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newSchoolWorks.com › VoTechWorks › Transportation › Automotive Technology › Externship / Worksite Placement – Automotive Technology › Lesson 2
TRN-AUTO19-10 · Lesson 2 · 280 clock hours · lab

Supervised Technical Work – Core System Repairs

Objective. The student will perform diagnosis and repair tasks on customer vehicles spanning at least four ASE A-series system areas (A1 Engine Performance, A2 Automatic Transmission, A3 Manual Drivetrain, A4 Suspension/Steering, A5 Brakes, A6 Electrical/Electronics, A7 HVAC, A8 Engine Repair) at the technician's direction, meeting the shop's quality and time standards on at least 80% of assigned jobs.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a certified examiner or master technician in the trade or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Supervised Technical Work – Core System Repairs

Your externship is where classroom knowledge becomes trade competence. During this lesson block you will perform actual diagnosis and repair on customer vehicles across at least four ASE A-series system areas, working under the direction of a journeyman or master technician. The goal is straightforward: meet the shop's quality and time standards on at least 80 percent of your assigned jobs while building the professional habits that define a career technician.

Starting Every Job Right: The Repair Order

Each morning, accept the repair orders your supervising technician assigns. Before touching a vehicle, open the shop management system and pull the vehicle's service history. History tells you what has already been done, what parts are under warranty, and whether a complaint is recurring. Next, open the shop information system—ALLDATA, Mitchell 1, or equivalent—and retrieve the correct service data for that year/make/model/engine: wiring diagrams, torque specs, fluid capacities, and any Technical Service Bulletins (TSBs) related to the complaint. Never assume a spec from memory; verify it in the source.

Document every job in your field log: the system area (A1 through A8), the fault found, every part replaced with its part number, and the actual labor time you spent. This log is your proof of competency and is reviewed at the midpoint observation and at final evaluation.

Selecting and Using Test Equipment

Choose tools based on the system you are diagnosing:

Calibrate or zero each instrument before use. A mis-zeroed gauge or an uncalibrated scan tool PID can send you down the wrong diagnostic path and cost the shop and the customer time and money.

Diagnostic Process: Think Before You Turn Wrenches

Professional diagnosis follows a logical sequence. Verify the customer complaint—reproduce it yourself whenever safe. Gather evidence: DTCs, live data, visual inspection. Form a hypothesis about the most likely cause. Test that hypothesis with the least invasive test first. Confirm the root cause before ordering parts. Repair, then verify the repair corrected the original complaint and did not introduce a new concern.

During your monthly mentoring sessions, your journeyman will walk through this path with you on a complex complaint. After each session, write a half-page reflection in your field log describing what you originally thought, what the correct path was, and what you will do differently next time. These reflections are evidence of professional growth.

Technician Verification and No-Comeback Standard

Before any vehicle leaves your bay, the supervising technician must verify your work. This is not a sign of distrust—it is the industry's quality gate. A "comeback" is a vehicle that returns with the same complaint or a new complaint caused by the repair. Comebacks cost the shop time, damage customer trust, and are tracked against your performance record. Aim for zero comebacks. Check torque specs twice. Road-test the vehicle yourself and confirm the symptom is gone before calling the job done.

Midpoint Coordinator Observation

At approximately 140 hours into this lesson block, your school coordinator will visit the shop and observe you complete one full repair task—from work order intake through road-test confirmation. The coordinator scores you on the school's externship skills rubric across four areas: safety, diagnostic process, repair quality, and shop communication. All safety categories must score "meets standard" or higher; the total rubric score must be 70 percent or above to pass. Attach the written feedback sheet to your field log immediately after the visit.

Safety Is Non-Negotiable

Every task in a service bay carries hazard. Follow these standards without exception:

Passing This Lesson Block

You pass when your field log shows a technician quality-check pass rate of at least 80 percent across all completed jobs and your midpoint coordinator rubric total is 70 percent or higher with no safety category below "meets standard." Both conditions must be met. Keep your field log current every day—waiting until the end of the week to fill in entries is how details get lost and how quality rate calculations become inaccurate.

