Powerboost Ticking When Stopped, Disappears When Moving

[Jerome10]

Got a new noise today. I am familiar with the aux pump kinda high-pitched electrical whine noise. This is something new and different.

When coming to a complete stop, as soon as the truck stops moving, something has started clicking or ticking. Truck is in electric mode, so engine completely off.

Sitting at a stop it makes this clicking the entire time. The instant I release the brake the clicking stops.

Confirmed it now twice today.

Any ideas here? I’m guessing it is the transmission since the engine is off. My other thought is could it be something with the brake system?

Will monitor but this one is weird. Will also try shifting to neutral or park and see if it stops.

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[Tosh]

If you have your cab ventilation (A/C) fan on, I would shut that down and see if the noise persists.

I don't know what else might be turning when the ICE is off. and the vehicle is stopped. AFAIK the traction battery cooling system depends on the ICE cooling pump, unlike a BEV which has one or more electric fans running all the time

 

[Lefty665]

PBs and EBs have an electric vacuum pump for the brakes. Sound seems consistent with that.

 

[Jerome10]

Appreciate the info. Has been 5-ish days now and I've never heard it again. I generally keep an eye on coolant and break fluids every month or two. Will check brake again to be sure.

 

[Lefty665]

That's a vacuum pump, not a liquid pump. Checking brake fluid level will tell you nothing about it.

The EB and PB are supercharged so do not create intake vacuum like a naturally aspirated engine. They do not produce intake vacuum used for the power assist to the brakes. That is why there is a separate electric vacuum pump on vehicles with those engines.

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