Workshop Practice, Tools and Diagnostics
Workshop Practice, Tools and Diagnostics
This domain covers safe and accurate use of hand and power tools, torque procedures, precision measurement and a logical diagnostic process. The exam rewards evidence-based testing over parts swapping.
Core rules
- Torque is a turning moment; use the specified unit and tighten in the specified sequence, especially cylinder heads and wheel nuts.
- Precision tools include micrometers, vernier calipers, dial indicators and feeler gauges; check zero and read the scale carefully.
- Diagnostic process: verify the complaint, gather information, inspect, test, repair, then verify the repair.
- DTCs identify a circuit or system, not always the failed part; use freeze-frame data and live data to confirm.
- A scope shows signal shape and timing; a multimeter shows average values and may miss intermittent glitches.
Worked example
A metric micrometer shows 7 mm on the barrel and 34 divisions on the thimble. Each thimble division is 0.01 mm, so the reading is 7.00 + 0.34 = 7.34 mm. Read the barrel first, then the thimble, and check the vernier scale if fitted. Record the measurement with the correct resolution, not as about 7 mm.
Traps
- Using an impact wrench to tighten a torque-critical fastener.
- Reading a micrometer without checking zero.
- Treating a DTC as a direct replacement instruction.
- Back-probing a connector with a probe that spreads the terminal.
- Skipping the post-repair verification drive.