Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Test 1A - Trouble Codes
Battery must be fully charged before proceeding. Use this diagnostic information only when instructed to by another diagnostic article. Display will fit 2 categories: scan tool failure message or BUS failure message. Connect scan tool to Data Link Connector (DLC) to read message. See TROUBLE CODES table and proceed to appropriate test. If scan tool screen is blank, go to TEST 2A.
| Message | Test No. | |
|---|---|---|
| BUS Failure Message | ||
| SHORT TO BATTERY | 7A | |
| SHORT TO 5 VOLTS | 8A | |
| SHORT TO GROUND | 9A | |
| BUS + & BUS - SHORTED TOGETHER | 10A | |
| NO TERMINATION | 11A | |
| BUS BIAS LEVEL TOO LOW | 12A | |
| BUS BIAS LEVEL TOO HIGH | 12A | |
| BUS + OPEN | 12A | |
| BUS - OPEN | 12A | |
| BUS + & BUS - OPEN | 12A | |
| NO BUS BIAS | 13A | |
| NOT RECEIVING BUS MESSAGES CORRECTLY | 14A | |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.