Book summary “Automotive Technician Training”: summary

Introduction

Modern vehicles combine complex mechanical components with intricate electronic networks. You face the constant challenge of diagnosing elusive faults, handling high-voltage systems safely, and maintaining precision across every vehicle subsystem. Without a structured foundation, repairs lead to wasted time and severe safety hazards.

Mastering automotive systems requires strict adherence to diagnostic standards, technical limits, and safe workshop practices.

Tom Denton provides a comprehensive guide to professional vehicle maintenance and repair. You will learn the core principles of workshop safety, engine systems, electrical diagnosis, chassis mechanics, and transmission servicing.

Consider these questions as you read:

• How do you maintain a safe and organized workshop environment?
• What are the correct procedures for diagnosing electrical faults and charging systems?
• How do you measure and service mechanical limits on brakes and engines?

1. Workshop Standards and Safety

Thorough documentation and rigorous adherence to hand tool safety rules protect you and ensure successful maintenance operations.

Accurate record-keeping of vehicle details, faults, and technical data ensures that manufacturers approve warranty claims. Inaccurate job cards lead to rejected payments by manufacturers. Thoroughly completed job cards are essential for student assessment and workplace warranty claims.

You should complete these records during your work:

• Copy and fill in a blank job card alongside the task.
• Record relevant vehicle details, the fault, and the rectification procedure.
• Write down a description of the completed work, technical data sourced, and difficulties encountered.
• Document health and safety issues addressed, such as waste disposal or spillages.

Job Card Documentation

Tom Denton discusses Vocational Qualifications and assessor reports alongside basic workshop records. You will find that precise notes protect your work from rejected claims.

Hand Tool Safety

Tools must only be used for their intended purposes with correct sizing. Proper mechanical habits maintain tool longevity and personal safety. Adhering to basic hand tool rules prevents accidents and equipment damage in the workshop.

Guidelines are explicitly sourced from information provided by Snap-on.

You must follow these practices to avoid injury:

• Only use a tool for its intended purpose.
• Always use the correct size tool for the job you are doing.
• Pull a spanner or wrench rather than pushing whenever possible.
• Do not use a file or similar without a handle.
• Keep all tools clean and replace them in a suitable box or cabinet.
• Do not use a screwdriver as a pry bar.

2. Engine Ancillaries and Cooling

Controlling coolant concentration and drive belt tension prevents severe engine damage and mechanical failures.

Coolant and Antifreeze

Coolant antifreeze concentration must be strictly controlled because exceeding specific thresholds reduces frost protection. Ethylene glycol content should not exceed 50% to 60%, as higher levels do not improve frost protection and concentrations over 70% actually diminish protection.

You must maintain the correct fluid mix using specific servicing steps:

• Mix new coolant to the specified mixture of water and antifreeze with inhibitors or use a premixed coolant.
• Measure antifreeze content with a hydrometer and adjust for temperature.
• Check that ethylene glycol content does not exceed 50% to 60%.

Drive Belt Maintenance

Drive belt tension and free play must be accurately measured to prevent slipping, whining, or slap against covers. Improper belt tension causes mechanical issues; overly tight belts create a whining noise while loose belts slap against covers or cause glazing of drive faces due to slippage.

You need to verify the installation according to mechanical guidelines:

• Identify the drive belt for the alternator or water pump as V, multi-vee, or serpentine.
• Check that free play is about 12 mm or 1/2 inch on the longest side for V belts.
• Use a tension gauge for multi-vee belts or adjust so the belt can be twisted through 90 degrees on the long side.

3. Electrical and Charging Systems

Rigorous battery testing, component replacement protocols, and alternator verification maintain the integrity of vehicle electrical power.

Battery Testing and Service

Battery state of charge and capacity must be verified through specific hydrometer readings and high rate discharge tests. Battery health is assessed by comparing specific gravity and voltage readings. Fully charged conventional lead-acid batteries and maintenance-free batteries exhibit specific voltage and specific gravity thresholds.

