Ignition Unveiled - Starting System Diagnosis and Repair

Introduction

The starting system is a crucial component in a vehicle, responsible for initiating the engine operation. It consists of various elements, such as the battery, starter motor, solenoid, and associated electrical connections.

In this section, we explore the process of diagnosing and repairing issues within the starting system to ensure optimal performance and reliability. We will discuss different tasks, including performing starter current draw tests, starter circuit voltage drop tests, inspection, and testing of switches, connectors, and wires, as well as the removal and replacement of starter relays, solenoids, and the starter itself.

The aim of this section is to provide a comprehensive guide for both automotive professionals and the general public, helping them better understand and maintain their vehicle’s starting system.

Task C.1: Perform Starter Current Draw Test; Determine Needed Repairs

The starter current draw test is essential to diagnose and repair the starting system of a vehicle. This test helps to determine the condition of the starter and identify any internal engine problems. The procedure involves measuring the starter current draw, cranking speed, and cranking voltage using a suitable instrument, such as a VAT-40.

Follow this procedure:

1. Prepare the vehicle: Make sure the vehicle is in a safe and secure position with the transmission in neutral or park. Disable the ignition and fuel systems to prevent the engine from starting during the test.
2. Connect the testing instrument: Follow the manufacturer’s instructions to connect the VAT-40 or a similar testing device to the battery and starter. Ensure proper connections to avoid inaccurate readings.
3. Perform the test: Crank the engine and observe the current flow, cranking speed, and cranking voltage on the testing instrument.
4. Analyze the results: High starter current draw, low cranking speed, and low cranking voltage usually indicate a defective starter or internal engine problems, such as partially seized bearings. Low current draw, low cranking speed, and high cranking voltage suggest excessive resistance in the starter circuit.
5. Determine needed repairs: Based on the test results, identify the necessary repairs for the starter system. This may include replacing the starter, repairing internal engine components, or addressing excessive resistance in the starter circuit.

The starter current draw test is a critical diagnostic procedure for identifying issues with the starting system. By carefully analyzing the results, technicians can pinpoint the source of the problem and perform the necessary repairs. This test is crucial for ensuring the reliability and functionality of a vehicle’s starting system.

Task C.2: Perform Starter Circuit Voltage Drop Tests; Determine Needed Repairs

The starter circuit voltage drop test is a diagnostic procedure used to identify excessive resistance in the starter circuit. This test involves measuring the voltage drop across each component in the circuit while the starting motor is operating. By analyzing these measurements, technicians can determine the necessary repairs to restore optimal starter performance.

Follow this procedure:

1. Prepare the vehicle: Ensure the vehicle is in a safe and secure position with the transmission in neutral or park. Disable the ignition and fuel systems to prevent the engine from starting during the test.
2. Set up the voltmeter: Connect the voltmeter leads to the appropriate points in the starter circuit, such as the positive battery terminal and the positive cable on the starter solenoid.
3. Perform the test: Crank the engine and measure the voltage drop across each component in the starter circuit.
4. Analyze the results: Compare the measured voltage drops to the manufacturer’s specifications. Excessive voltage drops indicate high resistance in that part of the circuit, which can lead to poor starting performance.
5. Determine needed repairs: Based on the test results, identify the necessary repairs for the starter circuit. This may include replacing or repairing components, such as cables, switches, or connectors, to reduce resistance and improve starting performance.

The starter circuit voltage drop test is a valuable diagnostic tool for identifying and repairing issues in the starter circuit. By accurately measuring the voltage drop across each component and comparing it to the manufacturer’s specifications, technicians can pinpoint areas of excessive resistance and perform the necessary repairs to ensure optimal starter performance.

Task C.3: Inspect, Test, and Repair or Replace Switches, Connectors, and Wires of Starter Control Circuits

Switches, connectors, and wires in the starter control circuit play a crucial role in the vehicle’s starting system.

Regular inspection, testing, and repair or replacement of these components are essential to maintain the efficiency of the starting system. This task covers the procedures for inspecting, testing and repairing or replacing switches, connectors, and wires in the starter control circuit.

1. Visual inspection: Begin by visually inspecting the starter control circuit components for signs of damage, corrosion, or wear. Look for loose connections, frayed wires, or damaged switches and connectors.
2. Test switches and relays: Use an ohmmeter to test the switches and relays in the starting motor circuit. Connect the ohmmeter leads across the relay or switch contacts to measure the resistance. An infinite reading indicates open contacts, while a reading near zero shows closed contacts. When testing relay windings, the meter should indicate the specified resistance.
3. Inspect and test wires: Check the wires in the starter control circuit for signs of damage or wear. Use a multimeter to test the continuity and resistance of the wires. High resistance or lack of continuity indicates a need for repair or replacement.
4. Repair or replace components: Based on the inspection and test results, repair or replace any damaged or faulty switches, connectors, or wires in the starter control circuit.

Regular inspection and testing of the switches, connectors, and wires in the starter control circuit are crucial for maintaining the efficiency and reliability of the starting system. By identifying and addressing any issues with these components, technicians can help ensure optimal starting performance and prevent more significant problems in the future.