Key terms10

Repair Order (RO)The shop document that authorizes and describes the work to be performed on a specific vehicle; it records the customer complaint, labor operations, parts used, and labor time.
Diagnostic Trouble Code (DTC)A standardized alphanumeric code stored by a vehicle's on-board computer when a monitored circuit or system falls outside its acceptable range; retrieved with a scan tool via the OBD-II port.
Freeze-Frame DataA snapshot of engine and system operating conditions (RPM, load, coolant temperature, etc.) captured by the PCM at the moment a DTC was set; helps the technician reproduce and diagnose the fault.
Technical Service Bulletin (TSB)A manufacturer-issued document that describes a known vehicle concern, its root cause, and the approved repair procedure; not a recall but important diagnostic guidance found in shop information systems.
Voltage Drop TestA DVOM test performed on a circuit under load to find excessive resistance in wiring, connectors, or grounds; acceptable voltage drop limits vary by circuit type and manufacturer specification.
ComebackA vehicle that returns to the shop with the same complaint that was supposedly repaired, or with a new complaint caused by the repair; comebacks are tracked as a key measure of technician quality.
Discard SpecificationThe minimum allowable thickness (or diameter) of a brake rotor or drum set by the manufacturer; a component at or below this dimension must be replaced, not machined.
Lockout/Tagout (LOTO)An OSHA-required safety procedure that uses physical locks and warning tags to ensure a machine or vehicle system cannot be energized or pressurized while someone is performing service on it.
OBD-II (On-Board Diagnostics, Second Generation)The federally standardized vehicle diagnostic interface required on US passenger cars and light trucks since 1996; provides a common 16-pin DLC port and standardized PIDs and DTCs across manufacturers.
Field LogThe student's externship journal documenting each completed repair order including system area, fault found, parts and part numbers, labor time, and mentoring session reflections; primary evidence for competency evaluation.

Worked examples4

1. A brake rotor measures 28.4 mm with a micrometer. The manufacturer's minimum thickness specification is 28.0 mm and the manufacturer's discard specification is 27.0 mm. The shop's lathe will remove 0.5 mm per side (1.0 mm total) in a standard cut. Can the rotor be safely machined and returned to service?
  1. Step 1 – Identify the current thickness: 28.4 mm.
  2. Step 2 – Calculate thickness after machining: 28.4 mm − 1.0 mm (total cut) = 27.4 mm.
  3. Step 3 – Compare to the minimum thickness specification (28.0 mm): 27.4 mm is less than 28.0 mm.
  4. Step 4 – Because the post-cut thickness falls below the manufacturer's minimum thickness, the rotor cannot be machined and returned to service.
Answer: No. After the standard cut, the rotor would measure 27.4 mm, which is below the minimum thickness of 28.0 mm. The rotor must be replaced.
2. You perform a voltage drop test on the ground side of a fuel injector circuit with the engine running. The DVOM reads 0.42 V across the ground wire. Most manufacturers specify a maximum allowable voltage drop of 0.1 V on a ground circuit. How much excessive resistance is indicated, expressed as a voltage difference, and what action is required?
  1. Step 1 – Record the measured voltage drop: 0.42 V.
  2. Step 2 – Identify the specification: maximum 0.1 V.
  3. Step 3 – Calculate how far the reading exceeds spec: 0.42 V − 0.10 V = 0.32 V above the allowable limit.
  4. Step 4 – A reading 0.32 V above spec indicates significant resistance in the ground path (corroded connector, loose ground bolt, or damaged wire). Further inspection and repair of the ground circuit is required before replacing the injector.
Answer: The measured drop exceeds spec by 0.32 V. The ground circuit has excessive resistance and must be inspected and repaired—the injector itself should not be condemned until the ground fault is corrected.
3. Your field log shows you completed 27 repair orders during the first 10 weeks of your externship. The supervising technician issued a quality-check pass on 21 of them. What is your current quality pass rate, and are you currently meeting the 80% standard?
  1. Step 1 – Identify total jobs completed: 27.
  2. Step 2 – Identify jobs that received a quality-check pass: 21.
  3. Step 3 – Calculate pass rate: 21 ÷ 27 = 0.7778, which rounds to 77.8%.
  4. Step 4 – Compare to the required standard: 77.8% is below the required 80%.
Answer: Your current quality pass rate is approximately 77.8%, which is below the 80% standard. You need to focus on reducing comebacks and errors on upcoming jobs to bring the rate up before the final evaluation.
4. A customer's A/C system holds 550 g of R-134a per the underhood label. The recovery machine removed 310 g during evacuation. After completing the repair, how many grams of refrigerant must be charged to bring the system to the specified capacity?
  1. Step 1 – Identify the specified system capacity: 550 g.
  2. Step 2 – Identify the amount recovered: 310 g.
  3. Step 3 – Calculate the charge needed: 550 g − 310 g = 240 g.
  4. Step 4 – Confirm that the recovery machine's scale is zeroed before charging; add 240 g of R-134a to restore the system to the manufacturer's specification.
Answer: 240 g of R-134a must be added to bring the system to the manufacturer's specified capacity of 550 g.

