Case IH 339 – Engine Control Module (ECM): Idle Shutdown Vehicle Accessory Relay Voltage is too low

The Engine Control Module (ECM) monitors the voltage level on the idle shutdown relay circuit. This code is triggered when the ECM detects that the pulse width modulated (PWM) signal to the idle shutdown relay is not at system voltage when commanded ON, indicating a low voltage condition or a short circuit to ground. When active, the accessories controlled by the idle shutdown relay are disabled, and the amber Check Engine lamp will illuminate.

• MX Magnum
• STX Steiger
• Magnum
• Steiger
• Puma
• T8000 series
• CVX
• MXM models

1. 1

   Inspect the Idle Shutdown Vehicle Accessory Relay and its socket for pushed-out pins, corrosion, or signs of melting

2. 2

   Test the relay circuit for a short circuit to ground in the relay itself, the OEM harness, or the connectors

3. 3

   Use a multimeter to monitor the voltage level on the relay driver circuit from the ECM to ensure it is receiving the proper command voltage when the key is ON

1. 1

   Disconnect Power

   Turn off the key switch and disconnect the battery to prevent electrical spikes.

2. 2

   Test/Replace the Relay

   Remove the Idle Shutdown Vehicle Accessory Relay. Test it for internal shorts using a multimeter. If it fails or shows high resistance, replace the relay.

3. 3

   Repair the Harness

   If the relay tests good, trace the wiring harness from the relay block back to the ECM. Look for areas where the wire may have chafed against the chassis or engine block, causing a short to ground. Repair any damaged wiring or replace the affected harness section.

4. 4

   Reassemble and Validate

   Reconnect the relay and battery power.

5. 5

   Clear the Code

   To validate the repair, perform a key cycle, start the engine, and let it idle for at least 1 minute. The fault code status should change to INACTIVE. Use an electronic service tool to issue a "Reset All Faults" command and clear the code from the ECM.