09491-34008 Suzuki MAIN JET #170

Table 1
Diagnostic Codes Table    
Description     Conditions which Generate this Code     System Response    
544-2 Engine Cooling Fan Speed Sensor erratic, intermittent, or incorrect     The signal for engine fan speed is unavailable or abnormal.     The warning lamp will illuminate, if equipped.
The code is active.
The code is logged.
The engine may experience overcooling.    
544-8 Engine Cooling Fan Speed Sensor abnormal frequency, pulse width, or period     The signal for engine fan speed is unavailable or abnormal.     The warning lamp will illuminate, if equipped.
The code is active.
The code is logged.
The engine may experience overcooling.    
544-12 Engine Cooling Fan Speed Sensor failure     The signal for engine fan speed is unavailable or abnormal.     The warning lamp will illuminate, if equipped.
The code is active.
The code is logged.
The engine may experience overcooling.
The Electronic Control Module (ECM) may default to maximum fan speed.    The engine cooling fan speed sensor provides a signal to the ECM. The ECM controls fan speed by varying the inversely proportional current to the fan control solenoid.The engine cooling fan speed sensor receives a supply voltage of 10.0 0.5 VDC from the ECM. The sensor outputs a current that is directly proportional to fan speed. The output current varies between 7 mA to 14 mA over the speed range between 200 rpm and 1800 rpm. The varying sensor output current goes through the speed resistor assembly. The current is converted to a Pulse Width Modulated (PWM) voltage. This voltage crosses the +5 V that is generated by a voltage divider within the "speed resistor assembly" and a cycle is triggered.
Illustration 1 g01314659
Schematic for the fan speed sensor
Illustration 2 g01341884
P1 ECM connector (P1-12) Sensor Return (P1-13) Engine fan speed signal (P1-35) Switch returnTest Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the ECM connector J1/P1. Inspect all of the other connectors for the circuit. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
Check the harness and the wiring for abrasion and for pinch points.
If applicable, use Caterpillar Electronic Technician (ET) to perform the "Wiggle Test" on the wires that are associated with the cooling fan.Expected Result:All connectors, pins, and sockets are correctly installed and the harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are correctly coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Engine Fan Speed with Cat ET
Remove the electrical power from the ECM.
Connect Cat ET to the service tool connector.
Restore the electrical power to the ECM.
Access the "Status Screen" in Cat ET and verify that there is a speed signal displayed.
If a speed signal is displayed, perform the following procedure (if applicable).
In Cat ET, access the "Override Screen" under the "Diagnostics" menu.
Verify that the engine speed is above 400 RPM.
Set the fan speed to 600 rpm in the "Override Screen".Note: If there is no signal for fan speed, the ECM will be running the cooling fan in "Open Loop" mode. In "Open Loop" mode, if 0 rpm is typed into the Override Screen, the ECM will set minimum fan speed. If a figure above 0 rpm is entered, the ECM will set a maximum fan speed. If the fan is in "Open Loop" mode, check the fan speed circuit for faults. If necessary, change the fan speed sensor.Note: Also verify the accuracy of the fan speed at 1200 rpm and 1800 rpm.
Use a 351-8635 Tachometer Kit to determine the actual speed of the fan.
Compare the engine fan speed that is reported by Cat ET to the actual engine fan speed that is reported by the photo-tachometer.
Disable all overrides, and exit the Override Screen.Expected Result:There is a fan speed signal displayed and (if applicable) the actual fan speed is within 50 rpm of the engine fan speed that is reported by Cat ET.Results:
OK - There is a fan speed signal displayed and (if applicable) the actual fan speed is within 50 rpm of the engine fan speed that is reported by Cat ET.Repair: The sensor is operating correctly. There may be an intermittent electrical problem in a connector or in the harness. If an intermittent problem is suspected, refer to service Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - There is not a signal for the fan speed. The engine fan speed is not within the desired rpm range (if applicable). Proceed to Test Step 3.Test Step 3. Check the +10 V Supply Voltage for the Speed Sensor and the Speed Resistor Assembly
Remove the electrical power from the ECM.
Disconnect the connector for the engine cooling fan speed sensor.
Restore the electrical power to the ECM.
Measure the sensor supply voltage for the engine cooling fan speed sensor between terminal 2 (+10V supply) and engine ground.
Measure the supply voltage for the speed resistor assembly between terminal 1 (+10V supply) and the engine ground.Expected Result:The voltage is between 9.5 VDC and 10.5 VDCResults:
OK - The voltage is acceptable. The correct voltage is reaching the sensor connector and the speed resistor assembly. Proceed to Test Step 4.
Not OK - The voltage is not acceptable.Repair: The +10V supply voltage is not reaching the sensor or the resistor assembly. There is a problem with the machine wiring or there is a problem with the +10V supply voltage. Refer to the troubleshooting manual for the machine application.STOPTest Step 4. Check the Speed Resistor Assembly Return
Remove the electrical power from the ECM.
Disconnect the speed resistor assembly return wire from terminal 3