Jomorisn Posted March 2, 2021 Share Posted March 2, 2021 My speedometer works fine until I turn on my head lights then it reads high if i shut the truck off and lights and start up it works fine. Thanks in advance john Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/ Share on other sites More sharing options...
Joey Mack Posted March 2, 2021 Share Posted March 2, 2021 take the cluster out and clean the ground post on the cab frame. It's to the left, take the star washer out and toss it. trim any heatshrink glue that may have oozed out and re=install it. also do the same at the fues panel on the right side and also check the ground breaker on the firewall next to the starter relay, clean the frame ground behind the left steer tire and the big 5/8" ground bolt on the engine block in front of the starter... joey... Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/#findComment-469815 Share on other sites More sharing options...
Jomorisn Posted March 13, 2021 Author Share Posted March 13, 2021 I have cleaned most of the grounds and will cleanup the rest. Thanks for taking the time to answer my post. I really appreciate it I will let you know how I make out. Thanks again John Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/#findComment-470556 Share on other sites More sharing options...
Joey Mack Posted March 13, 2021 Share Posted March 13, 2021 👍 Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/#findComment-470559 Share on other sites More sharing options...
Jamkar Posted January 24, 2022 Share Posted January 24, 2022 How’d ya go John? Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/#findComment-487822 Share on other sites More sharing options...
Jomorisn Posted December 22, 2022 Author Share Posted December 22, 2022 I cleaned all grounds and still have the issues. Maybe bad speedo? Quote Link to comment https://www.bigmacktrucks.com/topic/66084-2002-mack-ch-427-speedometer-troubles/#findComment-518847 Share on other sites More sharing options...
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