Underachiever
Member
- Joined
- Dec 21, 2021
- Messages
- 6
S/N: 515833555
I need some troubleshooting guidance with my 753G. I'm not sure of the year. It has about 1950 hours. I've had it several years but haven't put many hours on it. Up until now it's been reliable.
I tried to run it a few weeks ago and it cranked but wouldn't acknowledge the seat bar and subsequently engage the hydraulics. I messed with it for a while until my weak aged battery gave up the ghost. I put a new battery in and got it to crank right up and it started beeping with the hydraulic indicator and shutting off with code 05-15. I got to looking at the engine compartment and noticed out of maintenance schedule hours written on all the filters and decided to change them as well as the engine oil. I changed the engine oil. No idea what was in it but I put back Rotella 10W-30 synthetic blend. I changed the oil filter, the fuel filter and the hydraulic filter. When I cranked it back up I started getting some beeping and the engine oil and hydraulic indicators and then shutting off with codes 04-15 and 05-15. At this point I guessed that maybe I had at least one bad sensor and ordered a replacement for each. I got the oil pressure sensor first. I put it on and the oil indication light stayed off but still would get the hydraulic light and engine shutoff which was sometimes sporadic. Sometimes the engine would run for a while without fault but the seat bar sensor would never be made. I got to looking at the seat bar sensor and saw it was cracked at the connection point. I took all that apart and ordered a seat bar sensor. I got that and the hydraulic pressure sensors put on and I'm still getting the 05-15 and engine shutoff (most of the time). Its still not engaging the hydraulics nor is the seat bar indicator ever being made.
I got to looking at the electrical schematics and saw that for both the engine oil and hydraulic sensors that the computer supplies 7.5V across a positive and battery ground wire and a 3rd wire carries the signal back to the computer. I turned the ignition switch on but didn't crank the engine. I then pulled the connectors off both the hydraulic and engine oil sensors and measured across the computer positive and battery negative wires in the sensor connector and got 2.5V at both.
I'm guessing in this state I should be seeing 7.5V across those 2 wires. I've taken the grounds loose at the big wiring harness in the engine compartment and didn't really see any problems. I cleaned them up anyway and put them back on. I made sure the battery connections were clean and tight. I've looked through the wiring as it enters under the cab to the computer and so far haven't found any pinched, nicked or exposed wiring. I'm beginning to wonder if the computer has crapped out.
Short of trying to get a Bobcat tech out with a diagnostic computer I was wondering if anyone had any ideas about what I could check? I'm not super familiar with Bobcat engines but I have a decent electrical background.
Sorry for the long novel but I figure there's never too much info. I appreciate any help.
I need some troubleshooting guidance with my 753G. I'm not sure of the year. It has about 1950 hours. I've had it several years but haven't put many hours on it. Up until now it's been reliable.
I tried to run it a few weeks ago and it cranked but wouldn't acknowledge the seat bar and subsequently engage the hydraulics. I messed with it for a while until my weak aged battery gave up the ghost. I put a new battery in and got it to crank right up and it started beeping with the hydraulic indicator and shutting off with code 05-15. I got to looking at the engine compartment and noticed out of maintenance schedule hours written on all the filters and decided to change them as well as the engine oil. I changed the engine oil. No idea what was in it but I put back Rotella 10W-30 synthetic blend. I changed the oil filter, the fuel filter and the hydraulic filter. When I cranked it back up I started getting some beeping and the engine oil and hydraulic indicators and then shutting off with codes 04-15 and 05-15. At this point I guessed that maybe I had at least one bad sensor and ordered a replacement for each. I got the oil pressure sensor first. I put it on and the oil indication light stayed off but still would get the hydraulic light and engine shutoff which was sometimes sporadic. Sometimes the engine would run for a while without fault but the seat bar sensor would never be made. I got to looking at the seat bar sensor and saw it was cracked at the connection point. I took all that apart and ordered a seat bar sensor. I got that and the hydraulic pressure sensors put on and I'm still getting the 05-15 and engine shutoff (most of the time). Its still not engaging the hydraulics nor is the seat bar indicator ever being made.
I got to looking at the electrical schematics and saw that for both the engine oil and hydraulic sensors that the computer supplies 7.5V across a positive and battery ground wire and a 3rd wire carries the signal back to the computer. I turned the ignition switch on but didn't crank the engine. I then pulled the connectors off both the hydraulic and engine oil sensors and measured across the computer positive and battery negative wires in the sensor connector and got 2.5V at both.
I'm guessing in this state I should be seeing 7.5V across those 2 wires. I've taken the grounds loose at the big wiring harness in the engine compartment and didn't really see any problems. I cleaned them up anyway and put them back on. I made sure the battery connections were clean and tight. I've looked through the wiring as it enters under the cab to the computer and so far haven't found any pinched, nicked or exposed wiring. I'm beginning to wonder if the computer has crapped out.
Short of trying to get a Bobcat tech out with a diagnostic computer I was wondering if anyone had any ideas about what I could check? I'm not super familiar with Bobcat engines but I have a decent electrical background.
Sorry for the long novel but I figure there's never too much info. I appreciate any help.
