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Turn Signal Activates Hazard Lights

CL
Cary Lawson
Sun, Jun 6, 2021 8:08 PM

The left turn signal activates the hazard lights.

My coach has been laid up for over a year and a half.
I got a lot of work done on other parts of it during covid but found this testing lights now to use it.
And yes I could have disrupted the wiring on some of my other work.

The right turn signal works properly.
The hazard switch works properly.
The parking light switch lights up all the lights properly.

The flasher unit was replaced 2 years ago with a newer style electronic one.

I would appreciate any advice on how to diagnose the problem.
In particular I would like to eliminate other possibilities to avoid disassembling the steering column if not needed.
Thanks!

--
Cary Lawson
1975 Glenbrook, 455, Rochester carb
Wellington, Ohio

The left turn signal activates the hazard lights. My coach has been laid up for over a year and a half. I got a lot of work done on other parts of it during covid but found this testing lights now to use it. And yes I could have disrupted the wiring on some of my other work. The right turn signal works properly. The hazard switch works properly. The parking light switch lights up all the lights properly. The flasher unit was replaced 2 years ago with a newer style electronic one. I would appreciate any advice on how to diagnose the problem. In particular I would like to eliminate other possibilities to avoid disassembling the steering column if not needed. Thanks! -- Cary Lawson 1975 Glenbrook, 455, Rochester carb Wellington, Ohio
JR
John R. Lebetski
Sun, Jun 6, 2021 8:32 PM

I don’t have a schematic up in front of me. But probably not the flasher as it works on right side. Have you exercised the flasher button vigorously
to be sure it is unlatching?  Good news is if turn signal switch broke, you hardly have to rip apart the column. Just pull wheel and depresser tool
the lock ring to get to switch assembly.

John Lebetski
Woodstock, IL
77 Eleganza II

I don’t have a schematic up in front of me. But probably not the flasher as it works on right side. Have you exercised the flasher button vigorously to be sure it is unlatching? Good news is if turn signal switch broke, you hardly have to rip apart the column. Just pull wheel and depresser tool the lock ring to get to switch assembly. -- John Lebetski Woodstock, IL 77 Eleganza II
ED
Ernest Dankert
Mon, Jun 7, 2021 2:43 AM

check your left rear bulb, I am betting a filament has sagged and shorting out the running lamp filament.

1977 Eleganza II
Ogden NY

check your left rear bulb, I am betting a filament has sagged and shorting out the running lamp filament. -- 1977 Eleganza II Ogden NY
JR
John R. Lebetski
Mon, Jun 7, 2021 4:08 PM

I thought about that one before I responded, but that would make running lights glow with left turn.  Would not light right turn.

John Lebetski
Woodstock, IL
77 Eleganza II

I thought about that one before I responded, but that would make running lights glow with left turn. Would not light right turn. -- John Lebetski Woodstock, IL 77 Eleganza II
CL
Cary Lawson
Mon, Jun 7, 2021 4:33 PM

Well thanks to everyone for the ideas!

I pulled the rear left bulb, it looked good. Tested the turn signal even without the rear bulb in, left turn signal still runs hazards.
Exercised the hazard switch to see if it was seized but appears not to be the problem.
Even tried moving the steering column to various positions to see if that would cause any changes.

Next step, I will be reading up on pulling the steering wheel and see what tools I can obtain from AutoZone.

--
Cary Lawson
1975 Glenbrook, 455, Rochester carb
Wellington, Ohio

Well thanks to everyone for the ideas! I pulled the rear left bulb, it looked good. Tested the turn signal even without the rear bulb in, left turn signal still runs hazards. Exercised the hazard switch to see if it was seized but appears not to be the problem. Even tried moving the steering column to various positions to see if that would cause any changes. Next step, I will be reading up on pulling the steering wheel and see what tools I can obtain from AutoZone. -- Cary Lawson 1975 Glenbrook, 455, Rochester carb Wellington, Ohio
MC
Matt Colie
Mon, Jun 7, 2021 11:05 PM

CLawson wrote on Mon, 07 June 2021 12:33

Well thanks to everyone for the ideas!

I pulled the rear left bulb, it looked good. Tested the turn signal even without the rear bulb in, left turn signal still runs hazards.
Exercised the hazard switch to see if it was seized but appears not to be the problem.
Even tried moving the steering column to various positions to see if that would cause any changes.

Next step, I will be reading up on pulling the steering wheel and see what tools I can obtain from AutoZone.

Cary,

I can't think of any place that cross connect could be except in that switch.
I have a steering wheel puller and a lock-plate depressor that you will need, but here to Wellington is a little long for a tools drop run.  I am
pretty sure that they will all fit in a USPS8.75$ box.  If you can't do better locally, get back to me.

