How To Use Circuit Tests

1)  Ensure all non-EEC-IV related faults found while performing steps in BASIC TESTING article in the ENGINE PERFORMANCE section have been corrected. 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 replacing sensors or other components. Always test continuity of circuits between sensor and PCM. 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. All measurements are made by probing rear of connector. Isolate both ends of a circuit and turn ignition off when checking continuity.

4)  Disconnect solenoids and switches from harness before measuring continuity and resistance or applying voltage. After each repair, reconnect all component connections and repeat QUICK TEST.

5)  An open circuit is defined as a resistance reading of greater than 5 ohms. This specification tolerance may be too high for some items in EEC-IV system. If resistance approaches 5 ohms, always clean suspect connector and coat it with protective dielectric silicone grease. A short is defined as a resistance reading of less than 10,000 ohms to ground, unless stated otherwise in CIRCUIT TEST.

CIRCUIT TESTS are grouped as follows.

• A-C - No Start & Voltage Tests
• DA-DS - Input Sensor Tests
• FD-FF - Additional Input Component Tests
• G-J - Fuel Control System Tests
• KA-TC - PCM Output Tests
  CIRCUIT TEST INDEX
  
  

  Application/Circuit Test		Test Definition
  No-Start & Voltage Tests
  AA		No Start (3.0L)
  AB		No Start (2.3L)
  B		Checking Vehicle Battery
  C C		Reference Voltage
  Input Sensor Tests
  DA		Temperature Sensor Test IAT/ECT
  DC		MASS Airflow (MAF) Sensor
  DG		Knock Sensor (KS)
  DH		Throttle Position (TP) Sensor
  DL		DPFE Sensor & EVR Solenoid
  DN		EVP Sensor & EVR Solenoid
  DP		Vehicle Speed Sensor (VSS)
  DR		Cylinder Identification (CID) Circuit
  Additional Input Component Tests
  FD		Brake On-Off (BOO) Switch
  FF		Power Steering Pressure (PSP) Switch
  Fuel Control System Tests
  G		MAF/TP Sensor Fuel Injector Pulse Width Test
  H		Fuel Control
  HA		Adaptive Fuel
  J		Fuel Pump Circuit (Relay & Inertia Switch)
  PCM (Processor) Output Tests
  KA		EGR Vacuum Regulator (EVR) Solenoid
  KB		Canister Purge (CANP) Valve
  KD		Canister Purge (CANP) Solenoid
  KE		Idle Air Control (IAC) Solenoid
  KM		WAC & A/C Demand Switch
  KP		Octane Adjust
  M		Dynamic Response Test
  ML		Self-Test Output Or MIL
  NA		Ignition Diagnostic Monitor (IDM) (3.0L)
  NB		Ignition Diagnostic Monitor (IDM) (2.3L)
  PA		Spark Timing Check (3.0L)
  PB		Spark Timing Check (2.3L)
  QA		No Codes/Codes Not Listed
  QB		Continuous Memory Code 512
  QC		Output State Check Not Functioning
  S		System Check
  TA		CPP Switch/PNP Switch
  TC		Transmission Solenoids