Starter Motor - Motor Feed Circuit

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Always disconnect the battery ground cable at the battery before disconnecting the starter motor battery terminal lead. If a tool is shorted at the starter motor battery terminal, the tool can quickly heat enough to cause a skin burn. Failure to follow this instruction may result in serious personal injury.

NOTE: Always connect the 73III Automotive Meter at the component terminal rather than at the wiring end connector. Making a connection at the wiring end connector could result in false readings because the meter will not pick up a high resistance between the wiring connector and the component.

WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in FIRE SUPPRESSION SYSTEM article. Failure to follow the instructions may result in serious personal injury.

Make sure the battery is fully charged. Refer to BATTERY, MOUNTING & CABLES article.
Disconnect the Inertia Fuel Shutoff (IFS) switch.
Connect a remote starter switch between the starter motor solenoid S-terminal and the battery positive (+) terminal.

Connect the 73III Automotive Meter positive lead to the battery positive (+) post. Connect the negative lead to the starter motor solenoid M-terminal.

Fig 1: Motor Feed Circuit

Courtesy of FORD MOTOR CO.

Item	Part Number	Description
1	-	S-terminal
2	-	Remote starter switch
3	10653	Battery
4	-	73III Automotive Meter
5	-	B-terminal
6	-	M-terminal

Engage the remote starter switch. Read and record the voltage. The voltage reading should be 0.5 volt or less.
If the voltage reading is 0.5 volt or less, go to the Starter Motor - Motor Ground Circuit component test below.
If the voltage reading is greater than 0.5 volt, indicating excessive resistance, move the 73III Automotive Meter negative lead to starter motor solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volt, the concern is either in the connections at the starter motor solenoid or in the starter motor solenoid contacts.
Remove the cables from the starter motor solenoid B-, S- and M-terminals. Clean the cables and connections and reinstall the cables to the correct terminals. Repeat Steps 3 through 6. If the voltage drop reading is still greater than 0.5 volt when checked at the M-terminal or less than 0.5 volt when checked at the B-terminal, the concern is in the solenoid contacts. Install a new starter motor.
If the voltage reading taken at starter motor solenoid B-terminal is still greater than 0.5 volt after cleaning the cables and connections at the solenoid, the concern is either in the positive (+) battery cable connection or in the positive battery cable itself.

WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to FIRE SUPPRESSION SYSTEM article. Failure to follow these instructions may result in serious personal injury.

By moving the 73III Automotive Meter negative lead toward the battery and checking each mechanical connection point, the excessive voltage drop can be located. When the high reading disappears, the last mechanical point that was checked is the concern. Repair or install a new connection as required.