0320151 JOHNSON SOUND BLANKET

The ECM receives electrical power (battery voltage) through the wiring that is supplied by the manufacturer of the application. Battery+ voltage is supplied through P1:19.The battery- is supplied through the following terminals on the P1 connector:
P1:20
P1:39
P1:40
P1:59
P1:60
P1:79
P1:80The ECM receives the input from the keyswitch at P1:13 and P1:33 when the keyswitch is in the ON position or in the START position. When the ECM detects battery voltage at this input, the ECM will activate the main relay. When battery voltage is removed from this input, after a short time the ECM will deactivate the main relay.The cause of an intermittent power supply to the ECM can occur on either the positive side or on the negative side of the battery circuit. The connections for the unswitched battery+ may be routed through a dedicated protection device (circuit breaker).Some applications may be equipped with an engine protection shutdown system or an idle timer shutdown system that interrupts electrical power to the keyswitch. The engine protection shutdown system can be an aftermarket device and the idle timer shutdown system can be external to the ECM. Some of these systems will not supply power to the ECM until one of the following conditions is met:
The engine is cranking.
An override button is pressed.These devices may be the cause of intermittent power to the ECM. These devices may also shut down the engine.Usually, battery power to the diagnostic connector is available and the battery power to the data link connector is independent of the keyswitch. Therefore, although the electronic service tool can be powered up, there may be no communication with the engine ECM. The engine ECM requires the keyswitch to be in the ON position in order to maintain communications. The ECM may power down a short time after connecting the electronic service tool if the keyswitch is in the OFF position.
Illustration 1 g03681268
Schematic diagram of the electrical power supply circuit
Illustration 2 g03325729
View of the pin locations on the P1 connector for the ignition keyswitch and battery supply circuit
(3) Main relay -
(4) Main relay +
(12) Engine start signal
(13) Ignition keyswitch
(19) Battery +
(20) Battery ground
(23) Main relay -
(33) Ignition keyswitch
(39) Battery ground
(40) Battery ground
(59) Battery ground
(60) Battery ground
(79) Battery ground
(80) Battery ground
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Check the fuses.
B. Thoroughly inspect the battery connections and the connections to the keyswitch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the electrical power supply.
D. Check the harness for abrasion and for pinch points from the battery to the ECM, and from the keyswitch to the ECM.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring. A fuse is blown.
Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected. Replace any blown fuses.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, of abrasion and of pinch points. The fuses are OK.
Proceed to Test Step 2.
2. Check for Active Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Turn the keyswitch to the ON position.
C. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes or logged diagnostic codes.
Note: Wait at least 30 seconds for activation of the diagnostic codes.
Diagnostic codes
Result: A 1485-7 diagnostic code is active.
Proceed to Test Step 3.
Result: A 168-X or 3484-3 diagnostic code is active.
Proceed to Test Step 4.
Result: No diagnostic code is active.
If the fault is intermittent, refer to Troubleshooting, "Electrical Connector - Inspect".
If the ECM is receiving no battery power, proceed to Test Step 4.
3. Disconnect the ECM Main Relay
A. Turn the keyswitch to the OFF position.
B. Disconnect the ECM main relay. Disconnect the P1 connector from the ECM.
C. Use a suitable multimeter to measure the voltage between P1:19 and a suitable ground.
0 V
Result: The measured voltage is 0 VDC.
Reconnect the ECM main relay and recheck the voltage. If battery voltage is present, the ECM main relay is faulty.
Replace the ECM main relay.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: The measured voltage is greater than 0 VDC. There is a short in the wiring between the ECM main relay and the P1 connector.
Replace the faulty wiring.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
4. Check the Alternator
A. Test the alternator for correct operation. Refer to Systems Operation, Testing and Adjusting, "Alternator - Test".
Alternator
Result: The alternator is faulty.
Replace the alternator.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fau