B5 Collision — Mechanical & Electrical — practice test

High-yield B5 topics

The material that shows up year after year. If you're short on time, start here.

• Alignment angles and what each one actually does. Camber and toe are the tire-wear angles; caster is the pull and return angle and is NOT a wear angle. A pull with even tire wear points at cross-caster or cross-camber (roughly 0.5 degree or more side to side). Memory steer points at a bind. A crooked wheel with straight tracking is a centering problem, not a toe spec problem. Setback and thrust angle are the two that expose a bad frame pull - thrust angle out of spec is why the car dog-tracks, and it is why the rear gets aligned first.
• Steering and suspension parts that are replace-only. Bent knuckles, control arms, struts, tie rods, and any collapsed crush zone in a subframe get replaced, never heated and straightened. Welding or straightening a MacPherson strut is a hard no. Any hit at the wheel end means you inspect the whole corner, including the bearing, the hub flange runout, and the strut tower, not just the visible bend.
• SRS handling: disable, wait, never reuse. Disconnect battery negative, then wait the manufacturer stand-down time (varies by maker, commonly one to ten minutes) - the correct test answer is always 'follow the service information,' not a memorized number. Never apply power or an ohmmeter to a squib. Deployed bags, pretensioners, the control module, and the clockspring are replacement items. Impact sensors and the module mounting points are structural: a bent bracket changes deceleration sensing.
• Electrical diagnosis with a meter, not a test light. Voltage drop is the money skill: about 0.1 V max across a ground connection, roughly 0.2 V through a switch or connector under load, about 0.5 V total on the ground side of a circuit. Correct voltage at rest but no response under load equals high resistance. Full source voltage across an open load is normal. Know parasitic draw testing (commonly 25 to 50 mA once modules sleep) and that a harness the maker calls replace-only does not get a crimp splice buried in it.
• A/C service and federal rules. Recover before opening, never vent, never mix refrigerants; Section 609 certification is required to purchase and handle refrigerant. A condenser hit means recover, replace, and return the correct oil amount for that component. A system left open needs the receiver/drier or accumulator replaced plus a deep vacuum (roughly 29 in. Hg, 500 microns) to boil out moisture. R-1234yf requires dedicated, separate equipment.
• Cooling, drivetrain, and belt hardware after the hit. A pushed radiator support changes fan clearance and hose routing; pressure test the system and the cap separately, and remember electric fans can run with the key off. A bent driveshaft, cracked flex plate, or shifted subframe changes driveline angle and shows as a vibration that changes with load. Belts that were occupied during a deployment event get replaced, and anchors get torqued to spec into undamaged structure.

Where techs lose points on B5

Good technicians miss these — not from lack of skill, but because the question is built to catch them.

• Blaming caster for tire wear. The classic look-alike answer: the car pulls, the tire is feathered, and caster is sitting right there in the answer list. Caster does not wear tires. Feathering is toe, shoulder wear is camber, and a pull with no wear is caster, road crown, or tire conicity. They put caster in on purpose.
• Chasing the front end when the rear is the problem. If thrust angle is out, setting front toe just centers the wheel on a car that still dog-tracks. Rear first, always. The reverse trap: a crooked wheel after a repair is not automatically a spec fault, it can be a wheel reinstalled off the splines or a tie rod adjusted unevenly.
• Assuming battery disconnect equals SRS safe. Pulling the negative cable does not instantly drain the module's reserve capacitor, and it does not make a live undeployed bag safe to toss on a cart. The right answer is the maker's disable procedure plus the wait time, then handle the module face away from you. And ohming a squib is a deployment, not a test.
• Treating a corroded terminal as a wire problem. Techs replace the wire, the fault comes back. In a collision harness the resistance almost always lives at the terminal or the ground stud behind the fender liner - voltage drop under load finds it, a static ohm check or a test light does not. Same logic on HVAC: weak cooling after a front hit is usually blocked condenser airflow or a wrong charge, not a bad compressor.

A study plan that works for B5

Roughly two weeks of real preparation, in the order that actually builds on itself.

1. Days 1-4: Alignment and steering. Drill the angles until you can state cold which are wear angles, which are directional, which are non-adjustable on common platforms, and what thrust angle and setback tell you about a bad pull. Then run 40 to 50 questions on suspension and steering alone - it is the biggest single slice of the test.
2. Days 5-8: Electrical. Make voltage drop reflex: 0.1 V ground, 0.2 V connector, 0.5 V circuit ground side. Practice on a real wiring diagram and say out loud where the leads go for an open, a short to ground, and a high-resistance fault. Add parasitic draw and OEM wire repair rules.
3. Days 9-11: Restraints and HVAC. These are procedure and law, not theory - memorize SRS disable/wait/handle, what is replace-only after a deployment, and the 609 recovery, evacuation, and oil-return rules including R-1234yf equipment separation. Best points per hour on the whole test.
4. Days 12-14: Brakes, cooling, drivetrain, then full-length timed practice. Review every miss by task area, not by individual question. If the same category burns you twice, go back to that block instead of grinding more random questions.

Sample B5 questions

Straight from the bank — answers highlighted, with the explanation underneath.