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C3 Electrical

right turn signal problem (1/6)
 9/4/18 5:35pm
island vette
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, - Canada

Vette(s):
1978 Silver Anniversary


Joined: 9/4/2018
Posts: 5

Hi to everyone.  I'm new to this forum.  I recently purchased a 1978 Silver Anniversary Corvette, which has recently developed an issue with the right front turn signal.  I noticed that although the blinker was operating at normal speed, the indicator lamp was not operating on the instrument panel.  After investigating, found the right rear signal operating normally, but no front signal or illumination.  Replaced 1157 signal bulb with two new bulbs, and the flasher behind the glove box, which didn't help.  Replaced bulb in side marker/signal lamp as well.

I then checked with a test light the contacts in the rectangular plug which goes into the front lamp socket harness.  The contact on the side for the signals showed no power with the signal on.  When the parking lights were turned on, the contact then showed a steady, but dim glow, with signals on or off.  The side for the parking light was bright.  I then probed the blue wire for the signal light with the test light before it enters the plug, and there was still no indication of power when parking lights off, and dull glow when parking lights were on.  When parking lights on, right dash indicator arrow glows dull as well.  I assume at this point I will need to open the sheath around the harness along the front of the engine compartment and go from there to look for a ground or wiring issue, or could it be the signal switch itself?  Left side turn signal and running lamps working normally.

I know it's a long explanation, but thought is would simplify the diagnostic process.  Thanks, Gary
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Re: right turn signal problem (2/6)
 9/4/18 9:55pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 19603

Do the hazard lights work on all 4 corners?
Do the brake lights work properly? Also...by chance does the right front sig come on when you mash the brake pedal?
From what I read, you may have a backfeed to ground on the front signal circuit. Unfortunately....it really appears to be a problem with the turn signal switch. You have NO front sig, and NO indicator light in the dash, but the right rear turn sig IS working properly, correct? I would suggest doing your testing at the turn sig connector, on the steering column under the dash. If the signal is not getting out of the turn sig switch, it's not gunna get to the socket at the front. It would be best to start from the source, and not start ripping into the front harness until you determine if the signal is even coming out of the switch....imho. Thumbs Up


btw...if you need the wiring diagram(s) for your car, you can view and/or download them from my web page HERE.


______________
Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Re: right turn signal problem (3/6)
 9/5/18 4:53pm
island vette
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, - Canada

Vette(s):
1978 Silver Anniversary


Joined: 9/4/2018
Posts: 5

Thanks for the input.  Everything else seems to work as expected, so I will begin looking into the signal switch connector to check the circuit there.
Re: right turn signal problem (4/6)
 9/5/18 6:03pm
island vette
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, - Canada

Vette(s):
1978 Silver Anniversary


Joined: 9/4/2018
Posts: 5

I've checked the right turn signal output from the dark blue wire at the steering column connector, and have a strong flashing light from my test lamp on either side of the connector but, when either left or right signal engaged.  Also a dim glow from test light when signals disengaged.  However, when I probe the left signal contact, I am also getting a flashing signal, but only when left signal engaged. when the signal switch is turned off, test light turns off as well.   It appears there must be an internal short in the signal switch itself?
Re: right turn signal problem located (5/6)
 9/6/18 3:32am
island vette
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, - Canada

Vette(s):
1978 Silver Anniversary


Joined: 9/4/2018
Posts: 5

I have inadvertently discovered the signal issue with my C3.  It is a loose connection from the dark blue wire at the "harmonica."  The connector had been hanging under the instrument panel, and I noticed the bracket for it at the steering column.  Once I installed the harmonica into the bracket, the turn signal indicator light came on.  Upon checking the front of the car, the side marker was flashing, but still no signal light.  After cleaning and reconnecting the connector to the signal lamp harness, the bulb began to operate normally.  So there were two issues with the turn signal wiring.  I will need to open up the harness and fix the wiring issue, as the turn signals operate intermittently when the wire is wiggled.  Just happy I don't have to replace the signal switch Smile

Re: right turn signal problem (6/6)
 9/6/18 2:02pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
Posts: 19603

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______________
Joel Adams
C3VR Lifetime Member #56    

My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"