TriPac APU Alarm Codes

Ok so I replaced alt today the old alt was putting out 14.5 14.6 while apu was running but it still through the alt code after. When I said the alt was putting out 12.8 13.0 volts I ment to specify where I got that reading from I didnt mean to say inverter I got it off the back of alternator itself with a volt meter. Now with new alternator I still get alt code the next move I'm going to make is to replace the belt I'm kinda at a loss right the last place I want to go to is thermo king

 

Your getting the alt code because the control box isn’t seeing the voltage from alternator

 

There is a wiring harness/connector close to the alternator that either corrodes or breaks. This would explain your good voltage at the alternator itself, but none at the inverter and a code on the control.

 

Ok so how do I check the control box an see why it's not getting the proper voltage? Also the new alternator gets 14.5 from wires on back of alt an gets around 14.5 14.6 at inverter. I only have a tv plug in nothing to crazy il take another look at the wires again because it did sit at Detroit dealer getting a complete inframe for about 6 months because it has that good ol dd15 an parts was on back order so I'm sure the mechanics didnt crank the apu while the engine was tore down so maybe a wire could have corroded but I tried to do a thorough check while changing alt didnt see nothing to far out the norm. Any more suggestions would be greatly appreciated

 

SortS, if the coolant was completely drained.

 

Just came across this thread a little while ago. I purchased a used truck with Apu and found out it is an 05 model tripac. When I first got the truck the Apu would crank and then quit like it had to little or no freon. After checking a few things I go to thermo king and found out the condenser on back of can was firty. They cleaned it and it worked great.

The other night it started running rough and then it cleared up. After a couple of nights it shut down and I kept getting the ENg code found a broken wire at the water pressure switch (under the thermostat) fixed it and then putting it back together the little table on the switch broke I just replaced it an hit the reset switch and it works.
Now the thing is running rough again and I looked and found that the last service was done about 1 thousand hours ago. Could it be that it just needs a service? I am going home next week and will service it then.
Thanks for any and all information.

 

Sounds like a fuel related problem,filter,sucking air etc. you should have two filters a normal one and a small one bolted to the back of the box.

 

I have a clear inline filter and a regular fuel filter. That is how I found out the Apu is an older one the parts guy at thermo king said it had to be an older one and he asked for model and serial number.

I figured it was something to that effect. I am going to change oil and all filters next week when I get home.

Thank you for the information.

 

Another thing is that it is low on oil (not down to add mark). Could that be an issue?

I hate to ask stupid question but have never dealt with an Apu .

 

The one I have will burn oil down to about halfway on the dipstick, and it doesn’t run rough.