5E32900TP Mercruiser STERNDRIVE, Bravo-I XR Diesel (1.35:1)

Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
96-8 Fuel Level Sensor : Abnormal Frequency, Pulse Width, or Period     The signal for the fuel level sensor is intermittent or the signal has been lost.     The code is logged.    The fuel level sensor is a passive sensor. The fuel level sensor does not require an operating voltage in order to provide a signal. This configuration utilizes a fuel level buffer that helps to reduce the amount of indicator movement that is passed to the fuel gauge. The buffer is powered through a circuit that is wired directly to a circuit breaker.When the fuel tank is full, the fuel level sensor has a resistance of 0 to 3.5 Ohms. When the fuel tank is empty, the fuel level sensor has a resistance of 92 to 98 Ohms. The resistance from the fuel level sensor varies between these values as the fuel level varies.An active diagnostic code for the fuel level sensor is probably caused by a problem in the wiring harness. The next likely cause is a problem with the fuel level sensor. The least likely cause is a problem with the Electronic Control Module (ECM).
Illustration 1 g01717513
Schematic for the fuel level sensorTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the J1/P1 ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 2 g01176464
P1 terminals that are associated with the fuel level sensor (P1-68) Fuel level sensor signal (P1-5) Sensor return
Illustration 3 g01155187
Fuel level sensor connector (1) Fuel level (2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel level sensor.
Check the allen head screw on the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the fuel level sensor to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or the wiring.Repair: Repair the circuit. Verify that the repair eliminates the problem.STOPTest Step 2. Confirm the Fuel Level in the Tank
Visually check the fuel level in the tank.
Compare the fuel level in the tank to the indicator on the fuel level sensor.Expected Result:The fuel level in the tank agrees with the indicator on the fuel level sensor.Results:
OK - Repair: The fuel level sensor appears to be operating correctly at this time. There may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - The indicator on the fuel level sensor does not reflect the actual fuel level in the tank. Proceed to Test Step 3.Test Step 3. Check the Resistance of the Fuel Level Sender
Disconnect the fuel level sensor from the fuel level buffer.
Measure the resistance between the terminals on the receptacle for the fuel level sensor.
Reconnect the fuel level sensor.Expected Result:The resistance is between 0 and 3.5 Ohms when the indicator is on "F". The correct resistance is between 92 and 98 Ohms when the indicator is on "E".Results:
OK - The resistance is between 0 and 3.5 Ohms when the indicator is on "F". The resistance is between 92 and 98 Ohms when the indicator is on "E". The fuel level sender appears to be OK. Proceed to Test Step 4.
Not OK - The resistance is out of the range.Repair: Replace the fuel level sender. Verify that the repair eliminates the problem.STOPTest Step 4. Check the Supply Voltage to the Buffer
Disconnect the connector at the fuel level buffer.
Turn the keyswitch to the ON position.
Measure the voltage across terminal A (+Battery) and terminal B (digital return) at the connector.
Turn the keyswitch to the OFF position.Expected Result:The supply voltage is approximately 24 VDC.Results:
OK - Battery voltage is present at the connector for the fuel level buffer. The buffer is receiving the correct supply voltage. Proceed to Test Step 5.
Not OK - The buffer is not receiving the correct supply voltage. Proceed to Test Step 7.Test Step 5. Check the Isolated Signal Frequency and the Duty Cycle
Install a 7X-6370 Adapter Cable As (3-PIN BREAKOUT) at the connector for the fuel level buffer.
Illustration 4 g01159881
(A) +24 V Supply (B) Digital Return (C) Signal
Remove the signal wire from the harness side of the connector for the fuel level buffer. Leave the breakout in place.
Turn the keyswitch to the ON position.
Measure the frequency and the duty cycle between terminal B (digital return) and terminal C (signal) at the breakout.
Turn the keyswitch to the OFF position.
Reinstall the signal wire in the connector and remove the breakout. Leave the connector disconnected.Expected Result:The frequency is between 5 and 6.5 kHz. The duty cycle is between 24 and 87 percent.Results:
OK -