DieselDog5.9 Posted October 31, 2022 Share Posted October 31, 2022 Have a 99 Mack RD686S that the stop lamp circuit has a mind of its own, looking for the stop lamp switch, but have found 4 switches in the air circuit, but not sure what is what. Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/ Share on other sites More sharing options...
Solution Popular Post Joey Mack Posted November 1, 2022 Solution Popular Post Share Posted November 1, 2022 The brake light pressure switch on an RD, is on the fire wall under the hood.. in the center.. Beware, it is hot all the time regardless of ignition position.. Jojo 3 Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/#findComment-514200 Share on other sites More sharing options...
DieselDog5.9 Posted November 3, 2022 Author Share Posted November 3, 2022 I Did find it, had fallen down on the intake manifold and shorted out. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/#findComment-514325 Share on other sites More sharing options...
Joey Mack Posted November 3, 2022 Share Posted November 3, 2022 were you able to fix the issue? and have brake lights working again? jojo Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/#findComment-514327 Share on other sites More sharing options...
Mackpro Posted November 4, 2022 Share Posted November 4, 2022 On 11/1/2022 at 11:38 AM, Joey Mack said: The brake light pressure switch on an RD, is on the fire wall under the hood.. in the center.. Beware, it is hot all the time regardless of ignition position.. Jojo I always found it weird that they hid the brake light switch on the outside on the RD’s with an ETECH engine. I can’t remember If the earlier RD’s were like that as well. Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/#findComment-514355 Share on other sites More sharing options...
DieselDog5.9 Posted November 5, 2022 Author Share Posted November 5, 2022 Yes, the owner has had fantom light issues for multiple years, all set now. What an odd spot to hang a stop light switch. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70640-99-mack-rd686s-stop-light-circuit-diagram/#findComment-514376 Share on other sites More sharing options...
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