66986 Mercruiser TERMINAL BLOCK, SHIFT BRACKET

The throttle switch uses resistors to modify the voltage signal from the ECM. The resistance of the switch changes dependent on which position the switch is in. The ECM uses the signal voltage to determine which mode has been selected.
Illustration 1 g03117957
View of the signal voltage range for the throttle switch
Illustration 2 g03734117
Typical example of the schematic for the throttle switch
Not all connectors are shown. Refer to the Electrical Schematic for the application.
Illustration 3 g02723018
Typical view of the pin locations on the P1 connector for the throttle switch
(55) Throttle switch signal
(77) Throttle switch ground
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the terminal connections on the P1/J1 connector.
B. Thoroughly inspect the connector for the throttle switch.
C. Refer to Troubleshooting, "Electrical Connectors - Inspect".
D. Perform a 30 N (6.7 lb) pull test on each of the wires in the connectors that are associated with the throttle switch.
E. Check the harness for abrasions and for pinch points from the switch back to the ECM.
Damaged wire or connector
Result: A damaged wire or damaged connector was not found.
Proceed to Test Step 2.
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.
2. Check for Active or Recently Logged 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. Do not start the engine.
D. Check for active diagnostic codes with the throttle switch in each position. Wait at least 10 seconds with the switch in each position for activation of the diagnostic codes.
Diagnostic Trouble Codes
Result: A 2880-4 diagnostic code is active.
Proceed to Test Step 3.
Result: A 2880-3 diagnostic code is active.
Proceed to Test Step 4.
Result: A 2880-2 diagnostic code is active.
Proceed to Test Step 5.
3. Create an Open Circuit at the Switch
A. Turn the keyswitch to the OFF position.
B. Disconnect the throttle switch.
C. Turn the keyswitch to the ON position.
D. Use the electronic service tool to check for an active 2880 diagnostic code. Wait at least 10 seconds for activation of the diagnostic codes.
E. Turn the keyswitch to the OFF position.
Diagnostic codes
Result: A 2880-3 diagnostic code is active with the switch disconnected.
Repair: Replace the throttle switch.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: A 2880-4 diagnostic code is still active with the switch disconnected.
Reconnect the switch and proceed to Test Step 7.
4. Create a Short at the Switch Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the throttle switch.
C. Fabricate a jumper wire and install the jumper wire between the two harness connector terminals for the throttle switch.
D. Turn the keyswitch to the ON position.
E. Use the electronic service tool to check for an active 2880 diagnostic code. Wait at least 10 seconds for activation of the diagnostic codes.
F. Turn the keyswitch to the OFF position.
G. Remove the jumper wire.
Diagnostic codes
Result: A 2880-4 diagnostic code is active with the jumper installed.
Repair: Replace the throttle switch.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: A 2880-3 diagnostic code is still active with the jumper installed.
Reconnect the throttle switch and proceed to Test Step 7.
5. Check the Voltage at the Switch Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the throttle switch.
C. Turn the keyswitch to the ON position.
D. Use a suitable multimeter to measure the voltage between the signal terminal and the ground terminal at the switch connector.
E. Turn the keyswitch to the OFF position.
4.9 V to 5.1 V
Result: The voltage is within the expected range.
Repair: Replace the throttle switch.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: The voltage is not within the expected range.
Proceed to Test Step 6.
6. Check the Wiring for High Resistance
A. Turn the keyswitch to the OFF position.
B. Disconnect the throttle switch. Disconnect the P1 connector.
C. Use a suitable multimeter to measure the resistance between the following points:
P1:55 to the signal terminal at the switch connector
P1:77 to the ground terminal at the switch connector
Less than 5 Ohms
Result: At least one of the resistance measurements is greater than 5 Ohms.
The fault is in the wiring between the switch connector and the P1 connector.
Repair: Check all wiring between the throttle switch and the ECM. Refer to the Electrical Schematic for the application.
Replace the faulty wiring.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: Both resistance measurements are less than 5 Ohms.
Proceed to Test Step 7.
7. Check the Wiring for a Short Circuit
A. Turn the keyswitch to the OFF position.
B. Disconnect the P1 connector from the ECM.
C. Disconnect the throttle switch.
D. Use a suitable multimeter to measure the resistance between the following points:
P1:55 and all other terminals on the P1 connector