GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.
Home » Public Forums » GMCnet » Brake lights wont work...
Brake lights wont work... [message #362378] Sun, 14 February 2021 09:41 Go to next message
Duce Apocalypse is currently offline  Duce Apocalypse   United States
Messages: 824
Registered: May 2009
Location: Los angeles
Karma: 0
Senior Member
Any ideas? In thinking the BOO switch

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

Report message to a moderator

Re: Brake lights wont work... [message #362381 is a reply to message #362378] Sun, 14 February 2021 10:54 Go to previous messageGo to next message
Duce Apocalypse is currently offline  Duce Apocalypse   United States
Messages: 824
Registered: May 2009
Location: Los angeles
Karma: 0
Senior Member
Duce Apocalypse wrote on Sun, 14 February 2021 07:41
Any ideas? In thinking the BOO switch
Actually the rear signals dont work either. Bad chassis ground??

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

Report message to a moderator

Re: Brake lights wont work... [message #362383 is a reply to message #362381] Sun, 14 February 2021 11:30 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   Canada
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
Duce Apocalypse wrote on Sun, 14 February 2021 11:54
Duce Apocalypse wrote on Sun, 14 February 2021 07:41
Any ideas? In thinking the BOO switch
Actually the rear signals dont work either. Bad chassis ground??
Duce,

If you mean the rear turn signals, they are the same filament as the brake lights.....

If it were just a bad chassis ground, things back there would work badly or strangely because the light assemble would be grounded through the marker light filaments to the front frame.

I suggest that you get out the chassis wiring diagrams and carefully diagnose the system.
All of those signals (brake and turn) go through the turn signal switch and that has a major junction down on the steering column. If things aren't good there, they won't be good any where.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

Report message to a moderator

Re: Brake lights wont work... [message #362384 is a reply to message #362378] Sun, 14 February 2021 13:07 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
What other rear lights are out? Tail, clearance, License plate light? Turn signals are the same filaments as brake lights. I assume that you checked the fuse.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

Report message to a moderator

Re: Brake lights wont work... [message #362396 is a reply to message #362378] Sun, 14 February 2021 18:42 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
Exercise the 4 way flasher switch. It has to go through there to get to the rear.

John Lebetski
Woodstock, IL
77 Eleganza II

Report message to a moderator

Re: Brake lights wont work... [message #362397 is a reply to message #362384] Sun, 14 February 2021 18:42 Go to previous messageGo to next message
Duce Apocalypse is currently offline  Duce Apocalypse   United States
Messages: 824
Registered: May 2009
Location: Los angeles
Karma: 0
Senior Member
Clearance lights still work wheres the fuse looking over the wiring diagram cant find it :-/

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

Report message to a moderator

Re: Brake lights wont work... [message #362399 is a reply to message #362397] Mon, 15 February 2021 00:42 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
Look at the wiring diagram on the left side for "Directional Signal Haz and stop". It shows a 20 amp fuse feeding all of that. The fuse is located inside the glove compartmment behind a steel plate held in with one screw.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Updated on: Mon, 15 February 2021 11:36]

Report message to a moderator

Re: Brake lights wont work... [message #362404 is a reply to message #362399] Mon, 15 February 2021 08:30 Go to previous message
Jp Benson is currently offline  Jp Benson   United States
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
Senior Member
There's a Packard 56 connector on the drivers side where the dash meets the side trim panel. I've had loose brake light connections there. It's also a good place to diagnose whether the problem is upstream or downstream in the circuit. That is if you can get to it.

JP

Report message to a moderator

Previous Topic: Heater Blower Motor
Next Topic: electro level system
Goto Forum:
  


Current Time: Thu Oct 03 03:40:36 CDT 2024

Total time taken to generate the page: 0.01462 seconds
.:: Contact :: Home ::.

Powered by: FUDforum 3.1.1.
Copyright ©2001-2021 FUDforum Bulletin Board Software