• Disconnect both battery leads, earth or ground first.
• Check the state of charge using a hydrometer and digital voltmeter.
• Carry out a high rate discharge test if readings are correct, setting the discharge rate up to 3x the Ah rate for a maximum of 15 seconds.

A near fully charged battery gives a hydrometer reading of 1.28. Conventional lead-acid batteries reach a fully charged voltage of 13 volts to 13.2 volts. Maintenance-free batteries show a fully charged voltage of 12.8 volts.

Proper battery servicing involves safety precautions, cleaning terminals, checking electrolyte levels, and verifying the state of charge. Before cleaning or removing a battery, you must install a memory keeper to protect electronic control unit settings and car entertainment systems before disconnecting the ground lead. Terminals are cleaned with a wire brush and hot water, followed by cold water rinsing to protect paintwork, then dried and coated with battery grease or petroleum jelly.

• Fit a memory keeper and disconnect the earth/ground lead if terminals need cleaning.
• Clean battery posts and terminals using a wire brush and hot water as required, followed by copious amounts of cold water.
• Dry the terminals and posts, then apply battery grease or petroleum jelly.
• Top up unsealed batteries with deionized water to a few millimetres above the plates.
• Check state of charge using a voltmeter or hydrometer and recharge off the vehicle if necessary.
• Refit battery and terminals securely, restoring electronic memory functions if no keeper was used.

Starting and Charging Systems

Removing and refitting electrical components requires systematic disconnection, managing fluid levels, and maintaining connection records. The author outlines a generic sequence for component removal starting with power isolation and memory preservation, ensuring fluid containment, and reversing the sequence during refitting with the earth lead always reconnected last.

• Fit a memory keeper to prevent changing stored settings in electronic control units and car entertainment systems.
• Remove the battery earth/ground lead.
• Disconnect supply connections, remove casing clamps, and keep batteries level to prevent spilling sulphuric acid electrolyte.
• Disconnect supply wires and make notes or sketches of connections to save time during refitting.
• Remove obstructing parts like exhaust shields for easy access before disconnecting components like alternators.
• Disconnect linkages and peripherals, undo mountings, remove the unit, and always reconnect the earth/ground lead last during refitting.

Starter motor overhaul requires meticulous inspection of drive pinions, armatures, and commutators, followed by rigorous bench testing before refitting. Technicians must inspect flywheel ring gears for uneven wear through the starter aperture, strip down solenoids and brushes, and execute isolated bench tests using jump leads to separately verify solenoid engagement and motor rotation.

• Disconnect battery ground, label and disconnect solenoid cables and main supply feed, remove obstructing parts, and unbolt the starter motor.
• Inspect the drive pinion, one-way clutch, casing, and starter ring gear on the flywheel by turning the engine at least one full revolution.
• Strip the motor in a bench vice by removing through bolts, rear cover, brushes, solenoid, and armature as needed.
• Conduct a bench test by securing the starter in a vice, connecting a negative jump lead to the casing, and touching the positive lead to terminals to test solenoid clicking and motor running speed separately.

Replacing an alternator involves belt tension management, rotational marking, and post-installation electrical output verification. Technicians disconnect power, slacken adjuster straps, mark belt rotation direction, inspect drive belts and pulleys for glazing or wear, and verify generator charging output using digital voltmeters and clamp-on ammeters.

• Disconnect the battery earth or ground lead and unplug or disconnect wiring from the rear of the alternator.
• Slacken securing bolts and drive belt adjuster strap bolts, mark belt rotation direction, slacken belt tension, and remove the belt.
• Inspect drive belt and pulleys for wear, damage, and slipping or side glazing.
• Refit components in reverse order, adjust drive belt tension, and run the engine to check that the generator warning light extinguishes as speed increases.
• Connect a digital voltmeter and clamp-on ammeter to verify that alternator output matches manufacturer data.

4. Chassis and Brakes

Braking safety depends on strict adherence to mechanical wear limits and precise installation procedures. You must monitor friction material thickness and control hydraulic pressure during service operations.

Measuring brake pad thickness limits and disc run out guarantees braking safety and performance under load.

