Tools Required

Perform the following actions in order to prevent the engine from starting when performing the following tests:

The starter motor cannot be measured against specifications while on the vehicle. Perform a test inspecting for excessive resistance in the starting circuit.

Allow the vehicle to remain at room temperature before performing the following tests. Colder weather causes higher resistance in the circuit.

On diesel engine vehicles, disable the following components prior to performing the circuit test:

The following test will not be valid if the preheater systems are not disabled:

Notice: Do not operate the starter motor continuously for more than 30 seconds without pausing to allow it to cool at least 2 minutes. Overheating from excessive cranking will seriously damage the starting motor.

1. Disable the following components, as equipped, on diesel engine vehicles:

•	The air intake heater system.

•	Refer to Air Intake Heater in Engine Controls.

•	The glow plug system

•	Refer to Glow Plug System in Engine Controls.

2. Verify that the battery is fully charged.

Perform the following steps if the battery has been recently charged:

•	Remove the surface charge.

•	Perform a load test. Refer to Charging System Check Charging System Check Battery Testing.

3. Connect the J 39200 across the battery in order to read the open circuit voltage.

The open circuit voltage should measure at least 12 volts.

4. Perform the following steps in order to inspect for excessive resistance in the cranking circuit:

4.1.	Connect the J 39200 J 39200 across the negative battery post and the positive terminal of the starter solenoid.

4.2.	Crank the engine.

4.3.	Observe the voltage reading on the J 39200 J 39200 .

Excessive resistance exists in the cranking circuit if the J 39200 J 39200 reads 2 volts or more when cranking.

4.4.	Inspect the cranking circuit for the following conditions:

•	Loose connections

•	Corroded connections

•	Dirty connections

4.5.	Connect the J 39200 J 39200 across the battery in order to measure the voltage reading in areas where the J 39200 J 39200 will not reach from the battery to the starter.

5. Perform the following steps in order to inspect for excessive resistance in the starter ground circuit:




5.1.	Connect one end of the J 39200 J 39200 to the negative battery cable.





5.2.	Connect the other end of the J 39200 J 39200 to the ground stud on the engine block near the starter motor.

5.3.	Crank the engine.

5.4.	Observe the voltage reading on the J 39200 J 39200 .

The J 39200 J 39200 should read about 0.2 volt or less when cranking. If the reading is 0.5 volt or higher, excessive resistance exists in the starter ground circuit.

6. Perform the following steps in order to inspect the resistance of the power supply (B+).

6.1.	Connect the J 39200 J 39200 to the positive terminal of the battery and to the positive terminal of the starter solenoid.

6.2.	Crank the engine.

6.3.	Observe the voltage reading on the J 39200 J 39200 .

Excessive resistance in the starter power supply (B+) exists if the J 39200 J 39200 reads 0.9 volt or higher when cranking.

Remove the starter motor for repair if the following conditions exist:

Service the PG-260 starter motor as an assembly replacement.

Tools Required

J 39200 Digital Multimeter

The 37-MT/350 starter motor that operates on the diesel engine is equipped with thermostat for overcrank protection. If the starter will not crank, use the following procedure in order to inspect for an open thermostat:

1. Ensure that the motor is cool when the circuit should be closed.

The thermostat opens when the thermostat senses starter temperatures exceeding 140°C (285°F).

2. Disconnect the wiring from the thermostat connector.
3. Connect the J 39200 to the two terminals on the thermostat.
4. Observe the resistance reading on the J 39200 .

The resistance should measure zero ohms.

5. If the J 39200 does not read zero ohms, replace the thermostat.