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 present after entering self-diagnostics, proceed to TESTS W/O CODES article in this 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 ABBREVIATIONS table in TESTS W/CODES article in this section. Abbreviations for wire colors used 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 |
|---|---|
| Analog Volt-Ohmmeter | VOM |
| Barometric Pressure Sensor | BARO |
| Breakout Box | BOB |
| Canister Purge Control Solenoid | CANP |
| Malfunction Indicator Light | MIL |
| Crankshaft Position Sensor | CPS |
| Cylinder Identification Sensor | CID |
| Electric Load Control Unit | ELU |
| Engine Coolant Temperature Sensor | ECT |
| Fuel Pressure Regulator Control Solenoid | FPRC |
| Idle Speed Control | ISC |
| Ignition Diagnostic Monitor | IDM |
| Keep Alive Power | KAPWR |
| Key On Engine Off | KOEO |
| Key On Engine Running | KOER |
| Knock Control | KC |
| Oxygen Sensor | O2S |
| Power & Ground Connections | PGC |
| 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 |
| Vane Airflow Meter | VAF |
| Vane Air Temperature Sensor | VAT |
| 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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