Case IH 17908 (F-3511-04) - ECU – ECM (Engine Control Module): ECM 5 volt sensor supply 3 high side output driver shorted to ground failure only.

The ECM provides a regulated 5-volt reference signal (Supply #3) to power a specific group of engine sensors. The ECM has detected that the voltage on this specific circuit has dropped to 0 volts because the high side output driver is shorted directly to ground. This condition will disable all sensors sharing the #3 5-volt supply circuit.

• VESTRUM CVX
• Farmall series
• Maxxum series
• Puma series
• Optum series
• Steiger series
• Axial-Flow combines

1. 1

   Inspect the engine wiring harness for chafing, rubbing, or pinched wires that could cause the 5V supply #3 circuit to short against the engine block or chassis ground.

2. 2

   Disconnect the sensors that share the 5V sensor supply #3 circuit one at a time. Monitor the fault codes. If the 17908 'shorted to ground' code goes inactive or changes to an 'open circuit/under voltage' code (such as 17909) when a specific sensor is unplugged, that sensor has an internal short and is the root cause.

3. 3

   Inspect the ECM connectors (specifically the 60-pin engine connector and 94-pin vehicle connector) for bent pins, pushed-out terminals, moisture, or corrosion.

4. 4

   With the battery disconnected and the ECM unplugged, use a multimeter to measure the resistance to ground on the 5V supply #3 pin at the ECM harness connector to confirm if the short exists in the wiring.

1. 1

   Turn off the key switch and disconnect the battery

   This prevents electrical spikes.

2. 2

   Perform the sensor isolation test

   If a sensor is found to be internally shorted, remove and replace the faulty sensor.

3. 3

   Repair or replace the wiring harness

   If the short is traced to the wiring harness, locate the damaged section. Repair the wire using approved splicing and heat-shrink methods, or replace the affected harness section if the damage is extensive.

4. 4

   Replace the ECM

   If the wiring harness tests perfectly (infinite resistance to ground) and all sensors are unplugged, but the ECM still actively logs the internal driver short, the ECM's internal driver has failed. The ECM must be replaced and programmed by a dealer.

5. 5

   Reconnect all sensors and ECM connectors

6. 6

   Clear the fault codes

   Reconnect the battery, turn the key on, and use a diagnostic service tool to clear the fault codes.

7. 7

   Verify the repair

   Start the engine and verify that the fault code does not return and that sensor data is reading correctly.