0326505 JOHNSON CYLINDER HEAD, Stbd., 90, 115

Table 1
Diagnostic Codes Table    
Diagnostic Codes Table     Conditions which Generate this Code     System Response    
168-0 Electrical System Voltage high - most severe (3)     The ECM reads battery voltage that is above 16 VDC.     The code is logged.    
168-1 Electrical System Voltage low - most severe (3)     The ECM reads battery voltage that is below 9 VDC.    
168-2 Electrical System Voltage erratic, intermittent, or incorrect     While the engine is running, the battery voltage drops below 9 VDC intermittently, or the battery voltage drops below 9 VDC three times in a seven second period.    Unswitched battery voltage is supplied through the customer connector to the ECM at P1-48, P1-52, and P1-53. The negative battery is supplied to the ECM at P1-61, P1-63, and P1-65. The ECM receives the input from the keyswitch at P1-70 when the keyswitch is in the ON position or the START position. When the ECM detects battery voltage at this input, the ECM will power up. When battery voltage is removed from this input, the ECM will power down.
Illustration 1 g01382599
Schematic diagram for the electrical power supply (typical wiring suggestion)Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Check for a tripped circuit breaker.
Illustration 2 g01214624
Location of the J1/P1 ECM connectors (typical engine view)
Thoroughly inspect the J1/P1 ECM connectors. Inspect the connections for the battery and the connections to the keyswitch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01378728
Terminal locations at the P1 ECM connector that are associated with the electrical power supply (P1-48) +Battery (P1-52) +Battery (P1-53) +Battery (P1-61) −Battery (P1-63) −Battery (P1-65) −Battery (P1-70) Keyswitch
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the electrical power supply.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from the battery to the ECM. Also, check the harness and wiring for abrasions and for pinch points from the keyswitch to the ECM.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.STOPTest Step 2. Check the Battery Voltage at the ECM
Disconnect the J1/P1 ECM connector.
Restore the electrical power to the ECM.
Turn the keyswitch to the ON position.
Measure the voltage between P1-52 (+Battery) and P1-63 (−Battery).
Measure the voltage between P1-48 (+Battery) and P1-61 (−Battery).
Measure the voltage between P1-53 (+Battery) and P1-65 (−Battery).
Measure the voltage between P1-70 (Keyswitch) and P1-63 (−Battery).Expected Result:The measured voltage is between 11.0 VDC and 13.5 VDC for a 12 volt system 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
Battery voltage is out of range - Proceed to Test Step 3.
Keyswitch voltage out of range - The voltage is not correct for the keyswitch circuit at the ECM. Proceed to Test Step 4.Test Step 3. Check the Condition of the Batteries
Measure the 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. The measured voltage is above the minimum specification for the batteries.Results:
OK - The batteries are OK.Repair: Check the wiring between the batteries and the ECM for shorts.Check the connectors between the batteries and the ECM for moisture and/or corrosion.Repair the wiring and/or the connectors.Verify that the repair eliminates the problem.STOP
Not OK - The battery voltage is low or the battery did not pass the load test.Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.STOPTest Step 4. Check the Voltages at the Battery and the Keyswitch
Remove electrical power from the ECM.
Remove the wire from the terminal R of the keyswitch.
Restore electrical power to the ECM.
Turn the keyswitch to the ON position.
Measure the voltage between terminal B of the keyswitch and engine ground.
Measure the voltage between terminal R of the keyswitch and engine ground.
Remove electrical power from the engine ECM.Expected Result:Voltage is present on terminal B and terminal R at the keyswitch.Results:
OK - Voltage is present on terminal B and terminal R at the keyswitch.Repair: Check continuity of wire J906-BR between the keyswitch and the ECM. Verify that the wire does not have a short or an open.STOP
Not OK - Voltage is not present on terminal B at the keyswitch.Repair: If voltage is not present on terminal B, repair the circuit between the +Battery and the keyswitch. Check the circuit protection for the circuit. Verify that the problem is eliminated.STOP
Not OK - Voltage is not present on terminal R at the keyswitch.Repair: If voltage is present on terminal B of the keyswitch but not present on terminal R, replace the keyswitch. Return all wiring to the original configuration. Verify that the problem is eliminated.STOP