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 - Tests W/Codes: Introduction
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with self-diagnostics. If no fault codes, or only pass codes, are displayed after entering self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
This article uses many abbreviations for devices, signal names, and wire colors. See SELF-DIAGNOSTICS ABBREVIATIONS table. Abbreviations for wire colors in individual PINPOINT TEST diagrams are as follows:
- BLK - Black
- BLU - Blue
- BRN - Brown
- GRN - Green
- LT GRN - Light Green
- ORG - Orange
- PNK - Pink
- RED - Red
- WHT - White
- YEL - Yellow
| Application | Abbreviation |
|---|---|
| A/C Relay | ACR |
| Analog Volt-Ohmmeter | VOM |
| Barometric Pressure Sensor | BARO |
| Blower Motor Control | BLMT |
| Boost Pressure Switch | BPS |
| Brake ON/OFF Switch | BOO |
| Breakout Box | BOB |
| Canister Purge Control Solenoid | CANP |
| Clutch Cycling Pressure | CCPS |
| Clutch Pedal Position | CPP |
| Condenser Fan Relay | CFAN |
| Crankshaft Position Sensor | CKP |
| Cylinder Identification Sensor | CID |
| Data Link Connector | DLC |
| Defroster Switch | DEF |
| Digital Volt-Ohmmeter | DVOM |
| Electric Load Control Unit | ELU |
| Engine Coolant Temperature Sensor | ECT |
| Fuel Pressure Regulator Control Solenoid | FPRC |
| Fuel Pump Relay | FPR |
| Headlight Switch | HDLP |
| High Pressure Switch | HPS |
| Idle | IDL |
| Idle Speed Control | ISC |
| Ignition Diagnostic Monitor | IDM |
| Ignition Switch | VST |
| Intake Air Temperature Sensor | IAT |
| Keep Alive Power | KAPWR |
| Key On Engine Off | KOEO |
| Key On Engine Running | KOER |
| Knock Control | KC |
| Malfunction Indicator Light | MIL |
| Mass Airflow Meter | MAF |
| New Generation Star Scan Tester | NGS |
| Oxygen Sensor | O2S |
| Park/Neutral Position | PNP |
| Power & Ground Connections | PGC |
| Power Steering Switch | PSP |
| Powertrain Control Module | PCM |
| Relay Output Check | ROC |
| Reference Voltage & Signal Return | VREF |
| Self-Test Input | STI |
| Self-Test Output | STO |
| Signal Return | SIGRTN |
| Solenoid Controlled By Ground | SCG |
| Switch Monitor Lamp | SML |
| Switch To Ground | STG |
| Switch To Power | STP |
| Throttle Position Sensor | TP |
| Transmission Control Module | TCM |
| Volume Airflow Meter | VAF |
| Vehicle Power | VPWR |
| Vehicle Speed Sensor | VSS |
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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