Yale 522604-4 – VSM (Vehicle System Manager): Fuel Relay PWM Control OORL

Triggers when the controller detects that the Pulse Width Modulation (PWM) signal circuit controlling the fuel relay has dropped below the acceptable voltage range.

• Yale and Hyster Forklifts
• Yale and Hyster forklifts (2005 and newer)
• Yale Veracitor VX series
• GC135VX
• GP040-060MX
• ERP20VT

1. 1

   Remove the fuel relay and test the resistance across the relay coil pins with a multimeter to check for an internal open circuit.

2. 2

   Probe the wiring harness connecting the PDM/VSM to the fuel relay socket to check for continuity to ground (short-to-ground test).

3. 3

   Check for continuity from the controller's output pin to the relay socket to ensure the wire is not broken (open circuit test).

4. 4

   Inspect the PDM and relay sockets for pushed-back pins, corrosion, or spread terminals that could cause an open circuit.

1. 1

   Locate the Fuel Relay

   Access the Power Distribution Module (PDM) / main fuse box, usually located under the hood or dash panel depending on the chassis. Identify the Fuel Relay.

2. 2

   Swap/Test the Relay

   Swap the fuel relay with a known good relay of the same type (e.g., the horn or work light relay). Clear the codes and cycle the key. If the code changes to a different circuit or goes away, the relay is faulty and must be replaced.

3. 3

   Repair the Wiring Harness

   If the relay is good, trace the wire from the PDM relay driver to the VSM. If your multimeter showed a short to ground or an open circuit during diagnostics, locate the chafed wire or broken connection and repair/solder it.

4. 4

   Controller Replacement

   If the relay is perfectly fine and the wiring harness tests show no shorts or opens, the VSM or PDM has an internal driver failure and will need to be replaced and re-flashed/calibrated by a Yale dealer.