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Dave Nova
Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 19451
Experience:  ASE Master Certification. GM World Class Certification
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Garvin 1991 GMC ***** ***** brake light issue Tail lights

Customer Question

Customer: Garvin 1991 GMC ***** ***** brake light issue Tail lights and Emergency flashers are ok no Brake lights Bulbs are good how do I check the switch? I have unpluged the wire and connected the 2 connections still no brake lights
JA: Thanks. Can you give me any more details about your issue?
Customer: What does the switch do Ground or supply power?
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Customer: no not now no time thanks though
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Submitted: 1 year ago.
Category: GM
Customer: replied 1 year ago.
Please reply via text also i will be out in shop for afternoon
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Dave Nova replied 1 year ago.

Start by testing for voltage on the orange wire at the switch. If you have voltage there and jumping the orange and white wires together does not make the brake lights come on then the problem is likely in the turn signal switch. Power goes from the brake switch, through the turn signal switch and then to the rear bulbs. (turn and brake uses same bulb filament at the rear) Since the turn signals work we know that the bulbs and wiring from the turn signal switch are okay.

Customer: replied 1 year ago.
I have no orange wire only grey and grey and black are attached to the plug on the switch, The switch has 2 sets of prongs but only one has a connector to it. Those are the grey and grey with black strip. I did jump these 2 together and have no brake lights. Whats next?
Expert:  Dave Nova replied 1 year ago.

These other wires may be for TCC unlock signal. The brake light wires are definitely Orange and White. Look around under the dash to see if the connector is unplugged from the switch.

Customer: replied 1 year ago.
Found the other plug hiding above switch plunged in and brake lights work! Thanks for the help.
Expert:  Dave Nova replied 1 year ago.

You are very welcome. Glad I could help.