Case IH 17658 (F-518404-04) - ECU – Engine Control Module (ECM / ECU): ECM 12/24 volt actuator supply 6 is shorted to ground

The Engine Control Module provides power to various engine actuators through multiple dedicated supply circuits. This code triggers when the ECU detects that the voltage on "Supply 6" is being routed directly to the chassis ground (or negative battery terminal) without passing through the intended load.

• VESTRUM CVX
• Farmall
• Maxxum
• Puma
• Optum
• Austoft 9900

1. 1

   Verify Active Code: Ensure the ignition is ON and use a diagnostic tool (such as CNH EST or TEXA IDC5) to confirm if code 17658 is currently active or stored.

2. 2

   Harness Inspection: Disconnect the battery. Disconnect the engine harness from the Bosch MD1CE101 ECU. Locate pins 5.13 and 6.42 on the harness connector.

3. 3

   Check for Ground Short: Using a multimeter, measure the resistance between pins 5.13 / 6.42 on the harness side and a known good chassis ground. If there is continuity (low resistance), a short to ground is present in the wiring or a connected component.

4. 4

   Isolate the Component: Trace the wiring from pins 5.13 and 6.42 to their respective engine actuators. Disconnect the actuators on this circuit one by one. If the short to ground disappears on your multimeter when a specific actuator is unplugged, that actuator is internally shorted.

5. 5

   Visual Inspection: Carefully inspect the wiring harness routing for chafed, melted, or rubbed insulation where the wire might be touching the engine block or metal brackets.

1. 1

   Power down machine

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Expose the wiring

   If the diagnostic checks point to a harness issue, carefully open the wire loom tracing back from the affected actuator to ECU pins 5.13 and 6.42.

3. 3

   Repair the harness

   Locate the section of the wire where the insulation has rubbed through and is contacting bare metal. Cut out the damaged section, solder in a new piece of wire of the same gauge, and seal it with marine-grade heat shrink tubing. Re-loom and secure the harness away from vibration points.

4. 4

   Replace faulty actuator

   If the wiring is intact but an actuator tested as internally shorted in the diagnostic phase, remove and replace the faulty actuator.

5. 5

   Reassemble and clear codes

   Reconnect all ECU and actuator plugs. Reconnect the battery. Turn the key ON, connect the diagnostic tool, and clear the fault codes.

6. 6

   Test run

   Start the engine and operate the machine to verify that fault code 17658 does not return.