Hi all, newbie here. Working on my T190 which acted up on me. After sitting a week or 2 it wouldn't start. Turned the key on and the panel blinked repeatedly and would not quit. I could get the hour meter to display if I initiated a small electric load on the system first like turning on the lights. Went ahead and installed a new battery, one new cable and thoroughly cleaned connections. After more troubleshooting I found the feed for the "hold coil" on the fuel solenoid was receiving about 7.9 volts then would fall off to 5.6 after contact with the volt meter. This reading was with the ignition switch OFF. Disassembled the harness back to the ecu and when it was not plugged in it was fine and no voltage present in the harness. Plugging harness back into the ecu my voltage was back. I disconnected the battery and checked continuity between the hold coil pin "C1" and the unswitched power pins "A1-3" and was getting about 2.5 ohms. Guessing the box is bad but was wondering if a resident expert had seen this and knew something otherwise. Dealer wants $879.00 for the ecu plus labor to program it as well as time to troubleshoot it themselves. Thinking plan B may be to install wiring to manually activate fuel solenoid and starter and bypass that part of the system. Thanks in advance, Rick
Welcome to HEF RickinIA. :drinkup Is this a standard control machine, no ACS or AHC? What's the machine serial number?
Thanks for the reception and reply. This is a standard control machine and the serial number is 519311804. Has about 2355 hours on it right now. Thanks again, Rick
Ok, just wanted to make sure I was looking at the correct diagrams. First, I wouldn't condemn the main controller (ECU) unless I knew for certain (have eliminated all other possibilities) that it's bad. One thing about the Bobcat main controller, especially on standard control machines, that main controller is crazy durable and self protective, it has the ability to actually prevent malfunctions from making it go up in smoke. Yes, they can go bad, but that's more an exception than the rule. Pins A1 A2 and A3 at the J3 connector to the main controller, I assume that's the pins you referenced in your first post, on a s/n 519 T190, those three pins supply battery voltage to the main controller via fuse #4 (computer) in the fuse box. Have you put a volt meter on fuse #4 to see if that circuit maintains nominal 12V during various electrical loads on the system? If it does, have you verified A1 A2 and A3 maintains nominal 12V during various electrical loads?
Will check those first thing tomorrow. With the harness j3 off I had 12.3 volts at each "A" terminal and when reading with the harness connected they stayed at 12.3 and C1 would show 5.3 volts. All systems were off so I will verify readings with a load put on them. Do you think setting the parking brake and turning on the BICS will be sufficient? The fuse for the computer showed 12.3 as well on both sides of the terminal with the fuse inserted. Curious as to why there a 3 seperate 12 volt power inputs in this situation and does the hold coil circuit run on 12 volts or is it part of the 8 volt side? Thanks so much for your help with this.
Not a smooth start this morning. Plugged in all harnesses and went to test with a load and now have zero function with the ignition switch, absolutely dead. Voltage at fuse panel terminals and on the J3 connector but no response with the ignition switch. Still have the 5.6 volts going back to the fuel solenoid as well.
Machine lives. Started from scratch with the new problem and found the protected power from the ecu was losing voltage between the ecu and the cab harness connection. Traced wire as far as I could and didn't find the break so I ran a new wire from the ecu to the cab side harness and it seems to have fixed the problem. Still getting voltage to the fuel solenoid and I am a little confused by that, but the machine starts and turns off like it should so it must be a feature and not a bug. Thanks for all of your advice, if I had not gone back to put loads on it I may have never found the issue, your the man! Thanks again, Rick
Modern meters load the circuit so little that normal junction leakage on a switched output will show voltage, but not enough current there to light a test light, maybe not even an LED. Not sure why you're getting it with the switch off, but if the battery stays up, I wouldn't worry about it.
Check the harness connector where the cab harness meets up with the lower frame harness, it would be red or red/white wires at that connector. Take the connector apart and inspect the pins/sockets inside the connector for signs of corrosion or electrical arcing. And even trickier than that, I had a T300 dead on a jobsite once, pretty much same problem, lost power to the cab console, found power loss was at that harness connector, but it was not a problem with the pins/sockets inside the connector, turned out to be one of the red wires where it entered into the connector from the cab side, wasn't making a good connection with its socket inside the connector housing. Fitted a jumper wire for that red wire around the harness connector and it was off to the races.