Rick whitmore Posted March 10, 2016 Share Posted March 10, 2016 Hello everyone, I have never posted to this forum before. I have a 99 Mack RD688S with the headlights stuck on. I unplugged them from the switch in the dash and nothing changed. I unplugged them at the wiring harness out in front of the engine. Do I have a short or could there be some fuse or relay problem. thank you for any help anyone might be able to offer Quote Link to comment https://www.bigmacktrucks.com/topic/44288-headlights-stuck-on/ Share on other sites More sharing options...
AZB755V8 Posted March 10, 2016 Share Posted March 10, 2016 The only way the lights are on is if there is power to them, you have got a short. Don't think it's is a ground problem. No relay in that circuit in most all Mack's. Start tracing the 2 wires back to the dash, third wire should be the ground. Quote Link to comment https://www.bigmacktrucks.com/topic/44288-headlights-stuck-on/#findComment-327087 Share on other sites More sharing options...
Rick whitmore Posted March 17, 2016 Author Share Posted March 17, 2016 thank you for the help...after several wasted hours of looking for a short--we figured out the driver had not pulled the parking brake on. Therefore, daytime running lights were on. At least nobody got run over. Quote Link to comment https://www.bigmacktrucks.com/topic/44288-headlights-stuck-on/#findComment-327703 Share on other sites More sharing options...
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