Starter Motor - Ground Circuit Test

A slow cranking condition can be caused by resistance in the ground or return portion of the cranking circuit. This procedure checks the voltage drop in the ground circuit.

1. Connect a remote starter switch between starter solenoid "S" terminal and the battery positive terminal.
2. Connect the multimeter positive lead to the starter motor housing (the connection must be clean and free of rust or grease). Connect the negative lead to the negative battery terminal.
3. Place gear selector lever in Park or Neutral.
4. Engage the remote starter switch and crank the engine. Read and record the voltage reading. The reading should be 0.5 volt or less.

   Courtesy of FORD MOTOR COMPANY

5. If the voltage reading is greater than 0.5 volt, clean the negative cable connections at the battery, the body ground connections and the starter ground connection. Retest.
6. If the voltage reading is greater than 0.5 volt, install a new negative battery cable. REFER to: Battery Cables - 2.7L EcoBoost (238kW/324PS) .
7. If the voltage reading is less than 0.5 volt and the engine still cranks slowly, install a new starter motor. REFER to: Starter Motor 2.7L EcoBoost  .