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Honda Prelude 4WS 1994 - 1994 ENGINE PERFORMANCE Self-Diagnostics
Honda Prelude 4WS 1994 - INTRODUCTION
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with self-diagnostics. If no Diagnostic Trouble Codes (DTCs) or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
Honda Prelude 4WS 1994 - SELF-DIAGNOSTIC SYSTEM Hard Failures
Hard failures cause Malfunction Indicator Light (MIL) to illuminate and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined by retrieving DTCs and using TROUBLE CODE CHARTS. See RETRIEVING CODES . If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.
Honda Prelude 4WS 1994 - Intermittent Failures
Intermittent failures may cause Malfunction Indicator light (MIL) to flicker or illuminate and go out after the intermittent fault goes away. The corresponding DTC will be retained in ECM memory. If related fault does not reoccur within 50 starter operations, related DTC will be erased from control unit memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.
Honda Prelude 4WS 1994 - MALFUNCTION INDICATOR LIGHT (MIL)
All models are equipped with an MIL. As a bulb check, light illuminates when ignition is on and engine is not running. MIL also illuminates when a system failure has been detected and a corresponding DTC has been set in ECM memory. Not all trouble codes will activate MIL. If MIL is on and no DTCs are in memory, problem may be intermittent. See INTERMITTENTS in TESTS W/O CODES article.
Honda Prelude 4WS 1994 - RETRIEVING CODES
Turn ignition off. Insert jumper wire in service check connector, located behind center console. See Fig. 1 .
Turn ignition on. Diagnostic Trouble Codes (DTCs) will be indicated by a series of long and short flashes on MIL. The number of long flashes indicates the number in the 10s column. The number of short flashes indicates the number in the 1s column. For example, 4 long flashes followed by 3 short flashes would indicate DTC 43.
See DIAGNOSTIC TROUBLE CODE IDENTIFICATION TABLE and proceed to appropriate TROUBLE CODE CHART for testing. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedure.
Fig. 1: Honda Prelude 4WS 1994 - Component Locations - Locating Service Check Connector
Honda Prelude 4WS 1994 - DIAGNOSTIC TROUBLE CODE DEFINITION
Honda Prelude 4WS 1994 DIAGNOSTIC TROUBLE CODE IDENTIFICATION
Code (1) System Affected Probable Cause 0 ECM No Signal To ECM 1 Heated Oxygen Sensor (HO2S) Problem In HO2S Circuit 3 MAP Sensor Electrical Problem In MAP Sensor 4 Crank Angle Sensor (CKP) Open Or Shorted Signal Circuit 5 MAP Sensor Electrical problem in MAP Sensor 6 Engine Coolant Temperature (ECT) Sensor Open Or Shorted Signal Circuit 7 Throttle Position (TP) Sensor Open Or Shorted Signal Circuit 8 Crank Angle Sensor (TDC) Open Or Shorted Signal Circuit 9 Crank Angle Sensor (CYP) Open Or Shorted Signal Circuit 10 Intake Air Temperature(IAT) Problem With Sensor 12 EGR System No EGR Action 13 Barometric Pressure (BARO) Sensor Problem With PA Circuit 14 Idle Air Control(IAC) Valve Open Or Shorted Signal Circuit 15 Ignition Output Signal Electrical Problem In Signal Circuit 16 Fuel Injector Problem In Fuel Injector Circuit 17 Vehicle Speed Sensor (VSS) Open Or Shorted Signal Circuit 20 (2) Electrical Load Detector (ELD) Problem With ELD Circuit 21 Spool Solenoid Valve Problem With VTEC Spool Solenoid Circuit 2222 VTEC Oil Pressure Switch Problem In VTEC Oil Pressure Switch Circuit 23 Knock Sensor (KS) Knock Sensor Circuit Fault 30 A/T FI Signal A Problem In A/T Control Unit And ECM Circuit 31 A/T FI Signal B Problem In A/T Control Unit And ECM Circuit 41 Heated Oxygen Sensor (HO2S) Heater Problem With HO2S Circuit 43 Fuel Supply System Problem With HO2S Circuit Or Fuel System
If codes other than these are indicated, repeat self-diagnosis. If code(s) reappear, substitute a known good ECM, and recheck codes. If code(s) clear, replace ECM. (1)
MIL does not come on when there is a malfunction in ELD circuit, but code is stored in ECM memory. (2)
Honda Prelude 4WS 1994 - ECM RESET PROCEDURE/CLEARING CODES
NOTE: Some models have an anti-theft code built into the radio circuit. Clearing codes cancels clock and radio settings; make note of settings before beginning reset procedure. After ECM reset, the radio will not function until code is entered.
To reset ECM (clear codes), remove CLOCK/RADIO fuse from underhood fuse/relay block. Leave fuse out for 10 seconds to reset ECM.
Honda Prelude 4WS 1994 - ECM LOCATION
On Prelude, ECM is located under carpet in passenger-side footwell.
Honda Prelude 4WS 1994 - TEST EQUIPMENT
All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedure.
