led dash indicator flashing

Dash LEDs flicker on quickly when other system switches are shut off. Keep reading to get the whole story and if you may have some info to try and solve. I am working on finishing up a project of wiring up a complete car. It is a 1986 Porsche 911 converted for a hunting / winter driver. The car is a former race car complete with roll cage and a custom, one-piece carbon fiber dash panel. Most of the dash has stayed as-is from the racing days and I just modified the wiring to add things like turn signal indicators, high beam indicators and defog indicators. All these indicators are cheap LED's that the customer purchased. As I finally get everything working, I notice that the indicator LEDs are just giving a quick flash when turning off unrelated switches (such as fog lights, blower fans, ect...) or hitting the horn. I have been unable to narrow down why this is happening. There are secondary LEDs on the front bumper that are also flickering at the same time. All the LEDs just flicker once - all at the same time - and then shut off. All the grounds are good and solid. The LEDs are 12V and made for automotive use. The grounds are common with the gauges and incandescent lights in the dash and the ones on the front bumper use the same ground stud as the battery. I have tried putting a diode into the ground and that did nothing. I put a resistor inline on the power side and still no luck. I read voltage across a resistor to only show 3mA and read voltage from power side to ground and only got 4mA. Voltage on the ground side showed 2mA. I am open to ideas to try or things to check. I can provide any info anyone may need to help with this issue. Thank you!

The car is a custom 1986 Porsche 911 SC.