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My turn signals went from great to nonexistent over night on my 77.
Checked the fuse and power to the fuse. I have power. Replaced turn signal switch, Checked the bulbs, Replaced the flasher and still have nothing. And, of course, no backup lights. WTF?
Any of you electrical guys out there have any ideas where to look next?
Wow! Your just throwing parts at it like they are free!
there not.
Don't you own a test light?
How about the genuine G.M. 1977 Corvette Electrical Trouble Shooting Manual?
if not. Get both.
from page 12, 77 Electrical Trouble Shooting Manual.
power from DIR. SIG. BK UP fuse. Pink/white wire to flasher. Do you have power at flasher. The one behind the map pocket. NOT the one on the fuse panel.
do you have power out of flasher? Purple wire.
power on Purple wire on both sides of harmonica connector?
In my experience issues like yours are many times caused by bad grounds. Years ago I chased a similar problem and could not find the bad ground. Ended up making a ground jumper for each turn signal in the housing and grounded the jumper to the housing. Solved the problem.
My turn signals went from great to nonexistent over night on my 77.
Checked the fuse and power to the fuse. I have power. Replaced turn signal switch, Checked the bulbs, Replaced the flasher and still have nothing. And, of course, no backup lights. WTF?
Any of you electrical guys out there have any ideas where to look next?
The back up lights at the same time causes me to think it's a common ground as 66Ray commented. I think the next place to look is at a wiring schematic for '77 to see if/how the reverse lights are tied in with the turn signals. Just out of curiosity, do your hazard flashers work? How about the side marker running lights and brake lights? Is this isolated to only the rear of the car or front lighting too?
Last edited by barkingrats; Mar 11, 2023 at 08:00 AM.
Thanks for the responses. 67-72, hazard flashers do not work. Front and rear turn signals do not work. Park lights and brake lights do work. Backup lights do not work. I have no power on the purple wire at the harmonica connector but power at the fuse block. The horn does work which goes through the harmonica connector.
Back up lights and turn signals run off the same fuse. So, find your flasher behind the map pocket, Rh dash. Lower right corner, very close to the RH lower courtesy light. Do you have power at this flasher? If no, check to see if you have power at the reverse switch. Not clear on your transmission so I won't tell you how to find it.
perhaps you have power to the fuse but not getting through the fuse box. Like bad terminals preventing power getting through or a broken wire on the back side of the fuse box. Try cleaning the metal clips that hold the fuse first. Do this with battery disconnected. Then put in a new fuse with a bit of dielectric grease just because.
On a Late 1977 there are 2 pink/white stripe wires at the flasher relay a #14 gauge and a #20 gauge.
Interesting thing, on a Late 1977 the #20 gauge runs back to a connector near the shiftier.
On a A/T car that connector plugs into the neutral safety/backup light switch.
On a manual transmission car that connector plugs into a completely separate harness and the wire color changes to #20 gauge pink/blk wire leading to the backup light switch.
So, the turn signal flasher relay you want is a #224.
You may also find a old cap installed at the flasher relay.
Late 1977...
On a Late 1977 there are 2 pink/white stripe wires at the flasher relay a #14 gauge and a #20 gauge.
Interesting thing, on a Late 1977 the #20 gauge runs back to a connector near the shiftier.
On a A/T car that connector plugs into the neutral safety/backup light switch.
On a manual transmission car that connector plugs into a completely separate harness and the wire color changes to #20 gauge pink/blk wire leading to the backup light switch.
So, the turn signal flasher relay you want is a #224.
You may also find a old cap installed at the flasher relay.
Late 1977...
That is the flasher that I have with the 2 pink wires,bmotojoe. I'll check the wire that goes to the shifter area.
Thanks for the chart, peterbilt. I'll assume the wires are correct since the turn signals worked for 2 years. But I will check them.
The #14 gauge pink/white stripe wire is the wire from fuse panel.
The #20 gauge pink/white stripe wire goes to the connector at the shift area or backup light switch portion of the neutral safety switch if A/T.
If there is a fault in the wire someplace between the relay and connector at shift area, that would only effect the backup lights only.
Turn signal problem
