ASE T6 Electrical practice test
The T6 test applies A6-style circuit reasoning to trucks: multiple batteries in parallel, heavy cranking circuits, trailer and lighting circuits, and the J1939 data bus that ties truck modules together. Required for Master Truck status.
Technician A says welding on a truck chassis calls for disconnecting battery ground (and following OEM electronics protection steps) to protect modules. Technician B says when removing battery cables, the ground cable is disconnected first and reconnected last. Who is correct?
How the T6 test works
50 scored questions
+ ~10 unscored research questions
90 minutes
computer-based, at a test center
$62 per test
plus one $34 registration fee per order
Valid 5 years
then a shorter recertification test
ASE does not publish a fixed passing percentage — scores are scaled. Around 65–70% correct is the commonly cited range; aim above 80% in practice so you walk in with margin. The certificate is issued once ASE verifies your required work experience.
What the T6 test covers
The official task list for T6 Electrical/Electronic Systems (Medium-Heavy Truck) breaks down into these content areas — the practice bank above draws from all of them:
- General electrical diagnosis — Ohm’s law, voltage drop, meter use
- Batteries — parallel banks, testing, parasitic draw
- Starting and charging systems at heavy-duty current levels
- Lighting and trailer circuits — seven-way connector, grounds
- Instrumentation, driver information, and body electrical
- Data bus and module communication — J1939/CAN basics
Frequently asked
- How many questions are on the ASE T6 test?
- The T6 test has 50 scored questions plus about 10 unscored research questions, with a 90-minute time limit.
- How do truck batteries differ from a car setup?
- Most trucks run multiple 12-volt batteries in parallel: voltage stays 12 V while capacity and cranking amps add. One weak battery drags the whole bank down, so they are tested and usually replaced as a matched set.
- What is J1939?
- The standard heavy-duty CAN data bus that lets the engine, transmission, ABS, and body modules share data. Bus-level diagnosis (termination resistance, backbone shorts) is on the task list.
Other ASE practice tests
Driving trucks, not just wrenching on them?
HaulSchool has free CDL practice tests — general knowledge, air brakes, and every endorsement — plus plain-English DOT physical guides.
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