This diagnostic code is associated with the 5 VDC power supply on connector 2 of the IQAN Lx A0 module. The "VREF-A Error" code means that some factor is overwhelming the ability of the module to regulate the source voltage between 4.9 VDC and 5.1 VDC.
The possible causes of the diagnostic code are listed:
- A short or open may have occurred on the circuit for the engine speed potentiometer.
- A short or open may have occurred on the circuit for the two-speed travel switch.
Note: Refer to the complete machine schematic for the connections of these inputs with the IQAN Lx A0 module.
Test Step 1. CHECK FOR AN OPEN CIRCUIT.
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the machine harness connectors from the IQAN Lx A0 module.
- At the machine harness connector for the module, check the continuity to ground of the switch contacts with the switch that is activated and with the switch that is not activated. Refer to the complete machine schematic.
Expected Result:
The continuity check is NOT correct.
Results:
- YES - The continuity check is NOT correct. The harness or the switch is faulty. Proceed to Test Step 2.
- NO - The continuity check is correct. Proceed to Test Step 3.
Test Step 2. CHECK THE SWITCH.
- Disconnect the machine harness from the switch.
- Check the continuity to ground of the switch contacts with the switch that is activated and with the switch that is not activated.
Expected Result:
The continuity check is NOT correct.
Results:
- YES - The continuity check is NOT correct. The switch is malfunctioning.
Repair: Repair the switch or replace the switch.
STOP
- NO - The continuity check is correct.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK FOR A SHORT TO +BATTERY
- At the machine harness connector for the module, check the continuity from each of the wires for the switch contact to the contact IQAN Lx A0-8 (wire 909-BU).
Expected Result:
Continuity exists between the source of the battery voltage and the switch circuit.
Results:
- YES - Continuity exists between the source of battery voltage. The machine harness is faulty.
Repair: Repair the machine harness or replace the machine harness.
STOP
- NO - Continuity does not exist between the source of battery voltage and the switch circuit. The machine harness is correct. It is unlikely that the module is faulty. Exit this procedure and perform this procedure again.
Repair: If the cause of the diagnostic code is not found, replace the module.
STOP