Engine Controls - System/component Tests - Efi Honda Prelude III рестайлинг

INTRODUCTION

Before testing separate components or systems, perform procedures in BASIC TESTING article. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES article.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Testing individual components does not isolate shorts or opens. Use ohmmeter to isolate wiring harness shorts or opens.

AIR INTAKE SYSTEM

Note. DO NOT adjust by-pass valve full-close screw. Adjustment is preset at the factory.

Scheme 28

1. Check by-pass valve shaft for binding or sticking. Check by-pass valve for smooth movement. Ensure tab on by-pass valve is in close contact with stopper when by-pass valve is fully open. (Scheme 28)
2. Check that tab of by-pass valve is in close contact with full-close screw when valve is fully closed. (Scheme 28) If any fault is found, clean linkage and shafts with carburetor cleaner.
3. If problem still exists after cleaning, disassemble intake manifold and check by-pass valve.

Scheme 29

Scheme 30

1. Start engine and allow to idle. Remove vacuum hose No. 13 from by-pass control diaphragm and connect vacuum gauge to hose. (Scheme 29) If vacuum is present, go to next step. If vacuum is not present, remove vacuum hose No. 12 from vacuum tank and check for vacuum. (Scheme 29) If vacuum is present, go to step 3). If not, repair blockage or leak between vacuum tank and intake manifold and recheck.
2. Raise engine speed to 5000 RPM and check for vacuum at hose No. 13. (Scheme 29) If vacuum is not present, solenoid is okay. If vacuum is present, disconnect 4-wire connector at control box and check for vacuum again. If vacuum is still present, replace solenoid valve. If vacuum is no longer present, solenoid valve is okay.
3. Disconnect 4-wire connector at control box. Measure voltage between Black/Yellow (positive) wire terminal and Yellow (negative) wire terminal. (Scheme 30) If battery voltage is present, replace by-pass control solenoid valve. If battery voltage is not present, check continuity of wiring to solenoid valve.

Intake Control Diaphragm (Accord)

Connect a vacuum pump to vacuum hose on intake control diaphragm. Apply vacuum. If diaphragm holds vacuum, intake diaphragm is okay. If vacuum is not held, check vacuum line for proper connection or disconnected hose. If hose is okay, replace intake control diaphragm.

Intake Control Solenoid Valve (Accord)

1. Start engine and allow to idle. Remove upper vacuum hose from intake control solenoid valve and connect a vacuum gauge to solenoid valve. If vacuum is not present, go to step 2). If vacuum is present, raise engine speed to 3700 RPM. If vacuum is still present, go to step 4). If vacuum is no longer present, solenoid valve is okay.
2. Disconnect lower vacuum hose of solenoid valve from air chamber and connect a vacuum gauge. If vacuum is present, go to next step. If vacuum is not present, check vacuum line for proper connection, cracks or blockage in hose. If vacuum line is okay, clean manifold port.
3. Disconnect 2-wire connector from intake control solenoid valve. Measure voltage between Black/Yellow (positive) terminal and White (negative) terminal. If battery voltage is not present, solenoid valve is okay. If battery voltage is present, replace intake control solenoid valve.
4. Disconnect 2-wire connector from solenoid valve. Check vacuum gauge. If vacuum is no longer present, solenoid valve is okay. If vacuum is still present, replace solenoid valve.

Scheme 31

1. Check tandem valve shaft for binding or sticking. Check tandem by-pass valve for smooth movement. (Scheme 31) If any fault is found, clean linkage and shafts with carburetor cleaner.
2. Disconnect vacuum hose from tandem valve control diaphragm and connect vacuum pump to diaphragm. Apply vacuum and check that tandem valve lever moves and that lever is in close contact with stopper when tandem valve is fully open. If any fault is found, replace tandem valve control diaphragm.

