Case IH F-1321-05 - ECU – Engine Control Unit (ECU A-095): Starter relay low side driver circuit open failure

The ECU continuously monitors the K-062 control circuit. If the ECU detects an open circuit condition (infinite resistance/no continuity) on the low side control circuit of the K-062 relay, it will log this fault.

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1. 1

   Verify that the tractor battery power supply has not been connected to an external power supply (like a jump box). Disconnect if present and retest.

2. 2

   Inspect the wiring harnesses and connectors between the ECU (A-095) and the starter control relay (K-062) for physical damage, bent or dislocated pins, corroded terminals, or broken wires.

3. 3

   Verify that all connectors are fully seated. Flex the involved harnesses while monitoring the display to reveal any intermittent breaks or shorts in the wiring.

4. 4

   Use a multimeter to check for continuity on the low side control circuit between the ECU and the K-062 relay. An open circuit indicates a broken wire or a failed relay coil.

5. 5

   Check the ECU A-095 for the appropriate software version, as a re-flash may be necessary if wiring and relay test normal.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to ensure safety while working on the electrical system.

2. 2

   Locate Components

   Locate the ECU and the relay panel containing the K-062 (Starter Control Relay) and K-005 (Main Starter Relay).

3. 3

   Test the Relay

   Remove the K-062 relay and test the resistance across its coil pins. If the coil is open (infinite resistance), the relay has failed and must be replaced.

4. 4

   Repair Wiring

   If the relay is good, trace the low side driver wire from the relay block back to the ECU harness. Locate the break in the wire or the corroded pin causing the open circuit. Repair the damaged conductor or replace the affected connector terminal.

5. 5

   Reassemble and Clear

   Reinstall the relay, reconnect the battery, and turn the key on. Operate the machine while monitoring the diagnostic display.

6. 6

   Final Verification

   If the display indicates normal readings, erase the fault code and verify that the machine starts and operates without triggering the code again.