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

CLawson wrote on Mon, 07 June 2021 12:33 > Well thanks to everyone for the ideas! > > I pulled the rear left bulb, it looked good. Tested the turn signal even without the rear bulb in, left turn signal still runs hazards. > Exercised the hazard switch to see if it was seized but appears not to be the problem. > Even tried moving the steering column to various positions to see if that would cause any changes. > > Next step, I will be reading up on pulling the steering wheel and see what tools I can obtain from AutoZone. Cary, I can't think of any place that cross connect could be except in that switch. I have a steering wheel puller and a lock-plate depressor that you will need, but here to Wellington is a little long for a tools drop run. I am pretty sure that they will all fit in a USPS8.75$ box. If you can't do better locally, get back to me. 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
KB
Ken Burton
Tue, Jun 8, 2021 5:05 AM

AutoZone loaner program has what you need.

Also Autozone stocks the switch for around $30.00

If you are not sure the switch is bad, Get a new one from and plug it in to the long flat  connector before you start to remove the wheel.  Try the
switch to see if it fixes your problem before mounting it in the steering column.

It is not a difficult job with the two loaner tools, A deep well socket for steering wheel nut, a couple of screw drivers, plus a pair of diagonal
wire cutting pliers.  Also about a 3 foot piece of nylon string and some electrical tape.  I have done is in the AZ parking lot in about 1/2 hour.
Figure double that time if you have not done it before.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

AutoZone loaner program has what you need. Also Autozone stocks the switch for around $30.00 If you are not sure the switch is bad, Get a new one from and plug it in to the long flat connector before you start to remove the wheel. Try the switch to see if it fixes your problem before mounting it in the steering column. It is not a difficult job with the two loaner tools, A deep well socket for steering wheel nut, a couple of screw drivers, plus a pair of diagonal wire cutting pliers. Also about a 3 foot piece of nylon string and some electrical tape. I have done is in the AZ parking lot in about 1/2 hour. Figure double that time if you have not done it before. -- Ken Burton - N9KB 76 Palm Beach Hebron, Indiana
BH
Bruce Hislop
Tue, Jun 8, 2021 10:56 AM

Now over at Facebook this question would have deteriorated into comments about you need to change the Blinker Fluid and other such nonsense.

Nice to have only serious answers.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

Now over at Facebook this question would have deteriorated into comments about you need to change the Blinker Fluid and other such nonsense. Nice to have only serious answers. -- Bruce Hislop ON Canada 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001 My Staff says I never listen to them, or something like that
CL
Cary Lawson
Thu, Jun 10, 2021 1:47 AM

I wanted to thank everyone for the great advice and support.
I bought the AutoZone replacement switch and borrowed their wheel puller and spring compression tools. The switch replacement went much easier than I
ever would have imagined.

Here are some notes from the experience that might be helpful for other mechanical ‘newbies’:

Ken Burton’s steps on thread “Turn signal replacement” was a great help:
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=362913&rid=5142&srch=turn+signal#msg_362913

I added these steps to Ken’s instructions:

  1. Disconnect engine battery first
  2. Mark steering wheel hub and column bolt position to align steering wheel when reinstalling
  3. After switch removed, adjust column tilt for greatest clearance through wiring channel
  4. Remove new switch connector (had to do it anyway), tape cabling to be as flat as possible, and pull just wires down, then attach original
    connector.

The new switch improved functionality but the left turn signal still ran the hazards.
With a known good switch I found the switch connector pin descriptions online. Also using the wire diagrams in the tech manual I was able to trace
each of the leads through the coach.

Pin M, Yellow wire to Left Rear Lamps, was the final culprit.
Ultimately I was able to trace the problem to left rear corner under the bed where the wiring harness ran through a series of 6-pin connectors, linked
with several 2-pin connectors, a tee, and doubled up wires at some connectors. With brittle-bunched-together-46-year-old wires a short was waiting to
happen. For now I clipped the yellow line that was continuing through the backwall channel to the passenger side and found that fixed the last issue.
Besides being very difficult to reach that area I couldn't see why the Yellow Driver side signal wire was needed on the passenger side anyway.
Rewiring the back under the bed will be left as a future major endeavor.

Any way that’s what I did.
Cary

Connector pin-outs:
The new AutoZone SW326 switch wire colors are different from OEM original as well as the connector didn’t fit (too long) nor align with chassis
connector. Unfortunately an adapter wasn’t included in the box.

Found switch wire functions in this YouTube video:
https://www.youtube.com/watch?v=ZmRR0AeZspk

Connectors were molded with pin positions labeled A through P.

