1970 Chevelle SS turn signals both flash when parking / head lights when making a turn.

[mike1369]

Had this problem and followed a lot of technical suggestions on how to repair mostly grounding being the problem. After spending many hours checking ground connections at all lights could not find any bad grounds. We did find that the instrument cluster was powered through a Mylar Circuit Card Assy (CCA) on Chevelles. Very bad design by Chevrolet. The card is very flimsy in design and most are the original equipment and over the years become brittle and some of the runs start to separated or oxidize causing failure of instruments or intermittent failures making it hard to troubleshoot. The other issue is the main wire connector that plugs into the CCA , the Mylar connector is very bad design since the CCA runs have to be lined up with the main wire harness connector. The connector has to be pushed into the opening in the instrument metal cluster can, if not properly seated lots of problems electrically can occur. Back to my issue with turn signal's flashing, after many hours troubleshooting this issue I found that there had to be a common point that head lights and turn signals share and it was on the CCA. The bulbs had to share the same ground on the CCA, in order to find this I had to trace out each of the runs on the CCA and make my own schematic (which none of the GM drawings show). The final finding of the problem was the main wiring connector had not been seated completely and was causing the problem, by applying pressure with my hand was able to reseat and correct the issue. Just a side note we did replace the old CCA because it had some very badly damaged runs from age causing the Amp gauge not to work and some of the instrument lights. I would recommend if your car has the original CCA you might want to replace it not a real easy job. Also check to make sure the grounds to instrument panel are in good contact condition. I have attached a copy of the instrument CCA schematic hope this information will help anyone that is experiencing this problem or other instrument problems.

 

[kmakar]

Great explanation. Nicely done.

 

[DJ’s Garage]

Had this problem and followed a lot of technical suggestions on how to repair mostly grounding being the problem. After spending many hours checking ground connections at all lights could not find any bad grounds. We did find that the instrument cluster was powered through a Mylar Circuit Card Assy (CCA) on Chevelles. Very bad design by Chevrolet. The card is very flimsy in design and most are the original equipment and over the years become brittle and some of the runs start to separated or oxidize causing failure of instruments or intermittent failures making it hard to troubleshoot. The other issue is the main wire connector that plugs into the CCA , the Mylar connector is very bad design since the CCA runs have to be lined up with the main wire harness connector. The connector has to be pushed into the opening in the instrument metal cluster can, if not properly seated lots of problems electrically can occur. Back to my issue with turn signal's flashing, after many hours troubleshooting this issue I found that there had to be a common point that head lights and turn signals share and it was on the CCA. The bulbs had to share the same ground on the CCA, in order to find this I had to trace out each of the runs on the CCA and make my own schematic (which none of the GM drawings show). The final finding of the problem was the main wiring connector had not been seated completely and was causing the problem, by applying pressure with my hand was able to reseat and correct the issue. Just a side note we did replace the old CCA because it had some very badly damaged runs from age causing the Amp gauge not to work and some of the instrument lights. I would recommend if your car has the original CCA you might want to replace it not a real easy job. Also check to make sure the grounds to instrument panel are in good contact condition. I have attached a copy of the instrument CCA schematic hope this information will help anyone that is experiencing this problem or other instrument problems.

Having a similar issue on my 70. Everything in the cluster is new except the speedo and tach. Solved my lighting issue by adding an additional ground to the rear of metal cluster ‘fish’ to the body. However my turn signals on the cluster aren’t lighting up when the front/rear turn signals are flashing. Gonna try unplugging the cluster and plugging back in to see if I have the same issue. Thank You.

 

[Nashville Cat]

Not a solution for a "rare original" car, but Dakota Digital dashes are incredibly nice and put the guages up in the dash.
I put one in my 67 and am getting one for the 68 Camaro.

 

[DJ’s Garage]

I

Not a solution for a "rare original" car, but Dakota Digital dashes are incredibly nice and put the guages up in the dash.
I put one in my 67 and am getting one for the 68 Camaro.

Im not much on distal dashes. Actually I’m not much on technology either, probably why I haven’t owned a tv or computer in more than a decade.

 

[Nashville Cat]

Have you seen them ? They aren't "digital". That's just the name of the company.

 

[DJ’s Garage]

Have you seen them ? They aren't "digital". That's just the name of the company.

View attachment 39429

What are the rectangle boxes at the bottom, are those digital?

 

[Nashville Cat]

What are the rectangle boxes at the bottom, are those digital?

If you can't afford them it's ok

 

[Nashville Cat]

68 Camaro

 

[DJ’s Garage]

2 years ago we went to look at new Mustangs for my wife, turns out the don’t have a dash anymore, just 2 rectangle screens, one for the gauges and one for HVAC & Stereo system. Ended up getting something a few years older that actually had a gauge “looking” dash. A Mach 1

 

[DJ’s Garage]

If you can't afford them it's ok

Has nothing to do with affording, I prefer analog. If I couldn’t afford a dash, I’d just sell one of my 13 vehicles.

 

[Nashville Cat]

Has nothing to do with affording, I prefer analog. If I couldn’t afford a dash, I’d just sell one of my 13 vehicles.

They ARE analog ! I was being sarcastic since you said the odometer was 'digital"

 

[cheveslakr]

Had the same issues with my '73 pickup. I actually have a schematic showing the routings very well. I tested continuity on all the pathways, then applied a touch of dielectric grease on the terminals after a good cleaning. Got everything to work but the ammeter. I think I'm going to just change that out to a voltmeter and wire it directly.
Mine has the gauges, and the repop printed circuit is $70, if I have any more issues, I'll go that route.
Yes, mine was brittle also.

 

[mike1369]

Having a similar issue on my 70. Everything in the cluster is new except the speedo and tach. Solved my lighting issue by adding an additional ground to the rear of metal cluster ‘fish’ to the body. However my turn signals on the cluster aren’t lighting up when the front/rear turn signals are flashing. Gonna try unplugging the cluster and plugging back in to see if I have the same issue. Thank You.

I feel your pain, Let me know if unplugging and replugging works. If not take a look at the instrument schematic I attached to my post. You will see were the power comes in for the Turn Signal Lamps (TSL). Check and see if your TSL flash when you put the emergency flashers on. The TSL circuit can get confusing, do have a complete electrical drawing for your car if not I think I can post one. Follow the circuit for the TSL from the switch. keep in touch. Cheers hope this helps. Mike