In case of performing voltage drop test, make sure the battery of the vehicle is in good health state and charged. Start with disconnecting the primary with the coil pack and ensure that the car cannot be started for some tests. Place one probe of the voltmeter to the battery positive terminal, then connect the second probe to the B+ terminal of the starter; switch the ignition key to the START position and read the voltage. If the voltage is 0.5 volts and above, this indicates that there is high resistance that is in the starter cables or the cable ground hence, it needs repair. If the reading is acceptable, connect the voltmeter between the positive terminal of the battery and the starter M circuit, do the step again, and if the voltage will be 0.5 volts or more then the starter must be reconditioned or replaced. Most automotive parts stores have starter bench testers for use by the customer and is the only sure method of determining the condition of the starter. For the 4.6L engine starter's removal and installation you have to follow these steps: first, disconnect both battery cables; second, take off the intake manifold; third, move the spark plug wires to the side; fourth, detach electrical connectors; fifth, remove vacuum hoses; sixth, deal with the fuel system pressure; and last, take off the starter motor. During the assembly make sure the solenoid terminal nuts are tight, and tighten the battery terminal and the motor terminal up to the recommended torque settings, and the correct procedure for reassembling the intake manifold as well as the other components is followed. In the case of both 4.5L and 4.9L engines, the procedure is to have the system grounded by removing the negative cable before lifting the vehicle and then uninstalling the starter motor cover, the exhaust, and the flexplate inspection cover; follow this by removing the solenoid and battery cable nuts to take off the starter motor. Starter motor installation includes locking the motor onto the starter and joining all leads; afterwards lowering the car and joining the negative terminal.