System Operation Description:
The possible causes of this failure are listed below:
- The battery is discharged or the battery is faulty.
- The cables to the starter have failed.
- The ignition switch has failed.
- The engine is locked.
- The starting motor solenoid has failed.
- The starting motor has an internal problem.
The following tables will be referenced in troubleshooting the starting motor.
|TYPICAL SYSTEM VOLTAGE DURING CRANKING AT VARIOUS AMBIENT TEMPERATURES|
|Temperature||12 Volt System||24 Volt System|
|-23 °C (-9.4 °F) to
-7 °C (19.4 °F)
|6 to 8 Volts||12 to 16 Volts|
|-7 °C (19.4 °F) to
10 °C (50 °F)
|7 to 9 Volts||14 to 18 Volts|
|10 °C (50 °F) to
27 °C (80 °F)
|8 to 10 Volts||16 to 20 Volts|
|MAXIMUM ACCEPTABLE VOLTAGE DROPS DURING CRANKING|
|Circuit||12 Volt System||24 Volt System|
|Battery positive post to the positive terminal on the starting motor||0.3 Volts||0.5 Volts|
|Battery negative post to the negative terminal on the starting motor||0.7 Volts||1.4 Volts|
|Drop across disconnect switch||0.5 Volts||1.0 Volts|
|Battery positive post to the positive terminal on the solenoid||0.4 Volts||1.0 Volts|
|Battery terminal of the solenoid to the motor terminal of the solenoid||0.4 Volts||0.8 Volts|
Test Step 1. CHECK THE BATTERY VOLTAGE
- Attempt to crank the engine. Measure the battery voltage with the digital multimeter. Measure the voltage at the battery posts. Do not measure the voltage at the terminal of the battery cable.
- Compare the voltage to table 1.
The battery voltage is equal to or greater than the voltage in table 1.
- OK – Battery voltage is correct. Go to test step 2.
- NOT OK – Battery voltage is too low.
Repair: Check the charging system. See Special Instruction, REHS0354, “Charging System Troubleshooting”.
Test Step 2. TEST THE DISCONNECT SWITCH
- Ensure that the disconnect switch is in the CLOSED position.
- Measure the resistance across the terminals of the disconnect switch.
The resistance should be less than 5 ohms.
- OK – The resistance is less than 5 ohms. Proceed to test step 3.
- NOT OK – The resistance is greater than 5 ohms.
Repair: Replace the battery disconnect switch.
Test Step 3. TEST CABLES FROM THE BATTERY TO THE STARTING MOTOR
- Visually inspect the battery cable terminals for the following conditions:
- Loose connections
- Corroded cables
The cables should be clean and the cables should be tight.
- OK – Battery cables are in good condition. Proceed to test step 4.
- NOT OK – Battery cables are not in good condition.
Repair: Clean the terminals or replace the terminals. Tighten the terminals.
Test Step 4. TEST CABLES FROM THE BATTERY TO THE STARTING MOTOR FOR VOLTAGE DROP
- Attempt to crank the engine. Measure the voltage from “Mtr” terminal to ground.
The battery voltage is less than the voltage in table 2.
- OK – The voltage drop is less than the specified voltage drop. Proceed to test step 5.
- NOT OK – The voltage drop is greater than the specified voltage drop.
Repair: Repair the cables or replace the cables. Repeat the voltage measurement. If the voltage remains low, measure the voltage drop across each component that is listed in table 2. Replace all components that are out of specification.
Test Step 5. CHECK ENGINE ROTATION
- Remove the starter from the engine.
- Turn the engine by hand.
The engine turns with normal effort.
- YES – The engine turns with normal effort. Proceed to test step 6.
- NO – The engine turns with more than normal effort. The engine needs to be serviced.
Repair: Repair the engine. Refer to the Disassembly and Assembly manual for the engine.
Test Step 6. TEST THE INTERNAL COMPONENTS OF THE STARTING MOTOR
- Check starting motor brushes. See Testing and Adjusting, “Brush and Brush Holder – Check”.
The brushes of the starting motor are in good condition.
- OK – The brushes of the starting motor are in good condition.
Repair: Perform the component tests for the starting motor. See the proper test in the Testing and Adjusting section.
- NOT OK – The brushes are not in good condition.
Repair: Replace brushes or repair brushes. Repair the brush holder or replace the brush holder.