AutoZone SW326 wiring (other switches most likely similar):
Posit’n-Color---Function--------------------------Notes
G-------Black---Ground for horn
H-------Lt Blue-Sends Pwr to Lt Frt turn lamps---Lt blue wire also drives dash Lt turn indicator
J-------Blue----Sends Pwr to Rt Frt turn lamps---Blue wire also drives dash Rt turn indicator
K-------Brown---12V Pwr for Hazard function------Should send pwr whether ignition on or not
L-------Purple--12V Pwr for the Turn functions---Should send pwr when ignition on
M-------Yellow--Sends Pwr to Lt Rear lamps-------Yellow and Green also Pwr Brake Lts
N-------Green---Sends Pwr to Rt Rear lamps-------Yellow and Green also Pwr Brake Lts
P-------White---12V Pwr from Brake switch--------Enables turn signals when braking

Turn Switch Testing:
Disconnect connector to only test switch
Put 12V Pwr to the Purple wire (L)
LT Turn lever position should only put pwr to Lt Blue(H) and Yellow(M) wires
RT Turn lever position should only put pwr to Green(N) and Blue(J) wires
Middle lever position should not send pwr to any wire
Put 12V Pwr to the Brown wire (K)
Hazard button should send pwr to (H, M, N, J)
Only test for continuity from Black (G) to horn contact point on switch

--
Cary Lawson
1975 Glenbrook, 455, Rochester carb
Wellington, Ohio

I wanted to thank everyone for the great advice and support. I bought the AutoZone replacement switch and borrowed their wheel puller and spring compression tools. The switch replacement went much easier than I ever would have imagined. Here are some notes from the experience that might be helpful for other mechanical ‘newbies’: Ken Burton’s steps on thread “Turn signal replacement” was a great help: http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=362913&rid=5142&srch=turn+signal#msg_362913 I added these steps to Ken’s instructions: 1. Disconnect engine battery first 2. Mark steering wheel hub and column bolt position to align steering wheel when reinstalling 3. After switch removed, adjust column tilt for greatest clearance through wiring channel 4. Remove new switch connector (had to do it anyway), tape cabling to be as flat as possible, and pull just wires down, then attach original connector. The new switch improved functionality but the left turn signal still ran the hazards. With a known good switch I found the switch connector pin descriptions online. Also using the wire diagrams in the tech manual I was able to trace each of the leads through the coach. Pin M, Yellow wire to Left Rear Lamps, was the final culprit. Ultimately I was able to trace the problem to left rear corner under the bed where the wiring harness ran through a series of 6-pin connectors, linked with several 2-pin connectors, a tee, and doubled up wires at some connectors. With brittle-bunched-together-46-year-old wires a short was waiting to happen. For now I clipped the yellow line that was continuing through the backwall channel to the passenger side and found that fixed the last issue. Besides being very difficult to reach that area I couldn't see why the Yellow Driver side signal wire was needed on the passenger side anyway. Rewiring the back under the bed will be left as a future major endeavor. Any way that’s what I did. Cary Connector pin-outs: The new AutoZone SW326 switch wire colors are different from OEM original as well as the connector didn’t fit (too long) nor align with chassis connector. Unfortunately an adapter wasn’t included in the box. Found switch wire functions in this YouTube video: https://www.youtube.com/watch?v=ZmRR0AeZspk Connectors were molded with pin positions labeled A through P. AutoZone SW326 wiring (other switches most likely similar): Posit’n-Color---Function--------------------------Notes G-------Black---Ground for horn H-------Lt Blue-Sends Pwr to Lt Frt turn lamps---Lt blue wire also drives dash Lt turn indicator J-------Blue----Sends Pwr to Rt Frt turn lamps---Blue wire also drives dash Rt turn indicator K-------Brown---12V Pwr for Hazard function------Should send pwr whether ignition on or not L-------Purple--12V Pwr for the Turn functions---Should send pwr when ignition on M-------Yellow--Sends Pwr to Lt Rear lamps-------Yellow and Green also Pwr Brake Lts N-------Green---Sends Pwr to Rt Rear lamps-------Yellow and Green also Pwr Brake Lts P-------White---12V Pwr from Brake switch--------Enables turn signals when braking Turn Switch Testing: Disconnect connector to only test switch Put 12V Pwr to the Purple wire (L) LT Turn lever position should only put pwr to Lt Blue(H) and Yellow(M) wires RT Turn lever position should only put pwr to Green(N) and Blue(J) wires Middle lever position should not send pwr to any wire Put 12V Pwr to the Brown wire (K) Hazard button should send pwr to (H, M, N, J) Only test for continuity from Black (G) to horn contact point on switch -- Cary Lawson 1975 Glenbrook, 455, Rochester carb Wellington, Ohio
KB
Ken Burton
Fri, Jun 11, 2021 3:41 PM

RF_Burns wrote on Tue, 08 June 2021 05:56

Now over at Facebook this question would have deteriorated into comments about you need to change the Blinker Fluid and other such nonsense.

Nice to have only serious answers.

Ah yes,  I forgot to suggest he check and maybe change that.  I need to do that on my next oil change.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

RF_Burns wrote on Tue, 08 June 2021 05:56 > Now over at Facebook this question would have deteriorated into comments about you need to change the Blinker Fluid and other such nonsense. > > Nice to have only serious answers. Ah yes, I forgot to suggest he check and maybe change that. I need to do that on my next oil change. -- Ken Burton - N9KB 76 Palm Beach Hebron, Indiana