LS1 · 2002 · BEFORE DIAGNOSIS
2002 LS1 Diagnostic Preliminary Checks
2002 LS1 pre-diagnostic checklist for DTCs, scan data, overheating fuel-disable behavior, VTD start/stall and aftermarket electrical changes.
APPLICATION: 2002 Firebird / Formula / Trans Am 5.7L LS1.
BEFORE THE SYMPTOM TREE
Do the system check first.
GM requires the diagnostic system check and basic scan-data review before symptom diagnosis. Save evidence before clearing codes or disconnecting power.
OVERHEAT TRAP
Extreme coolant temperature can intentionally create a miss/lack of power.
At coolant temperature above 270°F (132°C), the PCM can enter an over-temperature fuel-disabled mode that turns fuel off to four cylinders at a time. The driver can perceive this as lack of power, misfire or rough idle.
WORKFLOW
- Verify module communication and MIL operation; save stored/pending/history DTCs and failure data.
- Confirm the customer complaint before choosing a symptom path.
- Review scan data for implausible inputs instead of assuming the named symptom is one component.
- For start-and-stall, check VTD-related DTCs/security behavior.
- Inspect recent repairs and aftermarket electrical options that may have altered the system.
- If the condition is intermittent, reproduce the failure conditions rather than replacing parts after it disappears.
FPV RULE
Evidence first.
A code, PID or symptom narrows the search. A failed test authorizes the repair. After repair, recreate the original complaint conditions safely.