0393742 JOHNSON OWNER'S MANUAL, Johnson

Use this procedure to troubleshoot the position sensors for the following valves:
EGR valve
Engine intake throttle valveEach position sensor is integral in the associated valve. If the following procedure indicates a fault with the position sensor, then the entire valve must be replaced.The following background information is related to this procedure:The troubleshooting procedures for the diagnostic codes of each position sensor are identical. The 5 VDC sensor supply provides power to all 5 VDC sensors. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM. The signal voltage from the valve position sensors is supplied to the appropriate terminal at the P1 or P2 ECM connector.Pull-up VoltageThe ECM continuously outputs a pull-up voltage on the circuit for the sensor signal wire. The ECM uses this pull-up voltage to detect an open in the signal circuit. When the ECM detects a voltage above a threshold, the ECM generates an open circuit diagnostic code (XXXX-3).If the sensor is disconnected, pull-up voltage indicates that the wires are not open or shorted to ground. The absence of pull-up voltage indicates an open in the signal wire or a short to ground. If the voltage is different from pull-up voltage, the signal wire is shorted to another wire in the harness.
Illustration 1 g06459004
Schematic diagram for the valve position sensors
Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Verify All Active and Recently Logged Diagnostic Codes
A. Turn the keyswitch to the ON position.
B. Use the electronic service tool to perform the "Air System Motor Valves Verification Test".
C. Verify if any of the diagnostic codes that are listed in Table 1are active or recently logged.
Diagnostic codes
Result: None of the preceding diagnostic codes are active or recently logged.
Repair: The fault may be intermittent. Refer to Troubleshooting, "Electrical Connectors - Inspect" to identify intermittent faults.
Result: One or more of the preceding diagnostic codes are active or recently logged.
Proceed to Test Step 2.
2. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the connector for the suspect valve and the engine interface connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".
B. Perform a 30 N (6.7 lb) pull test on each of the wires that are associated with the suspect position sensor in the valve connector and the engine interface connector.
C. Check the harness for abrasions and for pinch points from the suspect valve back to the ECM.
Note: Do not disconnect the ECM connector at this stage. The ECM can only be disconnected and reconnected 10 times before damage to the harness connector may occur.
Damaged wire or connector
Result: A damaged wire or damaged connector was found.
Repair: Repair the damaged wire or the damaged connector.
Use the electronic service tool to clear all logged diagnostic codes. 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 or of pinch points.
Proceed to Test Step 3.
3. Measure the Sensor Supply Voltage at the Valve Connector
A. Turn the keyswitch