The neutral safety switch is wired into the circuit going to the starter solenoid. When the transmission is in forward or reverse gear, the switch is in the OPEN position (disconnected). This action prevents current from activating the solenoid and starter when the ignition switch is turned to the START position. When the transmission is in neutral or park, the switch is closed (connected), allowing current to flow to the starter when the ignition is turned.

A misadjusted or bad neutral safety switch can keep the engine from cranking. If the vehicle does not start, you should check the action of the neutral safety switch by moving the shift lever into various positions while trying to start the vehicle. If the starter begins to work, the switch needs to be readjusted.

To readjust a neutral safety switch, loosen the fasteners that hold the switch. With the switch loosened, place the shift lever into park (P). Then, while holding the ignition switch in the START position, slide the neutral switch on its mount until the engine cranks. Without moving the switch, tighten the fasteners. The engine should now start with the shift lever in park or neutral. Check for proper operation after the adjustment.

If by adjusting the switch to normal operation is not resumed, it may be required to test the switch. All that is required to test the switch is a 12-volt test light.

To test the switch, touch the test light to the switch output wire connection while moving the shift lever. The light should glow as the shift lever is slid into park or neutral. The light should not work in any other position. If the light is not working properly, check the mechanism that operates the switch. If the problem is in the switch, replace it.

Starter Current Draw Test

STARTING CIRCUIT MAINTENANCE
The condition of the starting motor should be carefully checked at each PM service. This permits you to take appropriate action, where needed, so equipment failures caused by a faulty starter can be reduced, if not eliminated.

The starter current draw test measures the amount of amperage used by the starting circuit. It quickly tells you about the condition of the starting motor and other circuit components. If the current draw is lower or higher than the manufacturer's specifications, there is a problem in the circuit.

A visual inspection for clean, tight electrical connections and secure mounting at the flywheel housing is the extent of the maintenance check. Then operate the starter and observe the speed of rotation and the steadiness of operation. To prevent the starter from overheating, do NOT operate the starter for more than 30 seconds.

To perform a starter current draw test, you may use either a voltmeter or inductive ammeter or a battery load tester. These meters are connected to the battery to measure battery voltage and current flow out of the battery. For setup procedures, use the manufacturer's manual for the type of meter you intend to use.

If the starter is not operating properly, remove the starter, disassemble it, and check the commutator and brushes. If the commutator is dirty, it may be cleaned with a piece of No. 00 sandpaper. However, if the commutator is rough, pitted, or out-of-round or if the insulation between the commutator bars is high, it must be reconditioned using an armature lathe.

To keep a gasoline engine from starting during testing, disconnect the coil supply wire or ground the coil wire. With a diesel engine, disable the fuel injection system or unhook the fuel shutoff solenoid. Check the manufacturer's service manual for details.

With the engine ready for testing, crank the engine and note the voltage and current readings. Check the manufacturer's service manual. If they are not within specifications, there is something wrong with the starting circuit.

Brushes should be at least half of their original size. If not, replace them. The brushes should have free movement in the brush holders and make good, clean contact with the commutator.

Once the starter is checked and repaired as needed, it should be reassembled, making sure that the starter brushes are seated. Align the housings and install the bolts securely. Install the starter in the opening in the flywheel housing and tighten the attaching bolts to the specified torque. Connect the cable and wire lead firmly to clean terminals.