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.
Engine Controls - System/Component Tests - 3.1L: Introduction
Before testing separate components or systems, perform all procedures listed in BASIC TESTING article in this section. Since many computer-controlled and monitored components will set a diagnostic trouble code if they malfunction, it is also recommended that self-diagnosis be performed. Refer to TESTS W/CODES - 3.1L article in this section.
| System or Component | Diagnostic Information Location | ||||
|---|---|---|---|---|---|
| A-1 & A-2, Malfunction Indicator Light (MIL) | (1) See DIAGNOSTIC CIRCUIT CHECK | ||||
| A-3, No Start | (1) See NO START - ENGINE CRANKS OKAY | ||||
| A-5, Fuel Pump Relay | See RELAYS, SOLENOIDS & MOTORS | ||||
| A-7, Fuel System Diagnosis | (1) See BASIC FUEL SYSTEM CHECKS | ||||
| C-1, ECM/PCM Replacement Check | See ECM/PCM REPLACEMENT CHECK | ||||
| C-1, MAP Sensor | See ENGINE SENSORS & SWITCHES | ||||
| C-1, Power Steering Pressure Switch | See ENGINE SENSORS & SWITCHES | ||||
| C-1, Park/Neutral Switch | See ENGINE SENSORS & SWITCHES | ||||
| C-2, Injector Balance Test | See FUEL SYSTEM | ||||
| C-2, IAC Motor | See IDLE CONTROL SYSTEM in | ||||
| C-2, ISC Motor | See IDLE CONTROL SYSTEM in | ||||
| C-3, Canister Purge System (Fuel Evaporation Control) | See EMISSION SYSTEMS & SUB-SYSTEMS | ||||
| C-4, EST Ignition Check | (1) See BASIC IGNITION SYSTEM CHECKS | ||||
| C-5, ESC Ignition Check | See IGNITION SYSTEM | ||||
| C-6, Air Injection System | See EMISSION SYSTEMS & SUB-SYSTEMS | ||||
| C-7, EGR System | See EMISSION SYSTEMS & SUB-SYSTEMS | ||||
| C-8, Torque Converter Clutch (Trans.) | See MISCELLANEOUS ECM CONTROLS | ||||
| C-8, M/T Shift Lights (Trans.) | See MISCELLANEOUS ECM CONTROLS | ||||
| C-10, A/C Clutch Control (2) | See MISCELLANEOUS ECM CONTROLS | ||||
| C-12, Electric Cooling Fan Control (2) | See MISCELLANEOUS ECM CONTROLS | ||||
| C-18, Supercharger Boost Control | See AIR INDUCTION SYSTEMS | ||||
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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.