Case IH 522831-04 - PCM – PCM: Short circuit to ground or undervoltage on HSD (High Side Drive) output-2

The control module is detecting that the voltage on the circuit for Output 2 is dropping below the expected operating threshold, which is typically caused by the power wire shorting directly to the chassis ground, a failed component drawing too much current, or a general system undervoltage condition.

• MAGNUM AFS Connect
• Steiger AFS Connect
• Optum AFS Connect
• Puma AFS Connect
• Axial-Flow 260 series
• 7260 Tier 4B
• Patriot 50 Series
• Older legacy machines equipped with the aftermarket Case IH Pro 1200 Guidance Kit

1. 1

   Verify that the tractor's main battery and charging system are supplying a healthy 12V to the PCM, as a general low-voltage condition can trigger an FMI 04 undervoltage code.

2. 2

   Visually inspect the wiring harness exiting the PCM for rub-throughs, pinched wires, or melted insulation that could cause the Output-2 wire to touch the chassis ground.

3. 3

   Disconnect the PCM and the end-component. Inspect the pins for corrosion, moisture ingress, or damage.

4. 4

   Perform an isolation test: Disconnect the component powered by HSD Output-2 and turn the key on. If the fault code changes from a short-to-ground (04) to an open-circuit code, the short is internal to the component. If the 04 code remains, the short is in the wiring harness.

1. 1

   Power Down

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

2. 2

   Locate the PCM

   Locate the Processing & Connectivity Module (typically mounted in the cab roof or behind the interior trim, depending on the cab layout).

3. 3

   Test the Circuit

   Using a digital multimeter set to ohms/continuity, probe the HSD Output-2 pin on the harness connector and the chassis ground.

4. 4

   Trace and Repair

   If continuity to ground is present (and it shouldn't be), trace the harness along the machine frame to find the short. Repair the damaged wire using OEM-approved heat-shrink butt connectors and re-loom the harness.

5. 5

   Component Replacement

   If the wiring tests good but the component itself is internally shorted to ground, replace the auxiliary component.

6. 6

   PCM Verification

   If the wiring is completely intact and the component is healthy, but the PCM continues to output an undervoltage/short code, the internal High Side Driver inside the PCM has failed. The PCM must be replaced.

7. 7

   Reassembly

   Reconnect all harnesses, restore battery power, and clear the inactive fault codes via the Pro 1200 / Pro 700 display. Test operate the machine to ensure the code does not return.