Brake Pad Replacement

Disc brake pads require replacement when friction material falls below specific thickness limits to maintain braking safety. Manufacturers provide recommendations, but pads generally need replacement when linings thin past 1.5 mm. Pistons must be pressed back, which requires monitoring brake fluid levels in the reservoir to prevent overflow.

You follow these steps to service the assembly:

• Jack up and support the vehicle on stands and remove wheels.
• Inspect brake pads and replace if the lining is less than 1.5 mm.
• Remove some brake fluid from the reservoir if necessary before pushing the piston back.
• Undo caliper piston fixing bolts and withdraw pads as a set across both sides.
• Push the caliper piston fully home using a G/C clamp.
• Pump the brake pedal until it feels hard to position the pads before lowering the vehicle.

Brake Disc Inspection

Brake discs must be measured for thickness variations and run out limits to detect excessive wear or warping. Disc surfaces can develop small grooves during normal use, but grooves deeper than 0.4 mm are considered excessive. Dial indicators are used to measure run out, where limits typically cap at 0.15 mm.

You use specific measuring tools to assess component integrity:

• Inspect the disc surface for cracking and grooves.
• Measure the thickness of the disc at several different places using a micrometer.
• Mount a dial gauge on a stand with the plunger running about 15 mm in from the outer edge.
• Zero the gauge, rotate the disc, and compare readings against maximum allowable run out limits.

5. Transmission and Body Systems

Systematic servicing of automatic transmissions, lighting, safety restraints, and body electronics ensures full vehicle functionality.

You must handle automatic transmissions with strict adherence to recommended fluid types and cleanliness. Using incorrect fluid types can cause severe damage to automatic transmissions.

Servicing involves draining the fluid, cleaning or replacing the filter, inspecting pan residues for fault diagnosis, and verifying fluid levels with specific engine running conditions.

Follow these steps to service an automatic transmission:

• Warm up the transmission and raise the vehicle on a hoist.
• Remove the drain plug or undo the sump bolts carefully to drain oil into a catch pan.
• Remove the transmission fluid filter or screen to clean or renew it.
• Clean the sump thoroughly inside and out, ensuring old gasket traces are removed.
• Refit the sump with new gaskets, tighten bolts evenly to specified torque, and refill with the correct quantity of recommended oil.
• Apply the handbrake, start the engine, move the lever through all positions, and recheck the fluid level.

Lighting and Security Systems

Flasher units indicate blown bulbs through altered flash rates and are typically modular units located near fuse boxes or steering columns. Flasher units are designed to operate at different speeds when a bulb fails. Most replacement units simply pull out from their sockets, but technicians must verify that correct, more powerful replacement units are installed if towing sockets are present.

Carry out this procedure when replacing a flasher unit:

• Locate the turn signal flasher unit in the fuse box or on the steering column.
• Remove covers or shrouds as necessary and pull the flasher unit straight out of the socket.
• Push the correct new unit into the holder, taking care to use more powerful units if a towing socket is fitted.
• Verify that indicators and hazard lights operate correctly after renewal.

Central door locking and alarm system tests require manual, remote, and interior sensor verification procedures. Technicians use scan tools to check stored fault codes, operate locking mechanisms manually with keys from multiple doors and via remote controls, and verify interior movement sensors or door-opening intrusion alarms.

Test central door locking and alarms using this sequence:

• Use a scan tool to check for alarm and central locking stored fault codes.
• Close all doors and operate central locking from the driver's door lock manually using the key, checking double locking if fitted, then repeat with remote key and passenger door lock.
• Open a window, fully lock the car, and reach inside to trigger movement sensors or open the door from the inside to verify alarm sounding.
• Reset the alarm using the remote or key in the driver's door.

Body Electrical and Safety

Seatbelts must undergo rigorous physical inspection and dynamic testing to ensure webbing integrity, locking mechanisms, and retraction functions.

Seatbelt systems may include collision tensioners that require careful handling. Technicians must inspect webbing for physical damage, verify latch security, ensure full retraction, and conduct dynamic vehicle braking tests.

