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Bigjohn4300

Lost cruise and engine brake

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I recently purchased a 2004 Granite cab and chassis with 80xxx miles on it. When driving the truck home from Indiana to Louisiana, both the engine brake and cruise control stopped working. All the fuses look ok, and we have tried swapping breakers, to no avail. Has anyone had this issue before?

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Don't forget the air pressure switch on the brake manifold, when you release the park brake you activate an air switch that turns those both on.

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Cruise switch should work as an electronic hand throttle with the parking brakes set....just saying...but they will not set with the clutch "In" (switch open) or foot on the brakes (brake lights on)

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if it was the break switch jake should still work but not the cruse id be looking at the clutch pedal switch first try lifting up on the pedal with the top of you're foot if then check the switch adjustment and if all that fails check the switch itself with a multimeater.

Good call....didnt think that through, *thumbs up*

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Any "lightning bolt" codes? (Electronic malfunction) to check have the cruise control switch in the off position, then press "set" on the other button. If the light is on, it will blink a code line --- - which is 3-1. Tell us what you get.

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Sorry been away, no clutch switch(allison) and can't seem to pull code because the switches appear to have no power to them, they don't light up when you turn them on

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Sorry been away, no clutch switch(allison) and can't seem to pull code because the switches appear to have no power to them, they don't light up when you turn them on

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If you can't read the codes, I guess I would go to mack and get them to pull the code. Probably will point out the issue right away. You did try and read them with the cruise control on/off botton in the OFF possition right?

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I'm not positive on that, I'll try it again tomorrow morning, thanks

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Yes, tried with cruise switch off, appears to have no power to the switches, will start tracing wires to the switches when I get a second, found a breaker that is unlabeled, but is hot as a firecracker, that may be the feed to those two controls and has shorted out, maybe

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True, breaker could be faulty. Try searching which breaker controls the two, (likely same one) and try replacing. It seems to me though that the code should have done something using the breaker power from the lightning bolt computer..

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Ok getting somewhere, found a circuit tied into the cruise circuit, I think a remote throttle setup for the trucks previous duty, removed it and now we have power to both systems, cruise works correctly, but still no engine brake, switch is lit when it is on, but no brake, I can also now pull up a code 3-5 via cruise/lightening bolt, any ideas?

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This was a cement truck previously, the additional circuit tied into cruise ran to back of frame drivers side, I think it was to control idle speed on site, wires were cut to remove mixer

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3-5 is for "Engine Brake Output #1" could be high voltage or open OR low voltage.

A 3-6 is same, except for #2. I'm guessing 1 and 2 is for solenoids under the valve covers?

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Ok so the code is for the brake, good I guess, I'll start looking this weekend, any idea what the "engine brake disable" relay in the fuse panel is for?

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Probably for when a driver pushes on the clutch or is on the gas pedal. Thats why most clutches make that tiny click noise when you start to press it, just telling the computer to stop engine braking.

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