Case IH 19361 (F-158-16) - ECU – DCU (Dosing Control Unit): Battery voltage is too high to allow proper diagnosis of output powerstages.

When the supply voltage exceeds the maximum allowable threshold, the control module cannot safely operate or diagnose its internal output power stages (which drive the DEF pump, heaters, and dosing valve). To protect its internal circuitry from burning out, the module shuts down or limits the Selective Catalytic Reduction (SCR) system, which will eventually trigger an engine derate.

• VESTRUM CVX
• Magnum 235-340 (Series 4)
• Steiger 350-600
• Farmall 40-45-50 (with Cab and CVT)
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Axial-Flow 6130
• Axial-Flow 7130

1. 1

   Measure charging system output voltage at the battery terminals with the engine running (~13.5V-14.5V for a 12V system, or ~27V-29V for a 24V system) to ensure the alternator is not overcharging.

2. 2

   Measure the DCU supply voltage at the power supply pins (supplied by the 20A DCU fuse, often F-072) to chassis ground.

3. 3

   Inspect the wiring harness for a short to a higher voltage source, damaged, bent, or dislocated pins, corroded terminals, or broken wires.

4. 4

   Verify the DCU ground connections, as a poor ground can cause floating voltage readings.

5. 5

   Check for internal DCU failure if the alternator is charging normally and the supply voltage at the connector is within spec, but the DCU still reports a high voltage fault via the Electronic Service Tool (EST).

1. 1

   Test and Resolve Alternator Issues

   If diagnostics revealed an overcharging alternator, replace the alternator or voltage regulator. Clear the fault codes and run the machine to verify the fix.

2. 2

   Repair Harness Shorts

   If diagnostics revealed a short to power in the harness, trace the wiring back to the fuse panel and repair the damaged wire.

3. 3

   Software Reload

   If the voltage supply is normal but the code persists, connect the EST and attempt to re-load the appropriate DCU software. Sometimes a software glitch can cause false voltage readings.

4. 4

   Replace the DCU

   If the software reload does not resolve the fault condition, the DCU must be replaced. Turn off the main power supply/battery disconnect switch before disconnecting the DCU connector. Remove the mounting hardware, disconnect the DEF lines, and install the new DCU.

5. 5

   Program the New DCU

   A new DCU requires software installation and configuration via the EST.

6. 6

   Final Testing

   Clear the fault codes, run the engine, and use the EST to perform a Urea Dosing System Test (UDST) to ensure the system builds adequate pressure and no codes return.