Case IH 3403 (DTC 8A22) - ECU – Electronic Control Unit (ECU): Starter relay low side ECU driver circuit over temperature failure

The ECU actively monitors the starter control relay's low-side control circuit for over-temperature or over-current conditions. If the ECU detects that the circuit is drawing too much current and overheating (or detects a short to the battery on the high side), it logs this fault to protect the internal ECU driver from burning out.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Puma Series Tractors

1. 1

   Check if an external power supply (like a jump starter) was connected improperly or supplied excessive voltage

2. 2

   Test for a faulty charging system or alternator overcharging the circuit

3. 3

   Inspect the starter solenoid for failure or excessive current draw

4. 4

   Inspect the wiring harness between the ECU, starter relay, and starter solenoid for chafed wires causing a short to ground or a short to the battery

5. 5

   Test the starter relay (K-005 / K-062) for internal shorts

6. 6

   If all external wiring and components test good, check the Central Control Unit (CCU) for internal faults

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the battery to prevent accidental shorts or further damage to the ECU.

2. 2

   Locate the Relay

   Access the main fuse and relay panel. Locate the starter relay (designated as K-005 or K-062 depending on the model).

3. 3

   Inspect and Replace Relay

   Pull the relay and inspect the spade terminals and the socket for signs of melting, burning, or corrosion. If damaged or if it fails a bench continuity test, replace the relay.

4. 4

   Trace the Harness

   Using a multimeter, check the continuity of the wiring harness from the relay socket back to the ECU (A-095) and down to the starter solenoid. Repair any damaged, pinched, or exposed wires.

5. 5

   Check the Solenoid

   Test the starter solenoid's resistance. If it is internally shorted and drawing too much amperage, replace the starter solenoid.

6. 6

   Reassemble and Clear Codes

   Reconnect the battery. Use the dealer service tool or the in-cab diagnostic screen to clear the fault codes (some related inducement codes require a specific "Engine Restart Counter Reset" via the dealer tool). Test the starting circuit.