Scheme 32

1. Disconnect vacuum hose from tandem valve control diaphragm. Connect vacuum gauge to hose. Start engine and let idle. Ensure engine coolant temperature is less than 160°F (71°C).
2. If vacuum is not present, go to step 3). If vacuum is present, disconnect 2-wire connector from tandem valve control solenoid and recheck vacuum gauge. (Scheme 32) If vacuum is still present, replace tandem valve control solenoid valve. If vacuum is no longer present, solenoid valve is okay.
3. Raise engine speed to 3000 RPM for M/T and to 2000 for A/T. If vacuum is present, solenoid valve is okay. If vacuum is not present, disconnect 2-wire connector from tandem valve control solenoid valve. Measure voltage between Black/Yellow (positive) wire terminal and Orange (negative) wire terminal with engine speed at 3000 RPM (2000 RPM for A/T). (Scheme 32)
4. If battery voltage is not present, solenoid valve is okay. If battery voltage is present, remove solenoid valve from throttle body and check port for blockage. If port is okay, replace solenoid valve.

Ground Circuits

1. Using an ohmmeter, check for continuity to ground on appropriate ECU ground terminals. (Scheme 35)and (Scheme 36). Also, refer to the «POWER & GROUND TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. Resistance should be zero ohms for each circuit. If reading is not zero ohms, repair open to ground.
2. Using a DVOM, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than.1 volt. If voltmeter reading is greater than.1 volt, check for open, corrosion or loose connection on ground lead.

Power Circuits

1. Using a voltmeter, check for battery voltage between ECU power terminal and ground. See «POWER & GROUND TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If battery voltage is not present, check appropriate ECU fuse in underhood fuse box. See «ECU POWER CIRCUITS FUSE IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. If fuse is okay, check for an open in wire between underhood fuse box and appropriate ECU power circuit terminal.
2. Turn ignition switch to ON position. Using a voltmeter, check for battery voltage between appropriate ECU power circuit terminal and ground. See «POWER & GROUND TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If battery voltage is not present, check appropriate fuse in underhood fuse box. See «ECU POWER CIRCUITS FUSE IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. If fuse is okay, check for an open in wire between fuse box and appropriate ECU power circuit terminal, or check for a defective ignition switch. POWER & GROUND TERMINAL IDENTIFICATION Application (1) ECU Terminal Accord Ground Circuits A23, A24, A26 & B2 Power Circuits Ignition Switch In OFF Position D1 Ignition Switch In ON Position A25 & B1 Civic & CRX Ground Circuits A2, A4, A16 & A18 Power Circuits Ignition Switch In OFF Position B1 Ignition Switch In ON Position A13 & A15 Prelude 2.0L Ground Circuits A2, A4, A16 & A18 Power Circuits Ignition Switch In OFF Position A17 Ignition Switch In ON Position A13 & A15 2.1L Ground Circuits A23, A24, A26 & B2 Power Circuits Ignition Switch In OFF Position D1 Ignition Switch In ON Position A25 & B1 (1) (Scheme 35)and (Scheme 36) for terminal location identification. ECU POWER CIRCUITS FUSE IDENTIFICATION Application (1) Fuse Accord Ignition Switch In OFF Position Back-Up Ignition Switch In ON Position ECU Civic & CRX Ignition Switch In OFF Position Hazard Ignition Switch In ON Position ECU Prelude Ignition Switch In OFF Position Clock Ignition Switch In ON Position EFI/ECU (1) All fuses in underhood fuse box.

ENGINE SENSORS & SWITCHES

Note. Some test procedures require the use of a test harness when testing certain components or systems. Accord and Prelude 2.1L models use ECU Test Harness (07LAJ-PT3010A ). (Scheme 33) Civic, CRX and Prelude 2.0L models use PGM-FI Test Harness (07999-PD6000A ). (Scheme 34) Test harness must be connected between control unit and main wire harness connectors.

Scheme 33

Scheme 34

Scheme 35

Scheme 36

Accord & Prelude 2.1L

PA sensor is built into ECU. See TESTS W/CODES article for testing.

