I have a 2001 bobcat 773 g series skid steer with about 1300 hrs on it. I have a reoccurring problem with losing the seat bar light and locking everything down abruptly. Sometimes the seat bar light will come right back on and back to normal. No codes are present. I have changed the battery, alternator, checked all plug connections, shaken all wires checking for loose connections, checked all visible ground connections, taken the seat bar sensor apart and manually checked it, checked the plug going to the seat bar sensor, checked fuses and relays, taken connections apart from computer and replaced, and checked the plug in the back of BICS. The problem is still occurring randomly. Sometimes it is worse than others. The seat bar light will come on and go off whether the machine is running or when the key is just turned on. One thing I have noticed is that when I lose the seat bar light the temperature hand on the BICS will start rising. As soon as the seat bar light comes back on the temp hand will return to normal. Some mechanics are telling me bare wires or bad computer. Any suggestions or ideas will be greatly appreciated!!!
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Bobcat 773 G electrical issue
- Thread starter Elo
- Start date
willie59
Administrator
Welcome to HEF Elo. :drinkup
That's a tricky problem you got there, and I don't have an answer for you for that reason. I can say that the seat bar switch is on a circuit that is independent (not related) to the temp gauge. If that temp gauge does in fact move up or down when seat bar circuit is acting up then there is a curious correlation. The three wires from the seat bar switch leave the switch and join up with the wires in the main cab harness then go straight to the ECM. The ECM sends data link information through that harness to the left and right control panels in cab, but that circuit has no direct link or connection to the seat bar switch. If a correlation of the two circuits does in fact exist, then there would have to be a problem in the main harness from cab to ECM or a faulty ECM.
Before I condemn the ECM, I would look closely at all points of that cab harness going to ECM, especially any point of the harness from the point the seat bar switch wires join the harness and continue to the ECM. Take a close look at that connector where the cab harness meets the frame harness located above the hydraulic reservoir. Take that connector apart and check the pins/sockets closely looking for abnormalities or corrosion. Check all points of the harness for chaffing of wires. Also check the ground cable that grounds cab to main frame, it's a fairly heavy gauge wire that runs along side of the cab harness at back of cab when cab is raised.
That's a tricky problem you got there, and I don't have an answer for you for that reason. I can say that the seat bar switch is on a circuit that is independent (not related) to the temp gauge. If that temp gauge does in fact move up or down when seat bar circuit is acting up then there is a curious correlation. The three wires from the seat bar switch leave the switch and join up with the wires in the main cab harness then go straight to the ECM. The ECM sends data link information through that harness to the left and right control panels in cab, but that circuit has no direct link or connection to the seat bar switch. If a correlation of the two circuits does in fact exist, then there would have to be a problem in the main harness from cab to ECM or a faulty ECM.
Before I condemn the ECM, I would look closely at all points of that cab harness going to ECM, especially any point of the harness from the point the seat bar switch wires join the harness and continue to the ECM. Take a close look at that connector where the cab harness meets the frame harness located above the hydraulic reservoir. Take that connector apart and check the pins/sockets closely looking for abnormalities or corrosion. Check all points of the harness for chaffing of wires. Also check the ground cable that grounds cab to main frame, it's a fairly heavy gauge wire that runs along side of the cab harness at back of cab when cab is raised.
Thanks Willie! I unplugged the connector you are talking about earlier but I forgot to mention that. There was a silicone like substance inside the plug to prevent moisture but all looked normal. I cleaned that ground a few days ago and made sure it was tight. It is hard to check the wires thoroughly because of the factory web-like coating around the wires. I'm afraid it is going to be an ECM problem. Is there any way to check that other than replacing the ECM?
willie59
Administrator
That I don't know, sorry. Maybe Bobcat can offer some advice there. I do hope you find a solution to your problem. 
another possibility is a short in the door switch wiring - even if there never was a door. I doubt it's an ECM problem but could get it flashed perhaps. The Bobcat Electronics Manual is pretty good with helping to diagnose issues without codes.
mountainlake
Well-Known Member
Really check out all of the ground connections, bad grounds cause lots of problems. Steve
crewchief888
Senior Member
the seat bar switch is on the same 8v supply circuit as all the rest of the sensors, as well as the RH aux paddle switch.
on early g series machines any of the sensors, wiring or connectors could be causing a problem with another sensor
if any of the plastic bushings for the seat bar sensor are worn, the same thing can happen.
also check the terminal sockets inside the connector to the seat bar switch, one or more may be slightly spread open, causing an intermittent contact
on early g series machines any of the sensors, wiring or connectors could be causing a problem with another sensor
if any of the plastic bushings for the seat bar sensor are worn, the same thing can happen.
also check the terminal sockets inside the connector to the seat bar switch, one or more may be slightly spread open, causing an intermittent contact