310S airbags, body and trim practice questions.

Five free practice questions on airbags, body and trim: block G of the Red Seal 310S Automotive Service Technician exam, about 10 of its 125 questions. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.

01The questions

1. Recall · Diagnoses wind noises, rattles and water leaks

   Why does a poorly sealed door top produce a whistle at highway speed even though the cabin is closed and the blower is off?

   1. The blower motor pressurizes the cabin, forcing air out at the weakest point
   2. Air moving fast over the body creates low pressure outside, drawing cabin air out through the gap
   3. Ram air pushes into the cabin through the gap because outside pressure is higher
   4. The door seal vibrates like a reed only when it is wet
   Show the answer

   B. Correct. Air accelerating around the A-pillar, mirror and roof line drops in pressure (Bernoulli effect), so the cabin is at higher pressure than the air just outside the door top. Cabin air is sucked out through any small gap and the fast, thin flow whistles. This is why an interior pressure test (blower on high, fresh-air mode, doors closed) reproduces the leak in the shop: it pushes air out the same way so a hand, smoke or soap solution can find it.

   Why not the others

   A. The blower is off in the scenario. In the shop the blower is used deliberately to create that pressure for a leak test, but on the road the aerodynamic low pressure does the work.

   C. The pressure just outside the door top and pillars at speed is lower than the cabin, not higher. Most wind noise is air leaving the cabin, which is why sealing is checked by pressurizing the interior.

   D. Seal flutter can happen dry or wet. The whistle described comes from air escaping through a gap, and it is a pressure difference that drives it.

2. Critical · Repairs wind noises, rattles and water leaks

   A body seam leak in a rear wheelhouse was sealed last week, but a water test now shows water entering at the same seam. The technician had applied new sealer over the old sealant without cleaning the area. What is the most likely reason the repair failed?

   1. The wrong colour of sealant was used
   2. Seam sealer must be applied from inside the cabin only
   3. The seam sealer needs a week to cure before it will hold water
   4. Poor adhesion: the seam was not cleaned and dried before sealing
   Show the answer

   D. Correct. Seam sealer only holds if it bonds to a clean, dry, sound surface. Old cracked sealant, road grime, salt and moisture underneath let the new bead lift and water tracks beneath it. Remove the failed sealer and any loose old material, clean and dry the metal, treat any rust, apply the sealer so it overlaps sound sealant on each side, let it cure per the label, then water-test again.

   Why not the others

   A. Colour affects appearance, not sealing. Adhesion is what keeps water out.

   B. Sealer is applied on the side the water comes from, usually the outside of the wheelhouse, and sometimes both. Location was not the problem here; preparation was.

   C. Most seam sealers skin in minutes and are water-resistant within hours. A week later a properly bonded bead is fully cured, so cure time does not explain the leak.

3. Critical · Diagnoses interior and exterior components, accessories and trim

   A power seat moves forward normally but will not move rearward, and the motor is silent when rearward is selected. Where is the fault most likely?

   1. In the seat motor's ground circuit
   2. In the seat motor's armature windings
   3. In the switch or wiring for the rearward direction
   4. In the seat track drive gears or flex cable
   Show the answer

   C. Correct. A seat motor is reversed by swapping polarity through the switch. Because the seat drives forward, the motor, its ground path, the fuse and the drive mechanism are all proven good. The only thing not shared by the working direction is the switch contact and wire that feed the opposite polarity, so that is where to test with a DMM.

   Why not the others

   A. The ground path is used in both directions on a reversible motor, so an open ground would stop the seat completely, not in one direction only.

   B. The same armature turns the seat forward without trouble. A motor with a bad armature would fail or drag in both directions.

   D. A jammed drive would usually stop travel in both directions or make the motor strain and hum. Here the motor is silent, which points to an electrical fault, not a mechanical one.

4. Procedural · Repairs interior and exterior components, accessories and trim

   A front door on bolt-on hinges with slotted holes needs to be raised about 3 mm (1/8 in) at the rear edge to correct a sag. Which is the correct sequence?