Civic, CRX & Prelude 2.0L

Connect appropriate test harness between ECU and wiring harness connectors. (Scheme 34) Turn ignition switch to ON position. Measure voltage between test harness terminals C9 (positive) and C12 (negative). (Scheme 36) If voltage is approximately 3.0 volts, PA sensor is okay. If voltage is not within specification, check wiring. If wiring is okay, replace sensor.

Resistance Test

Start engine and warm to normal operating temperature. Disconnect sensor connector. Using an ohmmeter, measure resistance across sensor terminals. If resistance is not 200-400 ohms, replace sensor.

Disconnect 2-wire connector from CYL sensor. Measure resistance between CYL sensor terminals. If resistance is not 700-1100 ohms, replace CYL sensor assembly. If resistance is within specifications, check continuity to ground on each of the 2 sensor terminals individually. If continuity exists, replace CYL sensor assembly.

Functional Test

See EMISSION SYSTEMS & SUB-SYSTEMS in this article.

Disconnect sensor connector. Using an ohmmeter, measure resistance across sensor terminals. Resistance should be as specified. If not within specification, replace sensor. See INTAKE AIR TEMPERATURE (TA) SENSOR RESISTANCE TEST table.

INTAKE AIR TEMPERATURE (TA) SENSOR RESISTANCE TEST

Voltage Test

1. Connect appropriate test harness between ECU and main wire harness connectors. (Scheme 33)and (Scheme 34). Turn ignition switch to the "ON" position. Measure voltage between the appropriate terminals. Refer to the «MAP SENSOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36).
2. If voltage is approximately 3 volts, go to next step. If voltage is not approximately 3 volts, check wiring to sensor for continuity. If wiring is okay, replace MAP sensor.
3. Connect a vacuum pump to MAP sensor and apply vacuum. If MAP sensor does not hold vacuum, replace sensor. MAP SENSOR TEST HARNESS TERMINAL IDENTIFICATION Application Positive Terminal Negative Terminal Accord D17 D21 Civic & CRX C11 C14 Prelude 2.0L C11 C14 2.1L D11 D21

Scheme 37

Scheme 38

1. Disconnect 4-wire connector from O2 sensor. Measure resistance between terminals "A" and "B" on sensor. (Scheme 37)and (Scheme 38). If resistance is 15-20 ohms (Accord) or 15-40 ohms (Prelude), go to next step. If resistance is not as specified, replace O2 sensor.
2. Check for continuity to ground on each terminal on O2 sensor. (Scheme 37)and (Scheme 38). If continuity exists, replace O2 sensor. If continuity does not exist, go to next step.
3. Check for continuity between terminals "A" and "C" and between terminals "A" and "D". (Scheme 37)and (Scheme 38). If continuity exists in either case, replace O2 sensor. If continuity does not exist, check wiring to sensor. See TESTS W/CODES article.

1. Prelude 2.0L has 2 O2 sensors. Disconnect O2 sensor from wire harness connector. Start and warm engine to normal operating temperature. Measure voltage between O2 sensor connector and ground.
2. While observing voltage, open throttle fully and then release suddenly. Voltage should be greater than 0.6 volt at wide open throttle and less than 0.4 volt when throttle is quickly released. If voltages are not as specified, check wiring to sensor. If wiring is okay, replace O2 sensor.

