Continuing saga of 753 traction lock

[henry]

This is where I am at now. Pulled solenoid again, made up set of jumpers to attach to plug on solenoid. Hooked ground to neg post of good battery, touched pull wire to pos post, solenoid picked up, touched hold wire to post, removed pull wire, solenoid held. Repeated a few times, solenoid worked fine. Hooked up jumpers to plug under seat .Sat in seat with solenoid in my lap, dropped seat bar,solenoid no work. Metered wires as I played with the seat bar. 13.3V on hold wire, .125 on pull wire. Looks like pull coil not getting enough voltage to pickup. Metered relay, 14.4V on line side of relay, waiting to go to pull coil , only 8.5 from BICS to relay. I don't think that is enough to close relay. Looking at wiring diagram, BCIS tells relay to close, sending juice to pull coil of solenoid. Voltage for hold coil comes directly from BCIS. Pondering how I checked voltage at relay, I wasn't in the seat with seat bar down. Wonder if that makes a difference? If it did, I would think there would not be any voltage from BCIS to realay at all, but I have 8.5. Any thoughts about all this? Where do I go from here?

 

[bremery]

I had the same problem for a while with my 763. I did the following three things.
1. Did you check the resistance of the traction lock coil resistance to see if it is in spec. When they go they will be way out of spec.
2. Did you swap the brake relay and glow plug relay. I cleaned all contacts when I did mine. If the problem goes away you probably have a bad relay.
3. Check and clean the fuses that are powered on that circuit.

 

[henry]

I had the same problem for a while with my 763. I did the following three things.
1. Did you check the resistance of the traction lock coil resistance to see if it is in spec. When they go they will be way out of spec.
2. Did you swap the brake relay and glow plug relay. I cleaned all contacts when I did mine. If the problem goes away you probably have a bad relay.
3. Check and clean the fuses that are powered on that circuit.

Yep-did all that. All the lights on the BICS panel are on. ohms on coils are .3 and 10.5 I was planning to recheck the relays again, just to make sure.

 

[bremery]

Yep-did all that. All the lights on the BICS panel are on. ohms on coils are .3 and 10.5 I was planning to recheck the relays again, just to make sure.

Do you get any flashing lights on the bics? Did you check the main ground for the BICS? It would be under the cab, behind your left sholder if you were sitting in the machine. Sometimes these corrode, and you won't get a good ground.
Do you have a parking brake switch by your right foot? Did you try disconnecting it and see if it helps. It a two wire harness, again acessible by lifting the cab, right near the parking brake solenoid. If the wire gets it can cause problems.
It make be worth cleaning the batter connections too, and make sure your alternator is putting out the correct voltage. These are quick and easy things to do to cross them off the list.

 

[henry]

Do you get any flashing lights on the bics? Did you check the main ground for the BICS? It would be under the cab, behind your left sholder if you were sitting in the machine. Sometimes these corrode, and you won't get a good ground.
Do you have a parking brake switch by your right foot? Did you try disconnecting it and see if it helps. It a two wire harness, again acessible by lifting the cab, right near the parking brake solenoid. If the wire gets it can cause problems.
It make be worth cleaning the batter connections too, and make sure your alternator is putting out the correct voltage. These are quick and easy things to do to cross them off the list.

Did all that also I have a good ground from solenoid plug to ground, no BICS flashing lights, alternator is putting out 14.4V, parking brake switch is disconnected.No mice chewing on wires. I did not pull and clean the plugs yet. Solenoid had sporadic problems, now will not pick up at all. Everthing points to this thing working, but,,that is not my luck.

 

[mrfixitpaul]

Did all that also I have a good ground from solenoid plug to ground, no BICS flashing lights, alternator is putting out 14.4V, parking brake switch is disconnected.No mice chewing on wires. I did not pull and clean the plugs yet. Solenoid had sporadic problems, now will not pick up at all. Everthing points to this thing working, but,,that is not my luck.

Check for corroded fuses, sometimes they'll corrode inside and allow voltage until the load is too high, then lose the power, then allow power again when the load is reduced. If the solenoid works outside the machine but not when in place, check that the 1/4 inch bolt on the bottom of the plunger is not grooved, as this can bind up the plunger and prevent proper operation.