'02 300M

Had the flickering dash lights / headlights problem the ended with the headlights looking like strobe lights and an eventual blow out of the head lamp bulbs on the interstate. the fix, replace the negative battery cable. Grounding issue.

Now I notice several months later that at night my instrument cluster gauges are dim as if I have them turned down with the adjustment wheel on the light switch. I can turn the wheel back up past the click to full bright and the odometer and shift display go full bright, but the speedo and tack stay dimmed.

Any suggestions on what the problem is and how to fix?