Case IH 596 – Engine Control Module (ENG / ECM): Battery voltage is too high

This condition is triggered when the control module detects that the electrical charging system or supply voltage has exceeded the normal operating limit, typically measuring greater than 16.2 volts.

• MX Magnum
• STX Steiger
• Case IH and New Holland (CNH) agricultural and construction equipment
• Tractors
• Combines
• Loaders

1. 1

   Verify that no external battery charger or 24V jump-start system is currently connected to the machine.

2. 2

   With the engine running, test the alternator output voltage at the battery terminals (spiking above 16.2 volts indicates overcharging).

3. 3

   Stop the engine, remove the connector from the Engine ECM, and inspect the contacts for shorts or corrosion.

4. 4

   Check the alternator voltage regulator, as a malfunction here is the most common cause of this failure mode.

1. 1

   Disconnect Power

   Turn off the engine and disconnect the negative battery cable to ensure safety.

2. 2

   Replace the Charging Component

   If the diagnostic tests confirm the alternator is overcharging, remove the drive belt and unbolt the alternator. Depending on the specific alternator model, you will need to replace either the internal/external voltage regulator or the entire alternator assembly.

3. 3

   Inspect the Battery

   Prolonged exposure to high voltage can boil the battery electrolyte and cause internal damage. Inspect the battery case for bulging or leaks, and perform a load test. Replace the battery if it has been compromised.

4. 4

   Reassemble and Clear Codes

   Install the new alternator/regulator, reattach the drive belt, and reconnect the battery cables. Start the engine and verify that the charging voltage is now within the normal range (typically 13.5V to 14.5V). Clear the active ENG 596 fault code from the ECM.