Thermo king apu "Error 9"

TK Tri Pac owners manual: https://www.sfitrucks.com/Prod/ImageDocs/TriPacOwM.pdf

Fault codes in the book aren't showing anything for "9". Is the system alarm/fault light on? Is it possible that the display is messed up and the "9" you see is actually the "g" on the code for "Eng"?

 

Try this: Turn off power at APU control in the sleeper, kill the engine switch on APU itself. Now look under the bunk ad you should find a reset switch on the APU's electronic control box. That will often reset the issues.

FYI: you can force an APU regen (at least on freightliner). While rolling at 50 mph +, press the APU switch on the dash "up" and hold for about 30-60 seconds. The light will come on indicating a regen is needed. Now press up again and hold till it flashes (regen in progress). Maintain 1200+ rpm as best you can till cycle is finished.

Also, Google the thermoking Tripac manual. It is available for free online and you can save it to your computer.

 

That's probably it.......the screen uses numbers to spell with.......when mine is on standby the screen reads 56y. If you look at it long enough you can see where the 5 kinda looks like an S, the 6 kinda looks like a lower case b and then the y (Sby)

Engine code is usually related to an oil pressure or coolant issue. Is the red light on in the top right corner. Also, what year is yours.

 

mine did the same thing a couple weeks ago with the system fault redlight came on and it said eng on the panel. just had to find the reset switch and good to go ever since

 

The En9 code only comes on if the run circuit is energized and either high coolant temp or low oil pressure. Of course the oil pressure will be low any time the engine isn't running, so that alone doesn't tell you much, but if you make sure the switch in the APU box is on, and reset the reset switch under the bunk, then turn the sleeper controller off then back on, it will de-energize the run circuit and clear the En9 code.

Of course there may be good reason for the code, such as low oil level or broken water pump belt, etc, but once the code is cleared, the engine should start when the run circuit is energized again, then only trip again if the problem still exists.

 

where are you at? and what's the ambient temps been?

On these 90+ temp days, I have had a couple times when my APU will trip the ENG code. I let the APU cool off and then I've had to open the service panel on the APU and leave it open to let the heat out it seems.

Make sure you didn't close any of the coolant lines to the engine block too.

Last time it happened on Thursday, I was able to finally determine that yes, the cooling fan on the APU was actually kicking in and working. The radiator though inside the APU could use a good cleaning. I am(was) hoping that I could have washed it this weekend, but we've been having rain showers all weekend. Hope I can get at it today sometime before I leave on Monday.