DTC 523930-4 - Clutch FWD1/Return Circuit OORL
POSSIBLE CAUSE
A. COIL DRIVER/DRIVER RETURN SHORTED TO GROUND
B. FUNCTIONAL VALVE FAILURE
C. FUNCTIONAL FAILURE IN CONTROLLER

CAUSE A - COIL DRIVER/DRIVER RETURN SHORTED TO GROUND
PROCEDURE OR ACTION:
NOTE: The coil drive control signals, where two valves are shown in the schematic, share a common return.
1. Ensure truck power is OFF.
2. Disconnect indicated connectors from the VSM and the control valves.
3. Change DMM to ohms scale. Verify DMM zero reading.
4. Measure the resistance between each indicated pin of the VSM connector (+) and the negative ( ) terminal of
the battery.
Is the resistance less than 0.5 ohms on any of the pins?
YES: The coil driver/driver return output has a short to ground in the harness. Locate and repair/replace shorted
wire/connection. See Wire Harness Repair 2200 SRM 1128.
NO: Go to Cause B.

CAUSE B - FUNCTIONAL VALVE FAILURE
PROCEDURE OR ACTION:
1. At the valve connector(s), measure resistance between the coil pin(s).
Is the resistance less than 0.5 ohms?
YES: The base control valve coil is internally shorted. Replace valve coil. See Main Control Valve 2000 SRM
1137. Depending on your lift truck see, Powershift Transmission, Repair 1300 SRM 1129 or Single Speed
PowerShift, Aluminum Transmission 1300 SRM 1421.
NO: Go to Cause C.

CAUSE C - FUNCTIONAL FAILURE IN CONTROLLER
PROCEDURE OR ACTION:
1. Ensure all previous procedures have been completed.
2. Ensure truck power is OFF.
3. Ensure that all connections to the controller are completely inserted.
4. Ensure truck power is OFF for no less than 30 seconds, and then to ON to clear displayed DTC.
Does reported DTC reoccur?
YES: Go to Step 5.
NO: Problem corrected. Resume operation.
5. At the DSC, press ENTER to access Main Menu.
6. Scroll to VIEW VERSIONS, press ENTER.
7. Scroll to TRUCK SERIAL NUMBER, press ENTER.
8. View the TRUCK SERIAL NUMBER on the display.
Does the truck serial number on display match serial number on truck nameplate (VSM Only)?
YES: Go to Step 9.
NO: Controller has been substituted from another truck. Replace VSM with VSM that has the correct truck serial
number or obtain new VSM with correct Serial number/ CDF. See Electrical System 2200 SRM 1142.
9. Resident Service Approval Required prior to VSM replacement for Trucks under warranty. Make sure
to indicate the DTC code(s) on the warranty claim and include an accurate problem description leading to the
controller replacement.
10. For other controllers, Replace indicated controller. (ECU-ECM/GCU/TCU). See Electrical System 2200 SRM
1142. For GM 4.3L LPG engines, see LPG Fuel System, GM 4.3L Engine With GFI 900 SRM 1242. For GM
4.3L gasoline engines, see Gasoline Fuel System, GM 4.3L Engine With GFI 900 SRM 1244 for all controllers.
11. Reinstall all removed components and ensure that all connectors are completely inserted.
12. Repeat Component Operational Check.
END POSSIBLE CAUSES