Accord & Prelude

1. Connect appropriate test harness between ECU and connector. (Scheme 33)and (Scheme 34). Turn ignition on. Measure voltage between appropriate positive and negative test harness terminals. Refer to «P/S SWITCH TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If voltage is not present, go to step 3). If voltage is present, go to next step.
2. Disconnect 2-wire connector on P/S switch. On Accord, jumper Red wire terminal to Black wire terminal. On Prelude, jumper Blue/Red wire terminal to Black wire terminal. Check voltage. If voltage is not present, replace P/S switch. If voltage is present, repair open in the Red (or Blue/Red) wire between positive ECU terminal and P/S switch or Black wire between P/S switch and ground. Refer to the «P/S SWITCH TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36).
3. Start engine. Turn steering wheel slowly. Measure voltage between positive and negative test harness terminals. See «P/S SWITCH TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If battery voltage is present, P/S switch signal is okay. If battery voltage is not present, go to next step.
4. Turn ignition off. Disconnect test harness "B" connector from main wire harness only, not ECU. Turn ignition switch to ON position. If battery voltage is present, go to next step. If battery voltage is not present, substitute a known good ECU and retest. If prescribed voltage is now available, replace original ECU.
5. Reconnect "B" harness connector to main wire harness and disconnect 2-wire connector on P/S switch. If battery voltage is present, replace P/S switch. If battery voltage is not present, repair short in Red (Blue/Red on Prelude) wire from positive ECU terminal to P/S switch. See «P/S SWITCH TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). P/S SWITCH TEST HARNESS TERMINAL IDENTIFICATION Application Positive Terminal Negative Terminal Accord B8 A26 Prelude (2.0L) B18 A18 Prelude (2.1L) B8 A26

Scheme 39

1. Ensure ignition is off. Disconnect 6-wire connector from TDC/CRANK sensor. Measure resistance between sensor terminals "D" and "E" and terminals "B" and "C". (Scheme 39) If resistance is 350-550 ohms, go to next step. If resistance is not as specified, replace distributor assembly.
2. Check for continuity between body ground and each terminal individually ("B", "C", "D" and "E"). If continuity exists for any terminal, replace distributor assembly.

Scheme 40

1. Disconnect 4-wire connector from TDC/CRANK sensor. Measure resistance between sensor terminals "A" and "B" and between terminals "C" and "D". (Scheme 40) If resistance is between 700-1000 ohms, go to next step. If resistance is not as specified, replace pulse generator assembly.
2. Check for continuity between ground and each terminal. If continuity exists, replace pulse generator assembly.

Scheme 41

1. Disconnect 8-wire TDC/CRANK/CYL sensor connector. Using an ohmmeter, measure resistance between terminals "B" and "F" and between terminals "C" and "G". (Scheme 41) If resistance is 350-700 ohms in each case, go to next step. If resistance is not 350-700 ohms, replace distributor assembly.
2. Check for continuity between body ground and each individual terminal. If continuity exists in any of the wires, replace distributor assembly.

Scheme 42

1. Disconnect 8-wire connector from TDC/CRANK/CYL sensor. Measure resistance between sensor terminals "C" and "D" and between terminals "A" and "B". (Scheme 42) If resistance is between 350-550 ohms, go to next step. If resistance is not as specified, replace distributor assembly.
2. Check for continuity between body ground and each terminal. If continuity exists, replace distributor assembly.

1. On Civic and CRX, hold dashpot diaphragm in retracted position, using a hand-held vacuum pump. On all models, Connect appropriate test harness between ECU and ECU wire harness connector. (Scheme 33)and (Scheme 34).
2. Turn ignition switch to ON position. Measure voltage between ECU positive and negative terminals. See «THROTTLE ANGLE SENSOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). While measuring voltage, open and close throttle. Voltage should be approximately 0.5 volt, with throttle valve at full close position, and 4.5 volts, with throttle at full open position. There should be a smooth transition from 0.5 to 4.5 volts as throttle is opened.
3. If vehicle is equipped with a manual transmission, or is not equipped with an A/T control unit, go to next step. On A/T vehicles equipped with A/T control unit, disconnect 18-wire (22-wire on Accord) connector from A/T control unit. Check voltage again as throttle is opened and closed. If voltage does not fluctuate as specified in step 2), go to next step. If voltage now fluctuates as specified in step 2), replace A/T control unit.
4. If voltage is not as specified, check for short or open in wire between ECU positive terminal and throttle angle sensor. See «THROTTLE ANGLE SENSOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If wire is okay, replace throttle angle sensor. If problem still exists, see TESTS W/CODES article. THROTTLE ANGLE SENSOR TEST HARNESS TERMINAL IDENTIFICATION Application Positive Terminal Negative Terminal Accord D11 D22 Civic & CRX C7 C12 Prelude 2.0L C7 C12 2.1L D11 D22

