0436865 JOHNSON CARBURETOR ASSY.

Illustration 1 g00676428
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect ECM connector J1/P1, ECM connector J2/P2, machine connector J3/P3, and all other connectors in the wiring harness. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Engine Fan Speed on ET
Connect ET to the service tool connector.
Start the engine. Ensure that the keyswitch is in the ON position.
Compare the status for "Engine Fan Speed" to the status for "Desired Engine Fan Speed" on ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:"Engine Fan Speed" should be within 50 rpm of "Desired Engine Fan Speed".Results:
OK - The sensor is operating correctly.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - Proceed to Test Step 3.Test Step 3. Check the Digital Sensor Supply Voltage at the Sensor Connector
Disconnect fan speed sensor connector J84/P84.
Turn the keyswitch to the ON position.
Measure the voltage across P84:A (+8 VDC) and P84:B (Ground).
Turn the keyswitch to the OFF/RESET position.Expected Result:The digital sensor supply voltage should be 8.0 0.5 VDC.Results:
OK - The supply voltage is reaching the sensor. Proceed to Test Step 5.
Not OK - The supply voltage is not reaching the sensor. Proceed to Test Step 4.Test Step 4. Check for Shorts in the Harness From the Fan Speed Sensor to ECM Connector J1/P1
Illustration 2 g00676466
ECM connector P1
Disconnect ECM connector J1/P1.
Disconnect fan speed sensor connector J84/P84.
Measure the resistance between P1:35 (Digital Sensor +8 VDC) and chassis ground.
Measure the resistance between P1:35 (Digital Sensor +8 VDC) and P1:29 (Digital Sensor Return).
Measure the resistance between P2:25 (Fan Speed Sensor) and P1:29 (Digital Sensor Return).
Measure the resistance between P1:35 (Digital Sensor +8 VDC) and P2:25 (Fan Speed Sensor).Expected Result:The resistance for each measurement should be greater than 20,000 Ohms.Results:
OK - Proceed to Test Step 6.
Not OK - There is a short between the ECM and the fan speed sensor.Repair: Repair the circuit.STOPTest Step 5. Check for Shorts in the Harness From the Fan Speed Sensor to ECM Connector J2/P2
Illustration 3 g00676834
ECM connector P2
Disconnect ECM connector J2/P2.
Disconnect fan speed sensor connector J84/P84.
Measure the resistance between P2:25 (Fan Speed Sensor) and chassis ground.
Measure the resistance between P2:25 (Fan Speed Sensor) and P1:29 (Digital Sensor Return).
Measure the resistance between P1:35 (Digital Sensor +8 VDC) and P2:25 (Fan Speed Sensor).Expected Result:The resistance for each measurement should be greater than 20,000 Ohms.Results:
OK - Proceed to Test Step 7.
Not OK - There is a short between the ECM and the fan speed sensor.Repair: Repair the circuit.STOPTest Step 6. Check for Open Circuits in the Harness From the Fan Speed Sensor to ECM Connector J1/P1
Illustration 4 g00676466
J1/P1 breakout
Turn the keyswitch to the OFF/RESET position and install a 7X-1715 Adapter Cable (40 Pin Breakout) at ECM connector J1/P1.
Use a suitable piece of wire to short P1:35 (Digital Sensor +8 VDC) and P1:29 (Digital Return) at the breakout.
Disconnect fan speed sensor connector J84/P84.
Measure the resistance between P84:A (+8 VDC) and P84:B (Ground).Expected Result:The resistance should be less than 10 Ohms.Results:
OK - Proceed to Test Step 8.
Not OK - There is an open circuit in the wiring harness between the fan speed sensor and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 7. Check for Open Circuits in the Harness From the Fan Speed Sensor to ECM Connector J2/P2
Illustration 5 g00676834
ECM connector P2
Disconnect ECM connector J2/P2.
Disconnect fan speed sensor connector J84/P84.
Measure the resistance between P84:C (Signal) and P2:25 (Engine Fan Speed).Expected Result:The resistance should be less than 8 Ohms.Results:
OK - Proceed to Test Step 8.
Not OK - There is an open circuit in the wiring harness between the fan speed sensor and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 8. Check the Digital Sensor Supply Voltage at the ECM
Illustration 6 g00676466
J1/P1 breakout
Turn the keyswitch to the ON po