2006 Cat 277B track loader

Hello, I am a new member here hoping to get some help on a 2006 Cat 277B that has had starting issues for a few months.
SN: CAT0277BCMDH03847 2200hrs.

The battery went dead over this past winter after sitting so I replaced it and got nothing when I turned the key switch. So, I took the positive cable off and it was pretty corroded, so I replace it as well, machine fired right up. Well, after using it a few times, when I would turn the key switch it would hesitate to fire up and it got progressively worse till the point that when you turn the key power goes out and I have to reset the key switch to get power back, but continued to do the same thing.

Things I've done to it:
I had the started rebuilt, put a new battery in it, new pos battery cable, it has 12.2 volts during all my testing, cleaned the 105A circuit breaker connections, cleaned the starter connections, including the 304 wire, cleaned the ground on the started from the Neg battery terminal, cleaned the wires on the power stud, checked all CB's and swapped relays in the CB # 2 block just to see if one might be going bad. I bought a 30amp 5 pin relay and swamped each one individually in the 4 relays on the right side in the eng compartment and nothing, swapped the start and cold start relay with the new one I bought and nothing. Also, I bought a key switch and swapped it in with the same result. I know, parts replacing at it's best.

When you turn the key on the lights are no longer lighting up, they were coming on solid until you turned the key, then they started intermittingly coming on and flickering out and now nothing. Almost like a capacitor drained out. But I don't believe there is one on it that does that. Just trying to state what the machine is doing as best I could.

It seemed like a poor connection at first but now I am at a loss with everything I have done to it. I don't have the shop manuals and hate to get a dealer involved as I do most all of my servicing and work on my equipment but have never worked on one of these machines. I am not sure how to get to the ECM to check connections but it seems like that might be where I need to go.

Any help would be greatly appreciated and hopefully I am posting in the correct place. Thank you.

Is there anyone out there that might be able to help?

Jeremy Sailee said:

I am not sure how to get to the ECM to check connections but it seems like that might be where I need to go.

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The ECMs are under the floor. You'll probably find them buried in dirt/mud. It seems to be typical for any machine like this where the cab has not been kept clean.
See the attachment which is the complete breakdown of the chassis wiring.
I don't know for sure if the cab needs raising to get at the panels you need to remove in order to gain access to the electronics. Hopefully someone else will chime in.

Nige, thank you. That is a good confirmation for me. I was headed there but it's pretty dirty and such. Something just lost power over time, the dash lights would come on and beep but the more I turned them on and off it finally got to the point to where nothing comes on when I turn the key. The Battery is at 12.2 still.

Jeremy Sailee said:

The Battery is at 12.2 still.

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Just FYI. A fully charged battery in good condition should be around 12.8v

Got ya, well I had my tractor and jumper cables on it to charge it a bit more but that is plenty to get lights and turn it over. I get nothing when I turn the key now. Double checked all fuses today. I'm at a loss. Got to be something in the ECM interlock I think.

Jeremy Sailee said:

Got ya, well I had my tractor and jumper cables on it to charge it a bit more but that is plenty to get lights and turn it over. I get nothing when I turn the key now. Double checked all fuses today. I'm at a loss. Got to be something in the ECM interlock I think.

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Did you ever figure this out? My dash lights stopped working too. I've tried a lot of things...

Jeremy Sailee said:

Nige, thank you. That is a good confirmation for me. I was headed there but it's pretty dirty and such. Something just lost power over time, the dash lights would come on and beep but the more I turned them on and off it finally got to the point to where nothing comes on when I turn the key. The Battery is at 12.2 still.

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12.2 is way to low... 75 percent charge is 12.4.. 100% is 12.6. Are you placing the probes on the battery terminals or the battery cables when testing?

Need to do voltage drop testing of positive battery post to Starter positive post on the solenoid, as well as from positive battery post to main relay positive. These tests have to be done while attempting to start to be able to find out if 1 cable is bad internally. An ohms test will tell you nothing. Also need to test negative cables from battery to starter and to frame for voltage drop. You have changed out a lot of parts already, need to instead find a tech., who knows how to do these tests. You will not be able to tell if a cable is burn't off internally most of the time. Only a meter will tell you that.
Simon C