Case IH 3438 (DTC 7A61) - ECU – Engine Control Unit (ECU): Auxiliary power relay high side driver circuit short to ground failure

The Engine Control Unit (ECU) has detected a short to ground condition in the control circuit (high side) of the auxiliary power relay (designated as K-064). The ECU controls the voltage to this relay and continuously monitors the circuit; if the voltage drops unexpectedly due to a short to ground, this fault is logged.

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

1. 1

   Connect the Electronic Service Tool (EST) to verify if the fault code is currently active or intermittent

2. 2

   Inspect and test the K-064 auxiliary power relay coil for internal faults or a dead short

3. 3

   Check the K-064 high side control circuit wiring harness between the relay receptacle and the ECU for a short to ground condition

4. 4

   Verify the ECU A-095 for a software glitch or hardware failure if the relay and wiring test good

1. 1

   Locate the Relay

   Locate the auxiliary power relay (K-064) in the machine's main distribution panel (MDP).

2. 2

   Test/Replace the Relay

   Remove the relay and test it. If the coil is faulty, replace the K-064 relay with a new OEM unit.

3. 3

   Trace the Harness

   If the relay is functional, use a multimeter to check for continuity to ground on the non-powered side of the relay receptacle. Trace the wiring harness back to the ECU A-095. Repair any chafed, pinched, or exposed wires causing the short to ground.

4. 4

   Software Flash

   If the wiring harness and relay are both in good working order, connect the EST and attempt to reinstall or update the ECU A-095 software.

5. 5

   Replace the ECU

   If the ECU software cannot be reinstalled or the fault immediately returns after a flash, the ECU A-095 has suffered an internal driver failure and must be replaced.