A4 is the shortest of the common A-series tests — 40 scored questions plus 10 unscored research questions, 60 minutes — and it is the one where geometry does most of the failing. If you can mount and balance in your sleep but could not explain what negative caster does to steering return, this guide is aimed at you.
Where the questions actually are
ASE splits A4 almost evenly across three big areas and leaves a small slice for wheels and tires:
- Steering systems diagnosis and repair — 12 questions (30%)
- Suspension systems diagnosis and repair — 12 questions (30%)
- Wheel alignment diagnosis, adjustment and repair — 11 questions (28%)
- Wheel and tire diagnosis and service — 5 questions (12%)
There is no section you can safely ignore. Alignment theory is 28 percent of the test and it is the section technicians most often assume they will absorb by osmosis from the alignment rack. You will not. The angles have to be learned deliberately.
Alignment: learn the angles cold
Know camber, caster and toe — what each one is, what each one does to tire wear, and what each one does to how the vehicle drives. Then know the direction of each effect, because that is what the questions test.
- Camber — tilt of the wheel viewed from the front. Excessive negative camber wears the inside edge. Unequal camber side to side pulls toward the more positive side.
- Caster — tilt of the steering axis viewed from the side. Positive caster gives straight-line stability and return-to-center. Unequal caster pulls toward the less positive side. Caster does not cause tire wear.
- Toe — the biggest tire killer of the three. Feathered wear across the tread is a toe problem. Toe out on turns relates to the steering geometry, not to static toe.
Also know the diagnostic angles: SAI, included angle, thrust angle and setback. A vehicle with correct camber but an SAI that differs side to side has bent structure, and the test will describe exactly that scenario and ask what you conclude. Thrust angle explains a crooked steering wheel after a front-only alignment.
Steering: the 30 percent
Cover rack and pinion and recirculating ball, power steering hydraulics, and electric power steering. Know how to diagnose morning sickness in an older pump, what causes a whine that changes with steering input, and why fluid level and aeration produce different noises.
Know the inspection procedures cold, because the test cares about method: how you check a ball joint depends on whether it is loaded or unloaded, and checking a loaded joint with the suspension hanging tells you nothing. Same idea with tie rod ends and idler arms — specified play, measured the specified way. Steering column, intermediate shaft and clockspring questions show up in the smaller print.
Suspension: the other 30 percent
Struts, shocks, springs, control arms, bushings, sway bars and their links. Know the failure symptoms: a worn strut mount that binds and clunks on turns, a collapsed spring that changes ride height and therefore alignment, a sway bar bushing that rattles over small bumps but is silent on big ones.
Understand the relationship between ride height and alignment, because it appears repeatedly — a sagging spring changes camber and toe, so measuring ride height comes before adjusting angles. Electronic and air suspension basics are worth an hour: service mode, height sensors and why you disable a system before lifting some vehicles.
Wheels and tires: the 12 percent
Five questions, and they overlap heavily with work you already do. Radial and lateral runout, static versus dynamic balance, tire wear patterns, load index and speed rating, and TPMS relearn procedures. Our TPMS troubleshooting guide and what every technician should know about tires cover most of it.
Test-taking tips specific to A4
Draw the angle. If a question describes a camber or caster condition, sketch it on your scratch paper. Two seconds of drawing prevents the most common A4 error, which is getting the direction of a pull backwards.
Pull direction is a favourite. Camber pulls toward the more positive side, caster pulls toward the less positive side. Memorise those two sentences. You will use them.
Watch for the loaded-versus-unloaded trap. Inspection questions frequently hinge on whether the suspension is supporting the vehicle weight. Read the setup described before you evaluate the answer.
Technician A / Technician B: judge each one separately. Decide true or false for A, then for B, then answer. On A4 the wrong technician is usually right about the component and wrong about the procedure.
Answer to spec, not to habit. If your shop sets toe at the low end of the range as a matter of routine, the test does not care. The answer is the published procedure.
There is more general strategy in how to pass your ASE test the first time.
Booking it
The registration fee is charged once per order rather than per test, so pair A4 with A5 or G1 and take them in one booking. The current cost and registration windows are in what ASE certification costs and how to register.
A4 is one of the eight tests required for Master Automobile Technician status and is valid for five years.
The full A-series runs A1 through A9. Study guides for the others: A1 engine repair, A2 automatic transmission, A3 manual drive train, A5 brakes, A6 electrical, A7 heating and air conditioning, A8 engine performance and A9 light vehicle diesel.
Related reading
- Working on Rust Belt Cars: What Michigan Winters Do to a Repair
- Your First Tool Box: What a New Technician Actually Needs
- From Lube Tech to Master Tech: The Actual Career Path
Work somewhere that pays for this
Arnaz Group pays for every ASE test you pass, and certification moves your pay. Alignment and suspension work is steady across all ten of our Midas locations. See our open roles in Wayne, Oakland and Washtenaw counties.