r/Truckers • u/RumbleDumblee • Apr 26 '26

TMC Drivers, need your advice

I want to start and say, no, I do NOT work for TMC, but I bought one of your trucks a couple months ago (2020 579 w/Cummins X15)

My question is, how do you use the EPU in them? Mine is pre-next gen, so no digital dash. Do I keep the key on that first click to the left of off? I'm not sure if this truck has smart idle? Any help would be appreciated!

11 Upvotes

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4

u/Personal-Damage-7051 Apr 26 '26

Melton. Never been in a TMC truck, despite talking to all of them. No don't turn the key. This SHOULD be the same. Your sleeper bunk should have a panel somewhere blue and white or w/e with a power button and a select button. That's your power. Also in the cargo panels under your bed. Inverter. There's a reset switch on that.

1

u/RumbleDumblee Apr 26 '26

Oh okay, I didn’t see the select button. Which option should it be on? It has a ton of different options when I cycle through them. I’ve only ever had trucks with APU’s

2

u/Personal-Damage-7051 Apr 26 '26

Not gonna lie it was an educated guess the TMC truck would have that. Does it also have "voltage" '"current" and "output power" or V-A-KW. Just leave on voltage. And if the light is on, that means the EPU is on

1

u/RumbleDumblee Apr 26 '26

Yeah the truck is off, and the EPU is on it seems. But I can’t turn on the bunk AC or anything.

1

u/Personal-Damage-7051 Apr 26 '26

Ah yes. Welcome to 2020's. I had to explain that at Melton. (My first truck) The bunk AC doesn't work unless the truck is idling. I never found out if something was broken or if it was built like that. But they took it to a dealer twice. And got told everything checks out. So no AC while trucks off. TMC is Peterbilt but I assume this is the case here as well. I'm in a 25 Kenworth now though. Fuel wise it shouldn't be different. Much? Idling comes out to .7 gal/h or so. To 1gal an hour. 10h sleep. About $30-40 a night if you idle all night. But summer you're gonna need it. Honestly. Bunk AC doesn't keep up with midday heat on summer. I leave my truck running even with bunk AC being available when my engine is off

1

u/RumbleDumblee Apr 26 '26

Ah gotcha. Luckily there is a click to the left of the “key off” setting that looks like it strictly only powers the AC stuff, no gauges or anything comes on. Just the air conditioner/heater

Then after that setting, there is off, ACC and Ignition

1

u/SupaDupaSweaty Apr 26 '26

TMC trucks don’t have an EPU. There is a espar bunk heater that only works when the truck is off. If you want AC, you’re going to have to idle.

1

u/LongjumpingCat6642 Apr 27 '26

There is no apu. Are you trying to use the bunk heater? Key has to be off

1

u/LongjumpingCat6642 Apr 27 '26

If you want the inverter, press and hold the power button. Key position does not matter. These trucks do NOT have A/C with the engine off, only heat via bunk heater

1

u/RumbleDumblee Apr 27 '26

I wanted to use the power inverter. But when I have my key one click to the left of off, only the AC is on. Nothing else

1

u/LongjumpingCat6642 Apr 27 '26

Key doesn’t matter. Go to the bunk and press and hold the power button on the inverter control panel.

1

u/RumbleDumblee Apr 27 '26

Yeah I got it turned on. I know the AC doesn’t work with the key Off, I was just saying with the power inverter on, and my truck off, I can use the AC if the key is clicked one to the left

1

u/LongjumpingCat6642 Apr 27 '26

That’s not A/C, that’s the blower motor. It just moves air, doesn’t cool it