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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: 1980 gold on November 10, 2011, 04:23:10 pm

Title: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 10, 2011, 04:23:10 pm

my friends truck but i'm trying to help. it's an electrical question so here goes. p/s rear blinker and brakelight don't work. tail lights both work fine. new bulbs new flasher hazards work. if you put on the left turn signal both left and right rear blinkers flash. i cleaned up the chassis ground and added a washer the ground is connected to both tailights and license plate lamp harness. should they be grounded indivdually? although they worked before like this. only the left rear brake light works BUT if i switch the tailight circuit boards ( plug the rt one into the left harness and vice versa) the p/s blinker will now work and the brake lights will now work on the right side can i assume that is the circuit board? sorry if anyone got a headache from reading this

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: Captkaos on November 10, 2011, 04:24:48 pm

Check the front bulbs.

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 10, 2011, 04:42:52 pm

thanks we'll do one correction when you use the left blinker all 4 blinkers go on (front and rear)

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 10, 2011, 05:12:41 pm

ok so i got all 4 to come off at once its weird i pulled all 4 front bulbs put them back i have front and rear d/s blinkers and just front p/s blinkers still no p/s rear blinker or brake light. circuit board?  oh also when i turn on the headlights i lose the d/s front blinker

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: Captkaos on November 10, 2011, 08:29:59 pm

Wait, your talking about a 88 C/K truck...

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 10, 2011, 08:49:29 pm

yes

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: zieg85 on November 10, 2011, 10:50:15 pm

I had a similar experience with a 1995 C1500 where the problem seemed to move around.  What I did was to take apart the rear lighting and cleaning/greasing back the connections which were intermittent.  The connections were arcing at times, I found the problem at night by accident.

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 11, 2011, 11:22:45 pm

hey thanks what it ended up being was the rear bulbs are mountedin their socket in what looks like a printed circuit sandwiched between  layers of plastic i switched the left one that was working to the right side and it worked for both signal and blinker on that side so we ordered one as our salvage yards on long island almost never have anything below 95

Title: Re: 88 gmc 1500 sierra tail light trouble
Post by: 1980 gold on November 18, 2011, 09:33:57 pm

so we put in rt side circuit board everything works now blinkers brake lights tail lights and i know what to do on next job