Localliquid Posted March 14, 2016 Share Posted March 14, 2016 1989 mcr Mack with 300 hp. Engine brake is intermittent. It used to cut out at around 1900 revs but now seems to about 1500 revs. After that it cuts in and out. If some one could tell me where is the sensor located that would be appreciated. Cheers from South Australia . Quote Link to comment https://www.bigmacktrucks.com/topic/44327-engine-brake-switch/ Share on other sites More sharing options...
fjh Posted March 14, 2016 Share Posted March 14, 2016 You will likly have to change the switch in the fuel pump Bolts to the rear of the pump at the top! 2 Quote Link to comment https://www.bigmacktrucks.com/topic/44327-engine-brake-switch/#findComment-327443 Share on other sites More sharing options...
mrgumby Posted March 14, 2016 Share Posted March 14, 2016 there is also a relay for the engine brake have you tried a new one..check the pump switch and the clutch pedal switch 2 Quote Link to comment https://www.bigmacktrucks.com/topic/44327-engine-brake-switch/#findComment-327444 Share on other sites More sharing options...
gearhead204 Posted March 15, 2016 Share Posted March 15, 2016 or you could bypass the fuel pump and clutch switch and install a "Jacobs" floor mount foot switch, I personally like this set up as it will only work when you step on it, I have mounted them to right of the throttle....... I don't know if Aussie pedals are backwards if so, mount to the left of the GO pedal. Quote Link to comment https://www.bigmacktrucks.com/topic/44327-engine-brake-switch/#findComment-327508 Share on other sites More sharing options...
Tbear Posted March 15, 2016 Share Posted March 15, 2016 I just changed the clutch switch to fix my 98 ch 613. Mine was intermintet just not at a certain rpm. good luck Quote Link to comment https://www.bigmacktrucks.com/topic/44327-engine-brake-switch/#findComment-327517 Share on other sites More sharing options...
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