APU Problems

Topic 28750 | Page 1

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Pete W.'s Comment
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Hello all, I have an evolution tripac 2016 that is acting up. My problem is: woke up to a red triangle nothing else just red. I reset the HMI and watched, listened. No cabin fan, no engine crank or start and all HMI lights work, set to AC and after about a minute I get an amber warning (triangle). Still no cabin fan, no apu crank, all HMI lights work & that blasted amber triangle.

What I've done: 1. I've checked all the fuses under the steering column. 2. I checked the 50 amp fuse in/on the unit (APU) 3. Did a suggested reset of "turning off apu power at the engine switch" for 20 minutes then another 40 minutes 4. Tried a suggested reset by "removing the 7.5 amp fuse in the main box while the HMI was powered off then replaced the fuse and powered on the HMI. Still no fan, no engine crank and the amber triangle. 5. All fluid levels are good with no leakage. 6. recently I've replaced my water pump belt (7 days ago). I noted that it severed the bleed line from the thermostat housing when it broke. since it was only a bleed and thermoking did not have the part in stock, I zip tied it to my coolant (rubber) hose until I can get the part. 7. I pulled the USB cable out to try and read the programming but it too is not working.

side note: this is on a 2016 KW T680 Engine has 145000 hours and is serviced regularly, and air filters are checked, changed out and clear.

Any insight or help would be greatly appreciated. Thanks in advance.



Hours Of Service

HOS refers to the logbook hours of service regulations.


Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

PJ's Comment
member avatar

Mine is older but still a thermoking. First check the circuit breaker on the side of your black box under the bunk. Sometimes they trip when it experiences a no start condition. If that isn’t it check the charge wite from the alternator. They sometimes get corroded and break off. I would also check your master switch on the unit. Once mine vibrated loose just a little and it would not start.


When a violation by either a driver or company is confirmed, an out-of-service order removes either the driver or the vehicle from the roadway until the violation is corrected.

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