RENR5042-02 99 Troubleshooting Section D. Refer to Illustration 23. Place the red lead of the DVM on the diode at location (A). Place the black lead of the DVM on the diode at location (B). Expected Result: The test lamp illuminates. E. Measure the voltage drop across the diode. Results: Expected Result: OK The test lamp illuminated. The voltage drop across the diode is less than one volt. Repair: Replace the air shutoff relay. Verify that the problem is resolved. Results: STOP. OK The voltage drop across the diode is less than one volt. Proceed to Test Step 7. Not OK – The test lamp did not illuminate. Proceed to Test Step 9.
Not OK The voltage drop across the diode is greater than one volt. Test Step 9. Check the Voltage from the Keyswitch to the Air Shutoff Relay Repair: Replace the diode. Verify that the problem is resolved. A. Turn the keyswitch to the OFF position. STOP. B. Remove the wire from terminal R of the keyswitch. Test Step 7. Test the Diode for Current Flow in the Opposite Direction C. Turn the keyswitch to the ON position. D. Measure the voltage between terminal B of the keyswitch and engine ground. A. Reverse the locations of the leads for the DVM. E. Measure the voltage between terminal R of the keyswitch and engine ground. B. Measure the voltage drop across the diode. Expected Result: F.
Turn the keyswitch to the OFF position. The voltage drop across the diode is an OL. Expected Result: Results: Voltage is present on terminal B and terminal R at the keyswitch. OK – The voltage drop across the diode is an OL. Proceed to Test Step 8. Results: Not OK The voltage drop across the diode is less than one volt. OK – Voltage is present on terminal B and terminal R at the keyswitch. Repair: Replace the diode. Verify that the problem is resolved. 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 the original configuration. Verify that the problem is eliminated. STOP.
Test Step 8. Check the Voltage from the Keyswitch to the Normally Open Contacts of the Air Shutoff Relay STOP. Not OK – Voltage is not present on terminal B at the keyswitch. A. Turn the keyswitch to the OFF position. B. Disconnect the wire to the normally open contacts of the air shutoff relay from the keyswitch. Repair: If voltage is not present on terminal B, repair the wire between the +Battery and the keyswitch. Verify that the breaker is not tripped. Verify that the battery disconnect switch is operating correctly. Check the battery’s no-load voltage. Return all wiring to the original configuration. Verify that the problem is eliminated. C.
Connect the test lamp between the wire and engine ground. D. Turn the keyswitch to the ON position. STOP.