773G Electrical problem, need some advice

[oldironcollector]

I have a 773G turbo that started acting weird and it has gotton worse over the last week or so. It all started with a no start condition, spin spin spin, no start. I checked the fuel shut off solenoid and helped it pull over and it stayed so it started right up. Repeat the same procedure several times when I had to turn the machine off. I checked and had 7.8 V on both the pull in and hold side of the solenoid. arrgh. Parked the machine and onto other things. Then several days later I went to pull it out of the barn to get it to the garage to do some diagnostics and insert key turn switch roars to life no problem. Drop the seat bar to move the machine and no acknowledgement lights on the indicator panel and machine will not move. Pulled the connector on the seat bar loose and checked 7.8 volts on one the terminals. I have a service manual and it is about a useless as 10 horns on a billie goat when it comes to electrical diagnostics. It does not provide any specs as to voltage input or outputs of the bcis controller. In an automotive setting a 5v ref is used to sensors and switches but I don't have a clue with the bobcat system. It sounds like a voltage drop situation some where but I have not been able to pinpoint it. With the lap bar it gives a part number for a Bobcat brand tester to bypass it. Any idea on the breakdown electrically of the lapbar sensor? It has 3 wires. I have some metripak connectors that I can make up a test jig with. Or anyone out there experience a simiular problem? Thanks for any anticipated help!

 

[oldironcollector]

Forgot to add no codes in the BCIS computer

 

[skidsteer.ca]

Forgot to add no codes in the BCIS computer

First off change out any spdt relays in the fuse panel, these are wear parts like a starter solinoid.
There will be one for starter, and main power, glow plugs and park brake
Ken

 

[Tazza]

Forgot to add no codes in the BCIS computer

The voltage at the pull and hold coils should be 12v, not 7.8v.
It sounds like you may have a bad ground or bad connector somewhere making you have low voltage at the coil. If its low, it won't have the power to pull the plunger to seat, thats why when you moved it by hand it seated, it had enough power to hold it there, but not enough to pull it into place to start with.
I'd start there.

 

[oldironcollector]

The voltage at the pull and hold coils should be 12v, not 7.8v.
It sounds like you may have a bad ground or bad connector somewhere making you have low voltage at the coil. If its low, it won't have the power to pull the plunger to seat, thats why when you moved it by hand it seated, it had enough power to hold it there, but not enough to pull it into place to start with.
I'd start there.

Ok, thanks for the input everyone, I have the starting part handled but still no acknowledgement from the seat bar sensor. Checked and have 8 volts to the sensor on 2 pins and ground on the third pin. Took the seat bar off and removed the sensor and ohmed it out and it makes no difference where the magnets are positioned, there is no change in the ohm readings of open circuit. looked up the sensor and came up with a Bobcat PN 6674406. Anybody ever bought one and have an idea of pricing? Everyone is closed here and I tryed finding some on line pricing but no avail. Just curious about cost. Thanks Denny

 

[Tazza]

Ok, thanks for the input everyone, I have the starting part handled but still no acknowledgement from the seat bar sensor. Checked and have 8 volts to the sensor on 2 pins and ground on the third pin. Took the seat bar off and removed the sensor and ohmed it out and it makes no difference where the magnets are positioned, there is no change in the ohm readings of open circuit. looked up the sensor and came up with a Bobcat PN 6674406. Anybody ever bought one and have an idea of pricing? Everyone is closed here and I tryed finding some on line pricing but no avail. Just curious about cost. Thanks Denny

The sensor is a haul effect type, its not simply a switch, so its hard to know when its working or not. If you have a seat sensor, you can try moving that one and see if the problem goes away. I can't see a new one being that expensive either.

 

[oldironcollector]

The sensor is a haul effect type, its not simply a switch, so its hard to know when its working or not. If you have a seat sensor, you can try moving that one and see if the problem goes away. I can't see a new one being that expensive either.

UPDATE: Ordered a seat bar sensor $35.00 replaced it and all is well. I guess sometimes I look for the worse but it's just habit I guess. Thanks for everyones advice and comments!!!