The math in this lesson2

Learners compute quality-check pass rate from repair orders and refrigerant to recharge from label capacity.
7.RP.3N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Accept repair orders assigned by the supervising technician each day; for each job, retrieve vehicle history in the shop management system, gather the correct service information from the shop's information system (such as ALLDATA or Mitchell 1), select and calibrate needed test equipment (scan tool, multimeter, pressure gauges, brake lathe, A/C recovery machine, or alignment rack as applicable), and complete the repair with technician verification before returning the vehicle to the service lane—document each job in the field log including system area, fault found, parts replaced (with part numbers), and labor time. · Participate in at least two documented technician mentoring sessions per month in which the journeyman reviews the student's diagnostic reasoning on a complex vehicle complaint (e.g., an intermittent no-start or a brake pull), walks through the correct diagnostic path using a scan tool or wiring diagram, and has the student re-attempt the diagnosis independently; student writes a half-page reflection in the field log after each session. · At the midpoint of this lesson block (approximately 140 hours), complete the school coordinator's on-site observation visit: the coordinator watches the student perform one complete repair task from work order intake through road-test confirmation, scores the student on the school's externship skills rubric (safety, diagnostic process, repair quality, shop communication), and provides written feedback that the student attaches to the field log.
Materials: Host employer's lift-equipped service bays, vehicle scan tools (professional-grade, e.g., Snap-on, Autel, or equivalent), DVOM, brake lathe, A/C recovery/recharge station, alignment rack, torque wrenches, specialty tools as required by job, shop information system (ALLDATA or Mitchell 1 or equivalent), repair orders, school externship skills rubric, field log journal, PPE.
Check: Student achieves a technician quality-check pass (vehicle returned correctly repaired with no comeback) on at least 80% of completed jobs tracked in the field log; mid-point coordinator observation rubric scores all safety categories 'meets standard' or higher. Pass: 80% job quality rate documented in log AND coordinator observation rubric total score ≥ 70%.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

ASE A1 Engine Performance / General Diagnostic Process
1. Before beginning diagnosis on a vehicle complaint, a technician should FIRST:
ASE A6 Electrical/Electronics
2. A voltage drop test on a starter motor feed cable reads 0.8 V with the engine cranking. Most manufacturers allow a maximum of 0.5 V on a high-current feed cable. What does this reading indicate?
ASE A5 Brakes
3. When using a brake lathe, the technician must verify that the rotor's thickness after machining will:
ASE A7 Heating and Air Conditioning
4. A student is about to open an A/C system to replace a leaking condenser. What is the FIRST safety and environmental step required?
ASE A5 Brakes / General Diagnostic Process
5. During an externship mentoring session, the journeyman technician finds that the student replaced a wheel speed sensor without first checking for a broken tone ring or damaged wiring harness. This represents a failure to:
ASE A4 Suspension and Steering
6. An alignment is completed on a customer's vehicle. The technician should record which data set in the repair order to document the job properly?
ASE A1–A8 General / Program Competency Standard
7. A student's field log shows 15 completed jobs with 11 quality-check passes. The midpoint coordinator observation rubric total score is 74%, and all safety categories scored 'meets standard.' Does the student currently meet the passing criteria for this lesson block?
ASE A6 Electrical/Electronics / Safety
8. Which of the following describes the correct lockout/tagout (LOTO) practice when disconnecting a vehicle battery to perform an airbag module replacement?
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