   1. Bend the hinge with a hinge tool while the bolts stay tight, then re-check gaps
   2. Raise the striker first, then move the hinges only if the door still sags
   3. Loosen the hinge bolts with the door supported, reposition it, then set the striker
   4. Shim the striker with washers and leave the hinge bolts alone
   Show the answer

   C. Correct. The door is supported on a padded jack or by a helper, the hinge-to-body (or hinge-to-door) bolts are loosened just enough to move the door, the door is shifted the required amount, the bolts are torqued and the gaps and flushness re-checked. Only after the door hangs correctly is the striker adjusted so the latch closes with normal effort. Typical body gaps are around 4 to 6 mm (5/32 to 1/4 in) and are compared side to side.

   Why not the others

   A. Bending is a technique for welded hinges that cannot be repositioned. Bolt-on hinges with slotted holes are adjusted by loosening and moving, not by bending.

   B. Adjusting the striker to lift a sagging door forces the latch to carry the door and wears the latch and striker. Alignment starts at the hinges; the striker is always last.

   D. Shimming the striker moves the latch point but does not lift the door; the sag, the uneven gap and the hinge wear are all still there.

5. Critical · Diagnoses restraint systems

   The manufacturer's inspection procedure states that a front seat belt retractor must lock when the webbing is pulled out sharply. During inspection the belt feeds out smoothly, but a sharp tug never causes it to lock. Which conclusion is correct?

   1. The webbing needs cleaning so the retractor can grip it
   2. Normal, because this retractor only locks when the vehicle decelerates or tilts
   3. The pretensioner has fired and must be reset with a scan tool
   4. The retractor's locking mechanism is faulty; replace the belt assembly
   Show the answer

   D. Correct. The webbing-sensitive lock inside the retractor is not engaging, so in a collision the belt would spool out instead of holding the occupant. Retractors are not repairable and the belt is replaced as an assembly. The vehicle-sensitive (inertia) lock should be checked as well, by tilting the retractor or a controlled brake application per service information.

   Why not the others

   A. The lock is a ratchet on the retractor spool, not friction on the webbing. Dirty webbing may feed slowly, but it does not stop the lock from engaging.

   B. The stated procedure says this belt must lock on a sharp pull, so a retractor that does not is outside specification. Vehicle-sensitive locking is checked separately, not instead.

   C. A fired pretensioner usually leaves the belt tight or the retractor locked, and it cannot be reset by a scan tool. Free-feeding webbing that will not lock is a retractor lock fault.

02Answer key

03What block G covers

This block covers restraint systems and the vehicle body. It includes airbags and the SRS, clock springs, seat belts and pretensioners, occupant classification, wind noise, rattles and water leaks, door and bumper fit, power seats and mirrors, trim removal, weatherstrips and sealers, and the latches, locks, power windows, sunroofs and liftgates.

The Red Seal Occupational Standard names this block “Diagnoses and repairs restraint systems, body components, accessories and trim”. It carries 8% of the exam, about 10 of the 125 questions, split across two tasks. The share column is each task's weight within the block, as the standard publishes it.

04What the questions turn on

Working safely around airbags

Before unplugging any airbag connector, disconnect the battery negative and wait the specified time for the reserve capacitor to drain. Carry an undeployed module with its cover away from your body and set it cover-up on the bench.

Testing an SRS circuit

A load tool stands in for the airbag so the circuit can be checked without a live inflator. If the code clears, the airbag is at fault. If it stays, check the wiring, connector or clock spring feeding it.

Finding water and wind leaks

Water-test from the lowest point upward, since the first leak found is the entry point. Taping over a gap on a road test confirms a whistle source, and a paper drag test shows where a door seal is not compressed.

Hinges first, striker last

Door alignment is corrected at the hinges first and the striker last. Play at the rear edge of a lifted door means worn hinge pins. A door with correct gaps that only reaches the first latch position needs the striker moved.

05The other blocks

The 310S exam has eight blocks. Each has its own page of free questions:

The 310S Automotive Service Technician practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.