I have a 2006 Volvo Vnl670 with an Isx 500hp and Meritor 10spd trans. I started losing power from time to time. Lately it only happens once a day during the first 30 min of drive time. I will lose throttle completely and my speedo will die to 0. I already replaced the Speed sensor and replaced both harnesses that go to the transmission. Also i left the truck with a mechanic for a week while he was divging through wires, found a few rubbed wites that he fixed ...... still, the problem did not go away. Someone told me they had a similar problem on a Kenworth and it was the turbo control valve, mine was leaking anyway so i replaced it. I already have spent so much money and lost weeks of work and did not find a solution. PLEASE HELP!!! Problem usually happens when going uphill or hit a bump. Also the problem goes away on its own in about a min or two or if i turn the truck off and back on while its still rolling. Maybe a good thing to mention, i did have a speedo problem before where my exciter wheel by the transmission yoke was lose so my mechanic tightened the yoke and the speedo problem went away but i never lost theottle like this.
Losing throttle completely
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Fidus, Oct 27, 2017.
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Pedigreed Bulldog Thanks this.
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But since you said it happens when you hit a bump, maybe focus on the wiring first and it's free. Check the harness where it goes over the valve cover and around clamps, just anywhere it could rub. -
What Cummins faults are logging when it loses throttle? I agree on APP sensor and is usually mounted on the throttle pedal. Checking the wiring from the pedal to the engine. Always start with good clean and healthy batteries and connections also.
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Batteries are brand new and i cleaned them again and put electrical grease on all connections.
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By what I can see, you have a datalink issue somewhere between the engine ECM and either the transmission and or the ABS whichever is reporting road speed to the Engine ECM. Sorry don't have more, not a Volvo guy.
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Might check your throttle peddle, too. Fly-by-wire usually has a motorized pot in the peddle assembly itself that sends a variable voltage to indicate the throttle position to the ECM. Pretty sure the TPS would be incorporated into that, since it wouldn't make sense to have another sensor elsewhere providing the ECM with the same data it's already getting from the pedal...unless government was involved in the design and execution in which case wasteful ridiculousness is SOP.
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If it's happening when you hit a bump than it's a loose ground or shorted wire somewhere.
Double check all battery and starter connections for loose or chafed wires.DudleyBoyNC Thanks this.
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