1. Connect appropriate test harness between ECU and ECU connector. (Scheme 33)and (Scheme 34). Raise vehicle front and support with safety stands. Connect voltmeter between appropriate positive and negative ECU test harness connector terminals. See «VEHICLE SPEED SENSOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36).
2. Turn ignition switch to ON position. Slowly rotate left front wheel. Voltage should pulsate between zero and 5 volts. If voltage pulsates as specified, go to next step. If voltage does not pulsate, check for open or short in wire between ECU positive terminal and speed sensor. See «VEHICLE SPEED SENSOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36). If wire is okay, replace faulty speed sensor or ECU.
3. Substitute a known good ECU and recheck. If condition is rectified, replace original ECU. VEHICLE SPEED SENSOR TEST HARNESS TERMINAL IDENTIFICATION Application Positive Terminal Negative Terminal Accord B10 A26 Civic & CRX B16 A18 Prelude 2.0L B16 A18 2.1L B10 A26

Scheme 43

1. If vehicle starts and continues to run, relay is okay. To test, remove main relay, near under-dash fuse box. Using a jumper from a 12-volt battery power source, connect battery voltage to No. 6 terminal and ground to No. 8 terminal of main relay. (Scheme 43)
2. Check continuity between main relay terminals No. 5 and No. 7. If continuity exists, go to step 3). If continuity does not exist, replace main relay and retest.
3. Connect battery voltage to main relay terminal No. 5 and ground to terminal No. 2. Check continuity between terminals No. 1 and No. 3 of main relay. If continuity exists, go to next step. If continuity does not exist, replace main relay and retest.
4. Connect battery voltage to main relay terminal No. 3 and ground to terminal No. 8. Check continuity between terminals No. 5 and No. 7 of main relay. If no continuity exists, replace main relay and retest. If continuity does exist, main relay is okay. If fuel pump still does not work, test main relay harness. See «FUEL PUMP MAIN RELAY HARNESS»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) under FUEL SYSTEM in this article.

Scheme 44

1. Remove main relay, near under-dash fuse box. Using a jumper from a 12-volt battery power source, connect battery voltage to No. 4 terminal and ground to No. 8 terminal of main relay. (Scheme 44)
2. Check continuity between main relay terminals No. 5 and No. 7. If continuity exists, go to step 3). If continuity does not exist, replace main relay and retest.
3. Connect battery voltage to main relay terminal No. 5 and ground to terminal No. 2. Check continuity between terminals No. 1 and No. 3 of main relay. If continuity exists, go to next step. If continuity does not exist, replace main relay and retest.
4. Connect battery voltage to main relay terminal No. 3 and ground to terminal No. 8. Check continuity between terminals No. 5 and No. 7 of fuel pump main relay. If no continuity exists, replace main relay and retest. If continuity does exist, main relay is okay. If fuel pump still does not work, test main relay harness. See «FUEL PUMP MAIN RELAY HARNESS»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) under FUEL SYSTEM in this article.

BY-PASS CONTROL VALVE SOLENOID (PRELUDE)

See AIR INDUCTION SYSTEMS in this article.

EACV

See IDLE CONTROL SYSTEM in this article.

EGR CONTROL SOLENOID

See EMISSION SYSTEMS & SUB-SYSTEMS in this article.

FAST IDLE SOLENOID (CIVIC & CRX 1.6L)

See IDLE CONTROL SYSTEM in this article.

FUEL INJECTOR SOLENOID(S)

See FUEL CONTROL in this article.

INTAKE CONTROL SOLENOID (ACCORD)

See AIR INDUCTION SYSTEMS in this article.

LOCK-UP CONTROL SOLENOID (CIVIC & CRX 1.5L A/T)

See MISCELLANEOUS CONTROLS in this article.

