PISTON 6Y2872 - Caterpillar

Illustration 3 g01151221
Pin locations on breakout T (48) Unswitched +Battery (52) Unswitched +Battery (53) Unswitched +Battery (55) Unswitched +Battery (63) −Battery (65) −Battery (67) −Battery (69) −Battery (70) Keyswitch
Disconnect the P1 ECM connector and insert a breakout T.Refer to Illustration 3 for the breakout T.
Measure the voltage between terminal 48 unswitched +Battery and terminal 63 -Battery.
Measure the voltage from terminal 52unswitched +Battery and terminal 65 -Battery.
Measure the voltage between terminal 53 unswitched +Battery and terminal 67 -Battery.
Measure the voltage between terminal 55 unswitched +Battery and terminal 69 -Battery.Refer to Illustration 3 for the breakout T.Perform Steps F, G, H, and I if 43-02 Key Switch Fault (71) is active or logged:
Disconnect P1 ECM connector and insert a breakout T.
Turn the keyswitch to the ON position.
Measure the voltage between P1-70 keyswitch and the following terminals:
P1-63
P1-65
P1-67
P1-69Expected Result:For 12 volt systems, the measured voltage is a constant 11.0 to 13.5 VDC with no suspected intermittent problems at this time.For 24 volt systems, the measured voltage is a constant 22.0 to 27.0 VDC with no suspected intermittent problems at this time.Results:
OK - The ECM is receiving the correct voltage. Repair: If an intermittent condition is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - Battery voltage out of range Proceed to Test Step 4.
Not OK - Intermittent voltage or no voltage Proceed to Test Step 5.
Not OK - Voltage for key switch out of rangeRepair: Trace the wiring for the keyswitch from the ECM through the keyswitch circuit to the batteries. Find the problem and repair the problem. Check the circuit protection for the circuit and the wiring. Refer to the vehicle service manual for instructions on troubleshooting the circuit for the keyswitch.Verify that the repairs eliminate the problem.STOPTest Step 4. Check the Batteries
Measure no-load battery voltage at the battery posts.
Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries" and Special Instruction, SEHS7633, "Battery Test Procedure".Expected Result:The batteries pass the load test. For 12 volt systems, the measured voltage is at least 11.0. For 24 volt systems, the measured voltage is at least 22.0.Results:
OK - Repair: Refer to the vehicle service manual for instructions on troubleshooting the vehicle wiring harness. Troubleshoot the vehicle wiring harness and repair the vehicle wiring harness, as required. Verify that the repairs eliminate the problem.STOP
Not OK - The batteries did not pass the load test.Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.STOPTest Step 5. Use the Bypass Harness for Cat ET to Bypass the Vehicle Wiring
Batteries give off flammable fumes which can explode.To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.
Do not connect the bypass harness to the battery until all of the in-line fuses have been removed from the +Battery line. If the fuses are not removed before connection to the battery, a spark may result.
Note: This