GEAR (55 teeth) 6P2776 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the power to the engine Electronic Control Module (ECM). Also use this procedure if any one of the diagnostic codes in Table 1.
Table 1
Diagnostic Trouble Codes
CDL Code and Description Comments
111–2
Engine Coolant Level Sensor : Erratic, Intermittent, or Incorrect The engine is running. The battery voltage falls below 6 VDC and the voltage returns above 9 VDC for three voltage readings in the last 7 seconds.
1834-2
Ignition Key Switch loss of signal The ECM detects an erratic signal from the keyswitch because the keyswitch was cycled at least three times in the last second
168-0
Electrical System Voltage : Voltage Above Normal The ECM detects voltage that is above the acceptable value.
168-1
Electrical System Voltage : Voltage Below Normal The ECM detects voltage that is below the acceptable value.
168-2
Electrical System Voltage : Erratic, Intermittent, or Incorrect The engine is running. The battery voltage falls below 6 VDC and the voltage returns above 9 VDC for three voltage readings in the last 7 seconds.
Illustration 1 g02154189Probable Causes
Codes
Electrical connectors
Wiring
Charging circuit
Battery chargeRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Establish communication between the Cat® Electronic Technician (ET) and the ECM.
B. Start the engine. Run the engine until the engine is at normal operating temperature.
C. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. Check for the codes listed below:
168-2
168-0
168-1
1834-2
Codes
Result: A 168-2 or a 1834-2 diagnostic code is active.
Proceed to Test Step 2.
Result: A 168-0 diagnostic code is active.
Proceed to Test Step 3.
Result: A 168-1 diagnostic code is active.
Proceed to Test Step 4.
2. Inspect the Electrical Connectors and the Wiring For the Charging Circuit
A. Turn the keyswitch to OFF.
B. Check the harness connections at the battery and at the alternator.
C. Check the harness between the battery and the alternator.
Connectors and Wiring
Result: The harness and connectors are OK. There is a problem with the charging system.
Repair: Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
Result: The connectors and/or wiring are not OK.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminates the problem.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Charging Circuit
A. Check the charging circuit. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
Charging Circuit
Result: The charging system is OK.
Proceed to Test Step 4.
Result: The charging system is not OK.
Repair: Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
If the problem is not resolved, proceed to Test Step 4.
4. Check the Battery Charge
A. Measure the no-load battery voltage at the battery posts.
B. 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 V and 12 V Lead Acid Batteries" and Special Instruction, SEHS7633, "Battery Test Procedure".
Battery Charge
Result: The batteries are OK.
Repair: 1. Verify that the "System Operating Voltage Configuration" is correctly configured in the engine ECM