888590002 Mercury SENSOR

Table 1
Diagnostic Codes Table    
Code    Conditions which Generate this Code    System Response    
168-0 Electrical System Voltage high - most severe (3)     The battery supply voltage is greater than 32 VDC for two seconds.
The engine's ECM has been powered for three seconds.
The engine is not being cranked.     The code is logged.    
168-1 Electrical System Voltage low - most severe (3)     The battery supply voltage is less than nine VDC for two seconds.
The engine's ECM has been powered for three seconds.
The engine is not being cranked.    
168-2 Electrical System Voltage erratic, intermittent, or incorrect     The engine is running. The battery voltage falls below nine VDC for at least .06 seconds. The voltage returns above nine VDC.
or
Three voltage readings in the last seven seconds were below nine VDC.     If the engine is running, the code is logged.    Use this test if there are intermittent engine shutdowns or if a difficulty in starting is not accompanied by loss of electrical accessories. Engine shutdowns that are accompanied by a loss of other electrical accessories indicate a problem in the keyswitch. This does not indicate a problem in the wiring at the ECM. Verify that there are no problems with the starting system or with the charging system before you use this test.There is a +Battery connection and a −Battery connection to the ECM. The ECM receives battery voltage through the main relay and a 15 amp fuse. When the keyswitch is in the ON position, the main relay is energized and the ECM is powered. When the keyswitch is in the OFF position, the ECM is not powered and the ECM turns off.
Illustration 1 g01454126
Typical schematic
Illustration 2 g01454559
P1 ECM connector (5) Engine ground (6) Switched +BatteryTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Turn the circuit breaker for the battery to the OFF position.
Illustration 3 g01139425
ECM (1) J1/P1 connectors (2) J2/P2 connectors
Thoroughly inspect the ECM connector J2/P2. Inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and the wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/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.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Battery Voltage
Measure no-load battery voltage at the battery terminals. Refer to Testing and Adjusting, "Test Tools for the Electrical System" for the proper procedures to check the batteries.
Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to the Operating Manual, SEHS9249. Refer to Special Instruction, SEHS7633.Expected Result:The no-load voltage at the batteries is at least 23.5 VDC and the batteries pass the load test.Results:
OK - The battery voltage is OK and the battery passes the load test. Proceed to Test Step 3.
Not OK - The battery voltage is incorrect and/or the battery fails the load test.Repair: The batteries or the alternator are causing the problem. Recharge the batteries or replace the batteries. Verify that the original condition is resolved. Refer to Systems Operation/Testing and Adjusting, "Electrical System".STOPTest Step 3. Check the Voltage at the ECM
Remove ECM connector P1.
Turn the circuit breaker for the battery to the ON position.
Turn the keyswitch to the ON position.
Measure the voltage between P1-6 and P1-5.Expected Result:The voltage measures 24 3.0 VDC.Results:
OK - The voltage measures 24 3.0 VDC. The voltage at the ECM is OK.Repair: The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The voltage is not 24 3.0 VDC. The voltage is not correct at the ECM. Verify that wire 200-BK has continuity to engine ground. If wire 200-BK does not have continuity to engine ground, repair the wire. If wire 200-BK is OK, proceed to Test Step 4.Test Step 4. Check the Voltage from the Main Relay to the ECM
Turn the keyswitch to the OFF position.
Disconnect wire 112-PU from the normally open contact of the main relay.
Turn the keyswitch to the ON position.
Check the voltage between the normally open contact of the main relay and engine ground.
Turn the keyswitch to the OFF position.
Return all wires to the original configuration.Expected Result:The voltage measures 24 3.0 VDC.Results:
OK - The voltage is 24 3 VDC.Repair: Check that fuse "ECM" is not open. Check the wire 112-PU between the main relay and fuse "ECM" for an open or short. Check the wire 123-WH between the fuse "ECM" and the ECM connector P1-6 for an open or short. Make any repairs that are needed.STOP
Not OK - The voltage is not 24 3 VDC. Proceed to Test Step 5.Test Step 5. Check the Voltage from the Keyswitch to the Main Relay
Remove the wires from terminal R of the keyswitch.
Turn the keyswitch to the ON position.
Measure the voltage on terminal B of the keyswitch to engine ground.
Measure the voltage on terminal R of the keyswitch to engine ground.
Turn the keyswitch to the OFF position.
Return all wires to the original configuration.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. Proceed to Test Step 6.
Not OK - Voltage is not present on terminal B at the keyswitch.Repair: If voltage is not present on terminal B, repair the circuit that is between the