Sir, as you know the turn and brake lights are the same bright filament in the bulb and the park lights are a separate dim circuit on a different filament on the bulb. Look at the bulbs as the mounting bayonet style pins are offset and only go 1 way right. I have done them wrong with a little force. Is the brake light switch working? It is on the top of brake pedal bracket. The turn signals are powered all the time and the switch selects right or left. A tidbit of info Is the park lights will work without a good ground but the brake and turn signals won’t. They will try to ground thru the dim parking light and will cut it off and on like it is blinking but the bright side should be coming on when the dim one goes out with a good ground. Sometimes the later GMC taillights are installed and they require a ground for each bulb.

LED lamps are polarity sensitive. Maybe that's your problem, Shan.

Haven't seen you on here in quite a while. Still using the XD Star wheels?
I bought a set in chrome for my coach.

D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com

________________________________
From: Shan Rose
Sent: Tuesday, March 30, 2021 21:00
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Now what... still no rear turns or brake lights

Its all new guts, including brake switches. Also running Led bulbs,, which worked before
the rig sat. Is there a common ground in the body harness? My rig is number 1885 off the assemblyline. So its a 73. I doubt both LED bulbs would go
tits up at once...C Boyd wrote on Tue, 30 March 2021 16:45
> Sir, as you know the turn and brake lights are the same bright filament in the bulb and the park lights are a separate dim circuit on a different
> filament on the bulb. Look at the bulbs as the mounting bayonet style pins are offset and only go 1 way right. I have done them wrong with a
> little force. Is the brake light switch working? It is on the top of brake pedal bracket. The turn signals are powered all the time and the switch
> selects right or left. A tidbit of info Is the park lights will work without a good ground but the brake and turn signals won’t. They will try
> to ground thru the dim parking light and will cut it off and on like it is blinking but the bright side should be coming on when the dim one goes
> out with a good ground. Sometimes the later GMC taillights are installed and they require a ground for each bulb.

73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA

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Well it must be grounding out somewhere. I'm hoping just a connection in the body harness as everything else works, where's the junctio from the dash to body harness?

Sir, you said you changed the turn signal switch? The last few I got had the wrong plug on the switch where it plugs to the body harness on the outside of the steering column. Maybe check to see if it is connected straight and tight. If it is check to see if your brake light switch is getting 12 v , both sides when pedal is pressed. If you drop the bottom cover it is easy to see.







Duce Apocalypse wrote on Sat, 03 April 2021 13:54

Well it must be grounding out somewhere. I'm hoping just a connection in the body harness as everything else works, where's the junctio from the dash to body harness?