MackMack613 Posted January 24, 2016 Share Posted January 24, 2016 93 CH613, my brake lights stay on all the time. The fuse that controls the tractor lights also powers the trailer stop light relay. I have taken my turn signal switch apart and cleaned it and nothing had changed. When I put a test light to the primary and secondary air switches, one switch lights up fine, the other not so much. When I probe the pole on it nothing, then if I just roll the light a mm it lights up. Note: there was no trailer wiring installed before the symptom started. Looking for a direction on where to goThanks Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/ Share on other sites More sharing options...
Mcrafty1 Posted January 24, 2016 Share Posted January 24, 2016 On my 86 R model there is a pressure switch out under the cowl on the firewall, the switch is plumbed into an air line with (if I remember correctly) one wire connected to it, every spring when I get ready to use the truck this switch is stuck....I tap it a few times and it releases and works fine the rest of the summer, maybe this is where you could look for your problem. The switch could be stuck or failed..Hope this helps. I believe the switch requires air pressure to switch it off...I say this because I usually have to have the brake pedal compressed for my described 'fix' to work. Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321323 Share on other sites More sharing options...
MackMack613 Posted January 24, 2016 Author Share Posted January 24, 2016 Thanks for the direction my friend. I will start there Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321360 Share on other sites More sharing options...
Vladislav Posted January 24, 2016 Share Posted January 24, 2016 I once had such an issue and found out (with a help of this forum folks) that my trolley valve lever was moved a bit. I was surprized that lever could do anything to the truck with no trailer but it lightened up my brake lights instantly. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321395 Share on other sites More sharing options...
MackMack613 Posted January 24, 2016 Author Share Posted January 24, 2016 10-4 Vlad I'll check the things comin off the trolley valve Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321402 Share on other sites More sharing options...
turckster Posted January 25, 2016 Share Posted January 25, 2016 The brake light switch is located right next to the clutch lever on the firewall inside the cab. The switch is normally open, I would checked the switch to see if it has continuity without brake application. Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321460 Share on other sites More sharing options...
Popular Post MackMack613 Posted January 26, 2016 Author Popular Post Share Posted January 26, 2016 Update: it was a leak in the trolley valve keepin the lights on. Thanks guys for all the help 3 Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-321682 Share on other sites More sharing options...
Joseph deluca Posted August 26, 2019 Share Posted August 26, 2019 I have a99 Mack and the brake lights stay on all the time . I replaced the switch and relay but still the lights are on Quote Link to comment https://www.bigmacktrucks.com/topic/43677-brake-lights-on-all-the-time/#findComment-430838 Share on other sites More sharing options...
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