How To Use Circuit Tests
1) Ensure all non-EEC-IV related faults found while performing steps in BASIC TESTING article have been corrected. DO NOT perform any CIRCUIT TEST unless instructed by a QUICK TEST procedure. Follow each test step in order until fault is found. When more than one code is retrieved, start with first code displayed.
2) CIRCUIT TESTS ensure electrical circuits are okay before sensors or other components are replaced. Always test circuits for continuity between sensor and ECA. Test all circuits for short to power, opens or short to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with ignition on unless otherwise specified in CIRCUIT TESTS.
3) DO NOT measure voltage or resistance at PCM. DO NOT connect any test light unless specified in testing procedure. Make all measurements by probing rear of connector. Isolate both ends of circuit and turn ignition off when checking continuity, unless instructed otherwise.
4) Disconnect solenoids and switches from harness before measuring continuity and resistance or applying voltage. After each repair, check all component connections and repeat QUICK TEST.
| Circuit Test Title | Circuit Tested | |
|---|---|---|
| No-Start & Voltage Tests | ||
| AC | No Start (EI) | |
| B | Checking Vehicle Battery | |
| C | Reference Voltage | |
| Input Sensor Tests | ||
| DA | Temperature Sensor Test (ECT & IAT) | |
| DC | MASS Airflow (MAF) Sensor | |
| DH | Throttle Position (TP) Sensor | |
| DL | Differential Pressure Feedback EGR (DPFE) | |
| DP | Vehicle Speed Sensor (VSS) | |
| DR | Cylinder Identification (CID) System | |
| Additional Input Component Tests | ||
| FD | Brake On-Off (BOO) Switch | |
| Fuel Control System Tests | ||
| G | MAF/TP/Fuel Injector Pulse Width Test | |
| H | Fuel Control | |
| HA | Adaptive Fuel | |
| J | Fuel Pump Circuit (Relay & Inertia Fuel) | |
| PCM (Processor) Output Tests | ||
| KD | Canister Purge (CANP) | |
| KE | Idle Air Control (IAC) Solenoid | |
| KM | Wide Open Throttle A/C Cut-Out (WAC) | |
| KP | Octane Adjust | |
| M | Dynamic Response Test | |
| ML | Self-Test Output (STO) Or Malfunction | |
| N | Ignition Diagnostic Monitor (IDM) | |
| P | Spark Timing Check | |
| QA | No Codes/Codes Not Listed | |
| QB | Continuous Memory Service Code 15 Or 512 | |
| QC | Output State Check Not Functioning | |
| S | System Check | |
| TA | Clutch Pedal Position (CPP) Switch | |
| TB | Transmission Solenoids A4LD | |