No Rear Left Brake Light

[CREATIVERS]

My left rear brake light does not work. Nor does it work with 4-way flashers (all other lights do flash). But it DOES work as a left turn signal. That
indicates that the problem is up-front, right? Any clues what to look for? Does that circuit run through a fuse? I think I tested continuity, zero
ohms, across all fuses. But then again, it seemed that the entire right side of the fuse box had no juice. Maybe that's the problem? Is there a
picture of my fuse box somewhere that I could read and understand what each fuse does? I saw an electrical diagram on
http://www.bdub.net/wirediagrams/X7321A-Electrical-Diagram.pdf, but I don't understand that. And not sure what might be different on my '73 23'. For
that matter, I cannot even find my flasher. I hear it, but can't find it.
Thanks for any clues or guesses what to look for.
--
Paul & Carolynn Lynnwood WA
'73 23' I don't know the model. Mid-bath.
Presently gutted. Installed One-Ton FrontEnd.

 

[terry1]

Not a fuse, not the flasher. The difference between the stuff that works and the light that doesn't occurs in the turn signal switch or in the light
bulb socket or the ground for that socket. If the proper filament is lighting with the turn signal (the bright one), then the problem is a sunken
contact in the turn signal switch. The circuit drew too much power for too long a time, and the contact for normal operation got hot and shrank away
from the other contact. Probably related to trailer wiring and staying on the brake pedal for an extended period of time with the extra trailer load
on the circuit.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[Matt Colie]

> My left rear brake light does not work. Nor does it work with 4-way flashers (all other lights do flash). But it DOES work as a left turn signal.
> That indicates that the problem is up-front, right? Any clues what to look for? Does that circuit run through a fuse? I think I tested continuity,
> zero ohms, across all fuses. But then again, it seemed that the entire right side of the fuse box had no juice. Maybe that's the problem? Is there a
> picture of my fuse box somewhere that I could read and understand what each fuse does? I saw an electrical diagram on
> http://www.bdub.net/wirediagrams/X7321A-Electrical-Diagram.pdf, but I don't understand that. And not sure what might be different on my '73 23'. For
> that matter, I cannot even find my flasher. I hear it, but can't find it.
> Thanks for any clues or guesses what to look for.

Paul,

Yes, the problem is up front and it is not the flasher. Find that later.

If it works on turn, but not on brake or 4-way, it pretty much has to be a problem in the turn signal switch.

Your 73-23 chassis electric is like all the others until the change to HEI, and that is not much.

I expect your problem is the turn signal switch. These are a common failure. Until recently, it was such a common part that you could pick off a
hook at a store front parts store.

Replacing it is not difficult, but it is a major league PITA. You will need a steering wheel puller and the GM switch plate tool. Fortunately, many
of the car parts store have those tools available to loan. Find one of those and order the switch there.

Have a string ready. The connector is down the column. Tie or tape the string to it and then you can reverse that to get the new connector into the
column.

Good Luck

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

 

[CREATIVERS]

It sounds like it may be time to change the entire steering shaft to a tilt shaft. Except I am not finding one "plug-and-play", ready to install. And
not looking forward to converting an Eldorado column.
But I think you guys are saying that after I resolve my turn signal switch, I still have another problem. And that might be some direct short
somewhere? In fact, I believe all was working until I tried to wire up my boat trailer. But my boat trailer has working LED tail lights, and I've been
pulling it behind my van for years, with no issues. So I will try to narrow that down as well.
Thanks so much.
--
Paul & Carolynn Lynnwood WA
'73 23' I don't know the model. Mid-bath.
Presently gutted. Installed One-Ton FrontEnd.

 

[richard h staples]

Paul,
FWIW, I'd double check the grounding of that left Rr lamp, especially since you say the coach was gutted for restoration. From the diagram, you might
check the license light and left Rr side marker lamp as a test, since they appear to share a ground connection with the left tail/stop/turn lamp.
Double filament bulbs and lamps mounted in fiberglass can do strange things. HTH.
Rick Staples
--
Rick Staples, '75 Eleganza, Johnstown, CO

"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien

 

[Ken B]

1. Remove the offending bulb.
2. Attach one meter lead to the ground terminal inside the generator cabinet. It is a big vertical bolt mounted through rear floor. (DO NOT use the
rear bumper as a ground test point.)
3. Probe the outer circular bulb socket with the other lead looking for zero ohms.
4. Turn on left turn signal and probe the two bulb contacts, one at a time.

While Probing each one of the contacts with a test light (preferred) or your volt meter, you should see it switching between +12 and 0 volts.

If it is not switching on one of the bulb contacts you have a problem up front.

If it comes down to it and you need to replace the the turn signal switch, it is not a difficult jog. You need to remove the steering wheel. You can
borrow the removal tools from AutoZone or stop me at the next GMCMI rally and borrow mine.

Before starting the job you need to unplug the switch connector on the bottom of the steering column and verify that the new one that you bought is
EXACTLY same connector type. I would verify that it really plugs into the socket BEFORE proceeding to remove the old switch. There are two different
connector types and they look the same. One has slightly wider on the terminal spacing. There also are two different switch types. One has extra
contacts for cornering lights, the other does not. YOU CAN USE EITHER SWITCH TYPE. If you have the cornering type the additional contacts will just
not be used and the switch is cheaper.

You should be able to do the job in under 1 hour. I have done it in the AutoZone parking lot. Prior to removing the old one, cut the connector off.
Attach (tape) a heavy string to the cable at the bottom and pull the switch out of the top. You now have a string to attach the new cable to and pull
the wires and connector back through the steering column. One other thing. Tape the connector flat against the wires prior to pulling them through
the steering column.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[CREATIVERS]

Ken,
Just want to let you know I saw your message here.
Thank you for the thorough explanations. Although actually, I am in discussion with Jim K about getting a tilt column from a donor coach, hoping I can
see the dash better than through my straight column. So I am looking at replacing the entire column.
But yes I do still need to check things out in the back, since there was probably a short that caused the problem in first place. Although I suspect
it happened when I tried to connect my boat. So I also intend to replace the trailer connector as well.
Paul
--
Paul & Carolynn Lynnwood WA
'73 23' I don't know the model. Mid-bath.
Presently gutted. Installed One-Ton FrontEnd.