On Accord and Prelude, when directed by testing to install Engine Control Module (ECM) test harness, turn ignition off. Connect ECM Test Harness (07LAJ-PT3010A) between ECM and ECM connector. See Fig. 2 . Follow testing directions. For test harness terminal identification, see Fig. 5 . For oil pressure gauge hookup, see Fig. 4 .
On Odyssey, use Backprobe Set (07SAZ-001000A) to backprobe Engine Control Module (ECM) when directed by testing. See Fig. 3 . For ECM connector terminal identification, see Fig. 5 .
Fig. 3: Honda Prelude 4WS 1994 - Component Locations - Using Backprobe Set (Odyssey)
Honda Prelude 4WS 1994 - DIAGNOSTIC TROUBLE CODE CHARTS
NOTE: In the following diagnostic trouble code charts, illustrations and schematics are courtesy of American Honda Motor Co., Inc.
Honda Prelude 4WS 1994 - Using Diagnostic Trouble Code Charts
To use DIAGNOSTIC TROUBLE CODE CHARTS, see RETRIEVING CODES under SELF-DIAGNOSTIC SYSTEM. After codes have been recorded, proceed to appropriate DIAGNOSTIC TROUBLE CODE CHART.
When directed by chart to install ECM test harness, turn ignition off. Connect ECM Test Harness (07LAJ-PT3010A ) between ECM and connector. See Fig. 5 . Follow code chart directions.
NOTE: The Following Flow Charts are Courtesy of American Honda Motors Co., Inc.
Honda Prelude 4WS 1994 - CODE/NO CODE - NO START TROUBLE SHOOTING
Honda Prelude 4WS 1994 - CODE 1 - HEATED OXYGEN SENSOR (HO2S)
Honda Prelude 4WS 1994 - CODE 3 - MAP SENSOR CIRCUIT
Honda Prelude 4WS 1994 - CODE 4, 8 AND/OR 9 - TDC/CKP/CYP SENSOR
Honda Prelude 4WS 1994 - CODE 5 - MAP SENSOR CIRCUIT
Honda Prelude 4WS 1994 - CODE 6 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR
Honda Prelude 4WS 1994 - CODE 7 - THROTTLE POSITION (TP) SENSOR
Honda Prelude 4WS 1994 - CODE 10 - INTAKE AIR TEMPERATURE (IAT) SENSOR
Honda Prelude 4WS 1994 - CODE 12 - EGR SYSTEM
Fig. 25: Honda Prelude 4WS 1994 - Component Locations - Code 12 Flow Chart (1 Of 5) EGR System
Fig. 26: Honda Prelude 4WS 1994 - Component Locations - Code 12 Flow Chart (2 Of 5) EGR System
Fig. 27: Honda Prelude 4WS 1994 - Component Locations - Code 12 Flow Chart (3 Of 5) EGR System
Fig. 28: Honda Prelude 4WS 1994 - Component Locations - Code 12 Flow Chart (4 Of 5) EGR System
Fig. 29: Honda Prelude 4WS 1994 - Component Locations - Code 12 Flow Chart (5 Of 5) EGR System
Honda Prelude 4WS 1994 - CODE 13 - BAROMETRIC PRESSURE (BARO) SENSOR
Honda Prelude 4WS 1994 - CODE 14 - IDLE AIR CONTROL (IAC) VALVE
Honda Prelude 4WS 1994 - CODE 15 - IGNITION OUTPUT SIGNAL
Honda Prelude 4WS 1994 - CODE 16 - FUEL INJECTORS
Fig. 35: Honda Prelude 4WS 1994 - Component Locations - Code 16 Flow Chart (1 Of 3) Fuel Injectors
Fig. 36: Honda Prelude 4WS 1994 - Component Locations - Code 16 Flow Chart (2 Of 3) Fuel Injectors
Fig. 37: Honda Prelude 4WS 1994 - Component Locations - Code 16 Flow Chart (3 Of 3) Fuel Injectors
Honda Prelude 4WS 1994 - CODE 17 - VEHICLE SPEED SENSOR (VSS)
Honda Prelude 4WS 1994 - CODE 20 - ELECTRICAL LOAD DETECTOR (ELD)
Honda Prelude 4WS 1994 - CODE 21 - VTEC SOLENOID VALVE CIRCUIT
Honda Prelude 4WS 1994 - CODE 22 - VTEC PRESSURE SWITCH CIRCUIT
Honda Prelude 4WS 1994 - CODE 23 - KNOCK SENSOR (KS)
Honda Prelude 4WS 1994 - CODE 30 OR 31 - A/T FI SIGNAL "A" (30) OR "B" (31)
Honda Prelude 4WS 1994 - CODE 41 - HEATED OXYGEN SENSOR (HO2S) HEATER
Honda Prelude 4WS 1994 - CODE 43 - FUEL SUPPLY SYSTEM
Honda Prelude 4WS 1994 - SUMMARY
If no hard trouble codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedure.