70143 1 Mercruiser GASKET, CARBURETOR (MERCARB)

The following conditions must exist before any of the preceding codes will become active:
The ECM has been powered for at least 2 seconds.
There are no active 168 codes.
There are no active 3509 (262) codes.Use this procedure to troubleshoot the position sensors for the following valves:
NRS valve
Exhaust back pressure regulatorEach 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 ECM supplies 5.0 VDC to terminal "1" of both valve connectors. The sensor common from the ECM connector goes to terminal "2" of both valve connectors. 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 terminal "3" of both valves is supplied to the appropriate terminal at the 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 g06211980
Schematic diagram for the valve position sensors on C7.1 and C4.4 TA engine
Illustration 2 g06417520
Schematic diagram for the valve position sensors on C4.4 TTA engine
Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Turn the keyswitch to the OFF position.
B. Inspect the connectors for the valve position sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect".
C. Perform a 45 N (10 lb) pull test on each of the wires in the suspect sensor connector and the sensor connections at the ECM.
D. Check the screw for the J2 ECM connector for the correct torque of 6 N m (53 lb in).
E. Check the ground connection on the ECM for abrasions and pinch points.
F. Check the harness for abrasion and pinch points from the suspect sensor to the ECM.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring.
Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled.
Use the electronic service tool to clear all active diagnostic codes and verify that the repair eliminates the fault.
Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points.
Proceed to Test Step 2.
2. Check For Active Diagnostic Codes
A. Turn the keyswitch to the OFF position.
B. Connect the electronic service tool to the diagnostic connector.
C. Turn the keyswitch to the ON position. Wait at least 10 seconds for activation of the diagnostic codes.
D. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes.
E. Turn the keyswitch to the OFF position.
Diagnostic codes
Result: One or more of the preceding diagnostic codes are active or recently logged.
Proceed to Test Step 3.
Result: None of the preceding diagnostic codes are active or recently logged.
Repair: The fault may be intermittent. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Perform a "Wiggle Test" by using the electronic service tool to identify intermittent connections.
3. Measure the Supply Voltage at the Valve Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the suspect valve from the harness.
C. Turn the keyswitch to the ON position.
D. Measure the voltage between terminals 1 and 2 at the connector for the valve.
E. Reconnect the valve to the harness.
4.84 to 5.16 VDC
Result: The sensor supply voltage is out of the nominal range. The fault is in the engine harness between the valve connector and the ECM.
Repair: Repair the faulty valve connector or replace the faulty harness.
Use the electronic service tool to clear all active diagnostic codes and verify that the repair eliminates the fault.
Result: The sensor supply voltage i