Jeremy_Brault 3 Posted June 9 Can anyone tell me what the purpose of the ground relay is on the firewall of a Mack truck? Do I need it or can I bypass Share this post Link to post Share on other sites
Macktech689 53 Posted June 9 That is a circuit breaker that protects against system damage it there is a battery short to ground. Personally I would not bypass it. 1 Share this post Link to post Share on other sites
