Totenhofer

Hey guys, ok so I’m aware there’s plenty of Jake brake threads on here but none that quite cover my issue, 1999 Mack fleetliner chr 470, in the morning when I start the Jake brake will work on both high and low selections, but say 10 minutes into driving the Jake will Only engage in The first stage but only when the switch is all the way down, and the second stage will not work whatsoever, and having the switch in the middle position it will do nothing either. It’s very dangerous and frustrating as I really need to use the Jake for the work I do and at this point the first stage of the Jake is no better then putting your hat out the window to slow down. they both work fine at the start of the day, it happens every day without fail. It’s stumped me. thanks guys Sam

Cheers, Yeah park brake light is always on the dash, and yeah brake lights will come on with low air sometimes , is it a sensor that controls this or the actual park brake switch itself? thanks. Sam

Cheers mate. noy sure why it was still flashing 4.1, now it’s changed I reset the isolation switch on the truck, it’s flashing 7.2, 7 times then 2 times. do we know what the combination means? thanks guys

Hey mate thank you so much for the advice, ok so replaced speed sensor, completely different truck to drive, base of the sensor was all broken away looks to have been screwed in to far. is now running at around 29/32 psi boost so was definitely derated. So I tried what you said with the cruise control, the electronic fault light flashes 4 times then goes out for a second then flashes once then goes solid again. So the sequence is 4.1If that makes sense, and it does that every time I hold down the set/deceleration button. Thank you again Sam.

Hey guys, just purchased a 1999 Mack ch fleetliner with a 470 and Mack 18 speed cant seem to find any information on this topic, the speedo has just randomly decided to stop working and now it feels underpowered only light on the dash is electronic fault. And what boost do the early 470s make it’s just always felt underpowered from the start.