nickjames138 15 Report post Posted March 26, 2016 So, I lost my tach after switching to an MSD ignition. (That's the first problem). I just went to switch all of my gauge lighting to LED none of the bulbs are working except for the turn signals. I got one gauge light working for a second and then it flickered out. The high beams light worked pretty well, but I changed the circuit board and I can't get it to work again. My clock light on the passenger side alsodoesnt work. My fuel and speedometer gauges and clock still work. Do I need to change the headlight switch? I keep hearing rheostat, but I don't know what or where that is? Quote Share this post Link to post Share on other sites
Hoover 12 Report post Posted March 26, 2016 The headlight switch has a rheostat in it. That is what adjusts the brightness of your gauge lights. Quote Share this post Link to post Share on other sites
ray1970 88 Report post Posted March 26, 2016 May not be much help When I went to the MSD there was a tach compensater thing i had to install to get the tach to work. When I changed to LED dash bulbs almost nothing worked????? Turns out the bulbs i used have a positive and a negative side.... flipped the ones that didn't work 180 .....All was good.. Quote Share this post Link to post Share on other sites
Kris 90 Report post Posted March 27, 2016 I'm not sure if this is your part of your problem but my friends and I have had a similar issue with led's. Most led lights aren't bidirectional meaning there is a definite positive and neg side. You have to have them plugged in so the correct wire on the light matches up with the correct contact of the circuit board. . I had an issue like this with a few of mine and just turned the light the other way and they started working. I figured it out be testing my lights with a 9v battery. You could touch the light to the battery and it wouldn't light up, I flipped it around the other way and tested it again and it worked. Try unplugging the twist in light holders for the ones that don't work one at a time and turn them so the tabs on it touches the opposite contact it was previously touching on the circuit board. This should work unless you have another issue. Quote Share this post Link to post Share on other sites
ray1970 88 Report post Posted March 28, 2016 The MSD tack fix? PN 8910 It fixed my tack so it looked like is was working... The fact my tack hasn't showed over 4500 rpms in years didn't change.. But it worked good till than.. Quote Share this post Link to post Share on other sites
