Yale 522596-12 – Engine Control Module (ECM) / Engine Control Unit (ECU): Internal Circuity Fault Detection / Electronic Pressure Regulator (EPR) Internal Circuit Problem

Indicates a hardware or internal circuit failure within the Direct Electronic Pressure Regulator (DEPR). The DEPR is a "smart" actuator in the LPG fuel system that receives supply pressure from a mechanical Dual Stage Regulator (DSR) and uses commands to quickly and precisely modulate fuel pressure delivered to the gaseous fuel mixer.

• Yale and Hyster Forklifts
• Yale VX Series (e.g., Veracitor GLP/GDP/GC models)
• Hyster FT Series
• Models equipped with GM, Mazda (2.2L), and Toyota (4Y) LPG engines

1. 1

   Inspect the multi-pin DEPR electrical connector and the wiring harness leading back to the ECU for damaged wires, corrosion, or loose pins.

2. 2

   Perform continuity and voltage checks at the DEPR connector to ensure the ECU is sending the proper signals and that there are no open loops or short circuits in the harness.

3. 3

   If the wiring harness and connector are verified to be in good working order, conclude that the DEPR has failed internally.

1. 1

   Safety First

   Turn off the forklift, disconnect the battery to prevent electrical shock, and close the valve on the LPG tank.

2. 2

   Relieve Pressure

   Safely bleed or relieve the fuel line pressure before opening the system.

3. 3

   Locate the DEPR

   Find the Electronic Pressure Regulator in the engine bay. On newer EControls systems, it is a separate component with a multi-pin connector located after the primary mechanical regulator and before the mixer.

4. 4

   Disconnect Electricals

   Unplug the multi-pin electrical connector from the DEPR.

5. 5

   Remove the DEPR

   Disconnect the LPG fuel hoses routed to the DEPR and unbolt the unit from its mounting bracket.

6. 6

   Install the New Part

   Mount the replacement DEPR, reconnect the fuel lines securely, and plug in the electrical connector.

7. 7

   Test for Leaks

   Slowly open the LPG tank valve and use a soapy water solution on the fittings to ensure there are no gas leaks.

8. 8

   Clear Codes

   Reconnect the battery, start the engine, and use the diagnostic software/dash display to clear the fault codes and verify the repair.