I have a Caterpillar 246B Blows ECM1 fuse as soon as you hit the parking brake switch after starting. You can turn the ken on without starting and activate the parking brake all you would like too and the solenoid clicks just fine. Had to replace alternator few months ago it locked up replacement ended up being a cheap Chinese version that stated over charging at 17v, @ later I have that fixed and now the ecm fuse blows all the time I think its either the harness or possible the ECM, anyone herd of a problem like this. I have the Wiring diagram and will dive in tonight but its getting expensive just troubleshooting going through fuses.
A thermal breaker or trip can we wired into the fuse slot so you do not need to be replacing them constantly. More than likely the ECM was designed for over current and over voltage protection. I would check all of your ground connections as there could be feedback through ground.
Thanks for the advise, the thermal breaker helped a lot. I did find the problem it was the parking brake solenoid. Worked fine at 10v or under but apply more than 10v and it would draw too much current. The solenoid ohmed out at just over 2ohms ( Should be 10 +- 2) After removal I could see some plastic melted on the solenoid. For reference Cat Part number Solenoid 247-6462 has been discontinued and no longer available. Order instead 233-7131 Its the solenoid and valve attached. Don't forget the 6 o rings needed for the valve installation, Not sure why the discontinued the solenoid by it self they look the same it may be possible to just remove the new solenoid and reinstall in the old valve block but I didn't try. Old solenoid part number Manufacturers not cat 4303612 on new valve solenoid part number 4303612B
The part issue was in the valve block allowing oil to seep up and out of the solenoid electrical connection and losing full pilot pressure to the parking brakes . Make sure you check your engine wiring harness above the starter, around the top corners of the bellhousing and up to the main power breaker. They are notorious for wire rubs and causing a short to ground.
Thank you very much for the explanation, I had no clue why the part was changed and am now glad I fought my urge to just pull the solenoid off the new one and put it in the old one. I will also check the wiring harness in that location. At least for now everything is working great. Excuse my ignorance but lower pressure on the parking break what symptoms would that cause? I have always had a slight problem with the machine wanting to roll if it was parked on a incline even with the brake applied. However I thought this might be a separate issue. It wouldn't roll much just a few inches.
The parking brakes are spring applied, pressure released. If you start loosing pressure the parking brakes will not release. If the machine is rolling forward a few inches, you need to check the drive chain tension and inspect the drive motor mounting bolts to see if they have worked loose.