught mine when I went to LED light upgrades otherwise who knows when I would have caught the problem.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

fierosound JUN 17, 12:00 PM

quote
Originally posted by Dennis LaGrua:

OK men many thanks for the great info. This was a hard one, well not really!!! We had an extra switch in the shop and tried that. It was the friggin switch that broke apart internally. Could you believe that happened in a car with 66K miles!! As for changing the switch; with a few twists it just pulls out then you just press the new switch into place and it seems to hold.