Task C.4: Inspect, Test, and Replace Starter Relays and Solenoids

Starter relays and solenoids are critical components of the starting system, responsible for controlling the flow of electrical current to the starter motor. Regular inspection, testing, and replacement of these components ensure the proper functioning of the starting system.

1. Visual inspection: Begin by visually inspecting the starter relays and solenoids for signs of damage or wear. Check for loose connections, corrosion, or other visible issues.
2. Test solenoids: Use an ohmmeter to test the solenoid windings. Connect the ohmmeter leads across the solenoid terminal and the field coil terminal to test the pull-in winding, and from the solenoid terminal to the ground for the hold-in winding. Compare the measured resistance to the manufacturer’s specifications.
3. Test relays: Connect the ohmmeter leads across the relay contacts and windings, as described in Task C.3, to measure the resistance. Compare the readings to the manufacturer’s specifications.
4. Replace faulty components: If the inspection and test results indicate a faulty relay or solenoid, replace the component with a new one, ensuring proper installation and secure connections.

Regular inspection and testing of starter relays and solenoids are essential for maintaining the efficiency of the starting system. By identifying and addressing any issues with these components, technicians can ensure the proper functioning of the starting system and prevent more significant problems in the future.

Task C.5: Remove and Replace Starter

The starter is a crucial component of the starting system, responsible for turning the engine over during the starting process. Occasionally, the starter may need to be removed and replaced due to wear or damage. Refer to the picture below for schematic details. This task covers the procedure for removing and replacing the starter.

1. Prepare the vehicle: Ensure the vehicle is in a safe and secure position with the transmission in neutral or park. Disconnect the battery to prevent accidental electrical contact during the process.
2. Remove the starter: Following the manufacturer’s guidelines, carefully remove the starter from the vehicle. This process may involve disconnecting wires, removing mounting bolts, and detaching any additional components necessary for access.
3. Inspect the new starter: Before installing the new starter, visually inspect it for any defects or damage. Ensure that it is the correct part for the vehicle.
4. Install the new starter: Following the manufacturer’s instructions, install the new starter into the vehicle. Securely attach all mounting bolts, reconnect wires, and reassemble any additional components removed during the removal process.
5. Perform post-installation tests: After installing the new starter, perform a free spin test or a current draw test to verify proper operation. Also, test the pinion gear clearance by disconnecting the M terminal and shifting the pinion gear into the cranking position. Use a feeler gauge to measure the clearance, which should typically be between 0.010 and 0.040 in (0.25 to 1.01 mm) according to the manufacturer’s specifications.

Removing and replacing a starter is an essential procedure for maintaining the proper functioning of a vehicle’s starting system. By carefully following the manufacturer’s instructions and performing post-installation tests, technicians can ensure that the new starter is correctly installed and functioning optimally.

Task C.6: Differentiate Between Electrical and Engine Mechanical Problems That Cause a Slow Crank or No Crank Condition

When diagnosing starting problems, it is crucial to differentiate between electrical and engine mechanical issues that may cause a slow crank or no crank condition. This task covers the steps to distinguish between these two types of problems and identify the root cause of the starting issue.

1. Check the battery: Begin by performing a series of battery tests to confirm the condition of the battery. Many starting problems are related to batteiy issues, and addressing any batteiy problems may resolve the slow crank or no crank condition.
2. Inspect the starter system: Perform a visual inspection of the starter system, checking for loose connectors, frayed wires, and other visible issues that may contribute to the starting problem.
3. Test the starting system: Perform tests such as the starter current draw test (Task C.i) and starter circuit voltage drop tests (Task C.2) to determine if an electrical issue is causing the slow crank or no crank condition.
4. Attempt manual engine rotation: If the engine will not turn over after completing the previous steps, use a large socket wrench to attempt to turn the crankshaft pulley nut manually. If the engine cannot be rotated, it may indicate a seized engine or other mechanical problem.
5. Inspect engine components: If a mechanical issue is suspected, perform a thorough inspection of the engine components, such as the timing belt, pulleys, and internal engine parts, to identify any issues that may cause the slow crank or no crank condition.

Differentiating between electrical and engine mechanical problems that cause a slow crank or no crank condition is crucial for proper diagnosis and repair of starting issues. By following a systematic approach and performing the necessary tests and inspections, technicians can accurately identify the root cause of the problem and take the appropriate action to resolve the issue.

The Key Takeaways

Here are the Key Takeaways from this Section:

• Perform starter current draw test to diagnose and determine necessary repairs for the starting system.
• Conduct starter circuit voltage drop tests to identify excessive resistance in the starter circuit and determine required repairs.
• Regularly inspect, test, and repair or replace switches, connectors, and wires in starter control circuits to maintain the reliability and functionality of the starting system.
• Inspect, test, and replace starter relays and solenoids to ensure proper control of electrical current to the starter motor.
• Safely remove and replace faulty starters to restore optimal starting performance and prevent potential starting problems.
• Differentiate between electrical and engine mechanical problems that cause a slow crank or no crank condition by conducting battery’ tests, visual inspections, and manual engine rotation checks.

That’s all for the starting system. Have you noticed how important visual inspections are yet? Like most jobs today a keen eye and experience will tell you what you need to know to fix a problem.

Good Luck!

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