Massey Ferguson E9173 – Engine ECU: Starter relay control

Indicates an electrical fault in the circuit that controls the starter relay (upper side). E9173 6 indicates a short circuit to earth/ground, and E9173 3 indicates a short circuit to BAT+/battery positive.

• 4700 series
• 5400 series
• 6400 series
• 7400 series
• 7700 series
• 8600 series

1. 1

   Check battery condition and cranking voltage (a fully charged 12V battery should maintain at least 9.6V under load).

2. 2

   Perform voltage-drop tests to find high resistance in cables and earth (ground) straps.

3. 3

   Locate the starter relay in the fuse box and test by swapping it with an identical relay from a non-critical circuit, or use a jumper wire to jump the two pins going to the starter solenoid.

4. 4

   Inspect the wiring harness between the Engine ECU and the starter relay base for chafed wires, melted insulation, or corrosion at the connectors.

5. 5

   Confirm voltage at the relay output and the solenoid trigger.

6. 6

   Measure the solenoid stud-to-stud voltage drop during cranking to ensure the contacts aren't burnt.

1. 1

   Disconnect Power

   Always disconnect the battery's negative terminal before working on the tractor's electrical system to prevent accidental shorts or engine cranking.

2. 2

   Clean Connections

   Clean all battery terminals, starter connections, and ground straps with a wire brush to ensure tight, corrosion-free contacts.

3. 3

   Address Harness Shorts

   If a short was found during the diagnostic phase between the ECU and the relay, repair the damaged wire using proper automotive-grade splicing and heat shrink.

4. 4

   Replace the Relay

   If the wiring is intact but the relay failed the jumper/multimeter test, pull the faulty starter relay from the fuse/relay block and install a new OEM replacement.

5. 5

   Reassemble and Clear Codes

   Reconnect the negative battery terminal. Turn the ignition key to verify the tractor cranks successfully. Clear the inactive fault codes from the dash/ECU using a diagnostic scan tool.