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Im working on a 939c track loader serial 6ds it wont start…

Im working on a 939c...
Im working on a 939c track loader serial 6ds it wont start at the switch I change the switch and the solenoid on the machine already when I hooked my start start swictch the one u hook to the power on the starter and the one that goes up to the switchit starts imedately I tested for power on the solenoid one has constant power and the other has power when u turn switch no power ran a wire from the starter to that solenoid still nothing what should I do the wire on cat diagram is 304 going from starter to solenoid tomorrow im gona change relay
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Answered in 1 minute by:
3/13/2014
Mechanic: catmastertech, Technician replied 8 years ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 3,997
Experience: Field service technician for CAT 19 years.
Verified

catmastertech :

Hello,

catmastertech :

Is this a Hystat machine?

catmastertech :

Have you check the circuit through the safety lever switch?

Customer:

Yes 6ds serial number

Customer:

were is the safety lever switch at

catmastertech :

The lever below the joystick control.

catmastertech :

It also releases the park brake.

catmastertech :

The switch is behind this cover and has four wires connected to it.

catmastertech :

The 306 green wire from the start position of the key switch is on terminal #2.

catmastertech :

This connects power to the start relay 374 pink wire at terminal #1.

catmastertech :

When the lever is down, the start relay should energize and send power down the 304 white wire to the starter solenoid.

Customer:

So got to test for power on that switch

catmastertech :

Yes. When the key switch is in the start position, the green wire should have power at the safety/neutral switch.

catmastertech :

The power must cross the switch when the lever is down. This is were the problem begins. The switch may fail and the power will not cross from the green wire to the pink wire.

Customer:

Ok ill look at that tomorrow so do u think I should change the starting relay and what are common problems that this happens

catmastertech :

The pink wire runs back to the dash and energizes the start relay. This will close the relay and send power to the 304 white wire.

catmastertech :

The 9X-4157 safety/neutral/park brake switch is the most common failure.

catmastertech :

You can test the circuit by placing the two wires together under the same terminal.

catmastertech :

It is a temporary fix only.

catmastertech :

Do not leave the wires together, this is a safety concern to prevent unintended movement.

catmastertech :

Leave the other two wires on the switch alone.

catmastertech :

The black and white wires are for the park brake control.

Customer:

Ok I check that tomorrow and for that ill get back at u and so where the parking brake lever is remove cover test power ok I was gona change this part tomorrow(NNN) NNN-NNNNbt ill hold off check that

catmastertech :

It is an easy check but, I have replace several switches.

catmastertech :

It is rarely the start rely behind the dash.

catmastertech :

OOPS -- relay

catmastertech :

I have replaced more starters than relays.

catmastertech :

I jump the green and pink wires or place them together to move the machine back to the shop. Then I order a switch and fix it the right way.

catmastertech :

If this does not get it to start, then check for power at the pink wire on the start relay behind the dash.

catmastertech :

If it does not have power, you may have damage to the wiring harness.

Customer:

Ok I check all that and talk u tomorrow thanks

catmastertech :

ok

catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 3,997
Experience: Field service technician for CAT 19 years.
Verified
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catmastertech
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 3,997
3,997 Satisfied Customers
Experience: Field service technician for CAT 19 years.

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