85966A 1 Mercury CHOKE ROD ASSEMBLY

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Schematic for the injection actuation pressure sensorTest Step 1. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tool".
Turn the keyswitch to the ON position.Note:
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for an active 164-02 diagnostic code.Note: If a 164-03 Injector Actuation Pressure voltage high or 164-04 Injector Actuation Pressure voltage low code is active, refer to Troubleshooting, "Engine Pressure Sensor Open or Short Circuit - Test".Expected Result:The 164-02 diagnostic code is active.Results:
Active code - The 164-02 diagnostic code is active. Proceed to Test Step 3.
No active code - The 164-02 diagnostic code is not active. Proceed to Test Step 2.Test Step 2. Try to Start the Engine Try to start the engine.Expected Result:The engine starts.Results:
OK - The engine starts. There are no active codes for the injection actuation pressure sensor and the engine starts.Repair: There may be an intermittent problem in a harness that is causing the code to be logged. Refer to Troubleshooting, "Electrical Inspectors - Inspect".STOP
Not OK - The engine does not start.Repair: Refer to Troubleshooting, "Engine Cranks but Will Not Start".STOPTest Step 3. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Left side view (1) J500/P500 connectors for the injection actuation pressure sensor (2) J2/P2 connectors
Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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P2 terminals that are associated with the injection actuation pressure sensor (P2-17) Return (P2-72) +5 VDC (P2-85) Injection Actuation pressure
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Connectors for the injection actuation pressure sensor (A) Supply (B) Return (C) Signal
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the injection actuation pressure sensor.
Check the torque of the allen head screws for the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from the sensor back to the ECM.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 connectors and wiring are OK. Proceed to Test Step 4.
Not OK - There is a problem in the wiring and/or a connector.Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the problem is resolved.STOPTest Step 4. Check the Status of the Sensor
Turn the key switch to the ON position.
Check the value of the "Injection Actuation Pressure" on Cat ET.Note: The following codes will cause the value of the "Injection Actuation Pressure" to default to 17500 kPa (2538 psi).
164-03 Injector Actuation Pressure voltage high
164-04 Injector Actuation Pressure voltage lowExpected Result:The value of the "Injection Actuation Pressure" is 0 kPa (0 psi).Results:
OK - The value of the "Injection Actuation Pressure" is 0 kPa (0 psi). Proceed to Test Step 6.
Not OK - The value of the "Injection Actuation Pressure" is above 0 kPa (0 psi). Proceed to Test Step 5.Test Step 5. Check the Voltage Supply to the Injection Actuation Pressure Sensor
Turn the keyswitch to the OFF position.
Disconnect the J500/P500 connectors.
Connect a 3-terminal breakout T to the P500 harness connector only.
Turn the keyswitch to the ON position.
Measure the voltage between terminals A and B at the breakout T.Expected Result:The voltage reading is 5 0.2 VDC.Results:
OK - The voltage is within the specified range. Proceed to Test Step 6.
Not OK - The voltage is not within the specified range.Repair: Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test".STOPTest Step 6. Compare the Sensor's Output to a Pressure Gauge
Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact the skin.
Turn the keyswitch to the OFF position.
Install a 8T-0852 Pressure Gauge to an oil port on the side of the cylinder head or to the port on the top of the fuel transfer pump.
Start the engine.
Go to the "Injection Actuation Pressure Test" on the diagnostic menu of Cat ET.
Start the "Injection Actuation Pressure Test".
Refer to Table 1. Observe the value of the "Injection Actuation Pressure" on Cat ET. Vary the engine speed in order to obtain each "Injection Actuation Pressure" value that is listed in the Table. For each pressure value, observe the reading on the pressure gauge.
Table 1
Comparison of Pressure Readings    
"Injection Actuation Pressure" Values on Cat ET     Range of Acceptable Pressure Values on the Pressure Gauge    
6000 kPa (870 psi)     4000-7800 kPa (580-1130 psi)    
10000 kPa (1450 psi)     8000-11800 kPa (1160-1710 psi)    
15000 kPa (2175 psi)     13000-16800 kPa (1885-2435 psi)    
23000 kPa (3336 psi)     21000-24800 kPa (3045-3595 psi)