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Topic: Engine battery question (Read 424 times) previous topic - next topic

Engine battery question

I'm firmly convinced that my fluctuating voltage issue is due to something not making a good connection. On the travels this week I hit a very rough stretch of road, and the needle on the dash looked like a windshield wiper, while the computer display was going from green to yellow to red and back again just as rapidly. This winter I'd like to physically trace the wires for that. Since the computer reads that from the diagnostic port, there has to be some place where the coach's computer gets the information from.

My thought is that one of these days I'm going to run a temporary wire from the engine battery terminal on the isolator to a digital volt meter up front, where I can monitor it while actually driving. If, as is suspect, that voltage remains fairly constant, that will tell me that I need to find out where the bad connection might be.

Where is the coach's computer located, and how does it get the engine battery voltage?

Re: Engine battery question

Reply #1 –
David,

There are only two "computers" in your coach. The engine ECU that sits on top of the engine just behind the turbo and the transmission computer located on the front firewall. The Audit display only reads voltage, tank levels, etc and is not a computer.

You can see where the connections for the ECU and sensors in the Foretravel library and can start your search above in "Media" for the U280/U300 12V schematic.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Engine battery question

Reply #2 –
Thanks, Pierce. The old Audit system is long gone. I'm guessing that the engine computer is the one I want.

Re: Engine battery question

Reply #3 –
Yesterday I pushed on every wire and connection if could on that computer behind the turbo. Today the computer showed mostly 13.4, with a few minutes of less, but 12.8 or above. A few times I thought I saw the yellow light, but by the time I looked it was back to green. I did actually see 12.7 (yellow) once.

Of course, yesterday I bought a 100' roll of wire and two "cigarette" outlets. Couldn't find any plug-in volt meters in the two stores I checked. Next week I'll look a bit more, and order some if necessary. We're not planning to go anywhere anytime soon, so I've got plenty of time to poke and prod.