205D - Cranking System Control Circuits

Question 1

What are some commonly used cranking motor safety switches?

Answer 1

• Neutral switch
• Clutch position switch
• PTO disengagement switch
• Electronic controlled circuits

205D pg. 7

Question 2

Are cranking motor safety switches connected in series or parallel with the cranking system magnetic switch coil?

Answer 2

Series

205D pg.

Question 3

How is the clutch position safety switch connected to the cranking circuit magnetic switch?
Is it a normally open or normally closed switch?

Answer 3

• Connected in series
• Normally open

205D pg. 8

Question 4

How is the PTO disengagement safety switch connected to the cranking circuit magnet switch?

Is it a normally open or normally closed switch?

Answer 4

• Connected in series
• Normally closed

205D pg. 8

Question 5

How are cranking motors typically protected from over cranking and melting the internal components?

Answer 5

A normally closed thermostat in series with the magnetic switch coil. Mounted in the back of the starter motor.

205D pg. 10

Question 6

What are the two main functions of a cranking motor solenoid switch?

Answer 6

1) Shift the drive assembly into mesh with the engine gear ring.
2) Close the electrical circuit between the batteries and cranking motor windings.

Two functions are sequential.

205D pg. 11

Question 7

When a cranking motor solenoid switch is de-energized, what moves the drive assembly out of mesh with the engine ring gear?

Answer 7

Return spring in the solenoid

205D pg. 12

Question 8

What two windings are in a cranking motor solenoid switch?

Answer 8

• Pull-in winding (large diameter wire)
• Hold-in winding (small diameter wire)

205D pg. 13

Question 9

How do cranking motor solenoid switch windings differ from each other?

Answer 9

Pull-in:
- Larger diameter wire
- Higher current flow

Hold-in:
- Smaller diameter wire
- Less current flow

205D pg. 13

Question 10

How are cranking motor magnetic switches generally positioned to reduce accidental engagement by road shock?

Answer 10

Coil & plunger positioned 90 degrees to vehicle motion.

205D pg. 17

Question 11

How many ampere turns of electromagnetic force can a 700 turn coil winding produce if it has a 12V source and 12Amps of current conducted through the coils?

Answer 11

Ampere Turns = Current * #Turns
Ampere Turns = 12A * 700
Ampere Turns = 8400

205D pg. 13

Question 12

What conditions sensed by the electronic control module could prevent the cranking and starting of a vehicle?

Answer 12

• Potential theft of vehicle
• Transmission in gear
• Low engine oil level
• Low battery voltage

205D pg. 9

Question 13

During engagement, the starter solenoid pull-in winding has current flowing from _________ to ________.

Answer 13

From the S terminal to the M terminal and then through the cranking motor electrical windings to ground.

205D pg. 14

Question 14

What are the two design styles of cranking motor magnetic switches relating to their ground terminal?

Answer 14

• Internal ground terminal
• Isolated ground terminal

205D pg. 16

Question 15

True/False
The starter solenoid hold-in windings are grounded to the starter solenoid housing or to the starter motor ground stud.

Answer 15

True

Question 16

True/False
Low current draw and low free-speed could be the result of a poor connection at the magnetic switch.

Answer 16

False.
The magnetic switch does not carry the high current for cranking the motor. It only controls the S terminal to activate the starter solenoid.