Inspect and service seatbelts with this exact method:

• Check for twisted webbing or contamination and adjust or clean as required.
• Fully extend each belt to inspect for cuts, damage, broken threads, colour fading, and bowed webbing, renewing damaged belts according to manufacturer procedures.
• Insert the tongue into the buckle and pull hard to ensure it locks; push the release button to check easy release.
• Pull each belt fully out to verify spring retraction and pull sharply to check lock-up.
• Drive away from traffic and brake sharply from about 10 mph/16 kph to ensure the driver's belt locks and holds position.

Servicing body electrical systems covers functional tests of visibility aids, safety restraints, infotainment, and convenience features. The procedure outlines checks for wipers, washers, horns, locks, windows, sunroofs, and safety systems like airbags, requiring technicians to disarm and rearm supplementary restraint systems properly.

Complete the body electrical service using these steps:

• Check wiper and washer operation, top up fluid, inspect wiper blades, and adjust or clean washer jets using a pin.
• Verify audible warning device operation by pressing the horn button.
• Check smooth operation of electric or manual windows, door locks, and sunroofs.
• Disarm the supplementary restraint system (SRS) airbag for the duration of the service and rearm it afterwards, checking warning lights and scanning with a scan tool.
• Test the in-car entertainment system aerial and speaker reception, resetting customer preferences.
• Road test the vehicle to check cruise control operation.

Replacing a windshield wiper motor involves precise marking of linkage positions, parking the motor electrically, and testing linkage movement prior to arm attachment. When replacing a motor accessed from the engine compartment, technicians must mark component positions with masking tape, remove cowlings, extract the motor and linkage assembly, and re-park the motor before final arm installation.

Refit a wiper motor following these steps:

• Switch off ignition, mark wiper blade positions with masking tape, and remove wiper arms.
• Raise bonnet, remove rubber strips, covers, and wiper motor cover panels to access the wiring harness plug and spindle nuts.
• Slacken and remove motor mounting bracket screws, then manoeuvre the motor and drive linkage out of the vehicle.
• Connect the motor to the harness without the linkage and run it until it stops in the parked position, then disconnect.
• Refit the crank and linkage, test movement, and finally refit arms, blades, and check spray operation.

Instrument cluster and warning light verification requires stationary ignition checks followed by engine start and road testing. Technicians verify baseline readings for gauges and warning lights with the ignition on, check extinction of pressure and charge lights upon engine start, and validate speedometers through road tests.

Check main instruments and warning lights with this procedure:

• Switch ignition on without starting the engine to verify that rev-counter and speedometer read zero or less, oil pressure and charge warning lights are on, and fuel and temperature gauges read appropriately.
• Ensure transmission is in neutral or park and start the engine.
• Verify oil and charge warning lights go out as engine revs rise and stay out at idle speed.
• Compare rev-counter readings with a test meter and road test to check speedometer operation.

10 Key Ideas

1. Accurate completion of job cards with vehicle details, faults, technical data, and health and safety issues is essential for workplace warranty claims and student assessments.
2. Hand tools must only be used for their intended purposes with correct sizing, such as pulling wrenches rather than pushing and keeping tools clean.
3. Coolant antifreeze concentration must be strictly controlled with ethylene glycol content not exceeding 50% to 60% to prevent diminished frost protection.
4. Drive belt tension and free play must be accurately measured to prevent slipping, whining noises, or slap against covers.
5. Battery health is assessed by comparing specific gravity and voltage readings through hydrometer tests and high rate discharge tests.
6. Brake pads require replacement when friction material thins past 1.5 mm, and brake discs must be measured for thickness variations and run out limits.
7. Automatic transmissions must be serviced using recommended fluid types, cleanliness protocols, and proper fluid level checks with the engine running.
8. Flasher units indicate blown bulbs through altered flash rates and can be easily replaced by pulling them straight out of their sockets.
9. Seatbelt systems must undergo physical inspections for webbing damage, latch security checks, spring retraction verification, and dynamic braking tests.
10. Starter motors and alternators require systematic removal, meticulous component inspections, bench testing, and post-installation output verifications using digital multimeters.