Topless69GT 28 Report post Posted April 20, 2015 I am having two different issues with the wiring in my car. The first one is with the instrument cluster (tach dash). The dash lights on the left hand side of the cluster will not work including the left turn signal indicator but the turn signals are functioning on the outside of the car. I suspect it is a problem with the flexible circuit board or whatever it is called. It is a reproduction one. The second issue it that when I push the brake pedal my dash lights are coming on (all except the left side of the cluster -see problem above). Brake lights do work but the dash lights are coming on as well whenever the pedal is pushed. I am not sure if it is a brake light switch issue? Has anyone had these issues and knows how to fix them? Quote Share this post Link to post Share on other sites
SparkyGT 26 Report post Posted April 20, 2015 sounds like a bad ground in the printed circuit, you may be able to run a seperate ground wire to get the others working. Quote Share this post Link to post Share on other sites
Rsmach1 71 Report post Posted April 20, 2015 Did you just get the printed circuit board? If so exchange it, I've seen a few threads where there are bad ones out there. Quote Share this post Link to post Share on other sites
det0326 179 Report post Posted April 20, 2015 IMO if the instrument lights are triggered when brakes are applied there is a wire wrong somewhere. The circuit film could be the reason for some of the lights not working though. Is it factory tach under dash harness? Dave Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted April 20, 2015 It is a harness that was converted to tach/AC harness. Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted April 20, 2015 The printed circuit board is over a year old but has only recently been installed in the car. Too late to return or exchange it. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted April 21, 2015 Definitely sounds like a grounding problem with one side of the circuit board, but I can't come up with an elegant explanation for the brake issue. Was this a harness I converted? If so, please consider sending it back to me on my nickel if you suspect the wiring. Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted April 21, 2015 I ended up with two converted harnesses. One from Pat White and the other from you. I am not sure which one I used. The other one is still in the box so it would be easy to figure out. Worst case scenario I can put the other one in and see if it fixes the problem. What is the best way to ground the circuit board? Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted April 21, 2015 The circuit board is grounded via the underdash harness: a ring connector typically near the headlight switch goes to the chassis via a screw. For a tach dash, the circuit card has two separate sections for lamps and grounds for each side. My suspicion is that the circuit card has a break in one of those traces or is not making contact at the connector. Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted April 29, 2015 Bought a new flexible circuit card and it fixed the dash issue with the exception of the dash light coming on when I press the brake. Only does that when the headlights are off. If the headlights are on then there is no change when the brake is pressed. That is the only electrical issue I am having and I think I can live with it. I am afraid if I change out the wiring harness I am asking for trouble. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted April 30, 2015 That's so weird. The brake light signals are completely separate from dash lamps with the exception of both start at the headlight switch. Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted April 30, 2015 Maybe the headlight switch is the issue? I will replace it while my dash is apart and let you know. I hope it is that. Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted May 1, 2015 It was the headlight switch. I bought a new one and it solved the problem with the dash lights coming on when I hit the brake pedal. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted May 2, 2015 Woohoo! I got it right! Glad your problem is resolved! Quote Share this post Link to post Share on other sites
