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 the TESTS W/O CODES article 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 |
NO RELATED
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.