PUMP GP-GEAR 1297200 - Caterpillar

Illustration 7 g00761537
Diode leads
Table 3
Troubleshooting Test Steps Values Results
6. Test the Diode for the Control Circuit
A. Disconnect the air shutoff relay's control wires at the relay.
B. Remove the diode from the air shutoff relay.
C. Select the "Diode Check" function on a digital voltmeter.
D. Place the red lead of the digital voltmeter on the diode at location (A). Place the black lead of the digital voltmeter on the diode at location (B).
E. Measure the voltage drop across the diode.
Voltage Drop
Result: The voltage drop across the diode is less than one volt.
The voltage drop across the diode is OK. Proceed to Test Step 7.
Result: The voltage drop across the diode is greater than one volt.
Repair: The diode is damaged. Replace the diode. Verify that the problem is resolved.
STOP
7. Test the Diode for Current Flow
A. Reverse the position of the leads for the digital voltmeter.
B. Measure the voltage drop across the diode.
Voltage
Result: The digital voltmeter indicates an OL across the diode for this measurement.
The diode is OK. Proceed to Test Step 8.
Result: The digital voltmeter does not indicate an OL across the diode.
Repair: The diode is damaged. Replace the diode. Verify that the problem is resolved.
STOP
Illustration 8 g01165747
Location of the test lamp
Table 4
Troubleshooting Test Steps Values Results
8. Check the Voltage from the Keyswitch to the Voltage Input of the Air Shutoff Relay
A. Ensure that the keyswitch is in the OFF position.
B. Remove the wire at the voltage input of the air shutoff relay.
C. Connect the test lamp between the wire for the voltage input and the terminal for the voltage input at the air shutoff relay.
D. Turn the keyswitch to the ON position.
E.Check the test lamp.
F. Turn the keyswitch to the OFF position.
Test Lamp
Result: The test lamp illuminated.
Repair: The relay contacts are not passing the secondary voltage to the circuit for the air shutoff solenoid. Replace the air shutoff relay. Verify that the problem is resolved.
STOP
Result: The test lamp did not illuminate.
Input voltage is not reaching the relay. Proceed to Test Step 9.
9. Check the Harness between the Keyswitch and the Air Shutoff Relay
A. Turn the keyswitch to the OFF position.
B. Remove the wire from terminal R (keyswitch) of the keyswitch.
C. Turn the keyswitch to the ON position.
D. Measure the voltage between terminal B (+Battery) of the keyswitch and engine ground.
E. Measure the voltage between terminal R (keyswitch) of the keyswitch and engine ground.
F. Turn the keyswitch to the OFF position.
Voltage
Result: Voltage is present on terminal B and terminal R at the keyswitch.
Repair: If voltage is present on terminal R, repair the wire between the keyswitch and the air shutoff relay. Verify that the breaker is not tripped. Return all wiring to