PURGE CUT-OFF SOLENOID

See EMISSION SYSTEMS & SUB-SYSTEMS in this article.

TANDEM VALVE CONTROL SOLENOID (CIVIC & CRX 1.5L)

See AIR INDUCTION SYSTEMS in this article.

FUEL DELIVERY

Note. For fuel system pressure testing, see appropriate BASIC TESTING article.

Fuel Injector(s)

Disconnect 2-wire connector from injector. Measure resistance between injector terminals. Resistance should be as specified. If not, replace injector(s). See FUEL INJECTOR RESISTANCE TEST table.

FUEL INJECTOR RESISTANCE TEST

Fuel Injector Resistor

Disconnect injector resistor connector. Check resistance between each of injector resistor terminals ("B","C", "D", and "E") and power terminal ("A"). (Scheme 45) Resistance should be 5-7 ohms between each pair of injector resistor terminals. Replace resistor if any resistances are not as specified.

Scheme 45

Scheme 46

Scheme 47

1. Turn ignition off. Disconnect main relay connector. Check for continuity between connector terminal No. 2 and body ground. (Scheme 46)and (Scheme 47). If continuity exists, go to next step. If continuity does not exist, repair open in Black wire from No. 2 terminal.
2. Measure voltage between connector terminals No. 1 (positive) and No. 2 (negative). (Scheme 46)and (Scheme 47). If battery voltage is present, go to next step. If battery voltage is not present, check wiring between battery and main relay as well as EFI/ECU fuse (ECU fuse on Accord and CRX) in underhood relay box.
3. Turn ignition switch to ON position. Measure voltage between connector terminals No. 5 (positive) and No. 2 (negative). (Scheme 46)and (Scheme 47). If battery voltage is present, go to next step. If battery voltage is not present, check wiring from ignition switch and main relay. Check No. 12 fuse (No. 2 on Accord) in dash fuse box and wiring from fuse box to main relay. Repair or replace as necessary.
4. Connect voltmeter to connector terminals No. 4 (positive) (No. 6 on Accord) and No. 2 (negative). (Scheme 46)and (Scheme 47). Turn ignition switch to START position. If specified voltage is present, go to next step. If battery voltage (approximately 10 volts on Accord) is not present, check wiring between ignition switch and main relay. Check No. 1 fuse (A/T) or No. 3 fuse (M/T) (No. 9 fuse on Accord) and wiring from fuse box to main relay. Repair or replace as necessary.
5. Connect a jumper wire between connector terminals No. 5 and No. 7. (Scheme 46)and (Scheme 47). Turn ignition switch to ON position. Fuel pump should operate. If fuel pump does not operate, check wiring to and from fuel pump.

ELECTRIC LOAD DETECTOR (ACCORD, CIVIC & CRX)

1. Connect appropriate ECU test harness between ECU and ECU connector. (Scheme 33)and (Scheme 34). Turn ignition switch to ON position. Measure voltage between positive and negative test harness terminals. See «ELECTRIC LOAD DETECTOR TEST HARNESS TERMINAL IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. (Scheme 35)and (Scheme 36).
2. Turn headlight switch to first position. Voltmeter should read 2.5-3.5 volts. Turn headlight switch to second position. Voltmeter should read 1.5-2.5 volts. If voltage is not as specified, replace electric load detector. ELECTRIC LOAD DETECTOR TEST HARNESS TERMINAL IDENTIFICATION Application Positive Terminal Wire Negative Terminal Wire Accord D10 A26 Civic & CRX B19 A18

Electronic Air Control Valve (EACV)

1. With ignition off, disconnect 2-wire EACV connector. Measure resistance between EACV terminals. If resistance is 8-15 ohms, go to next step. If resistance is not as specified, replace EACV.
2. Check for continuity between each EACV terminal and body ground. If continuity is present, replace EACV.

Fast Idle Control Solenoid (Civic & CRX 1.6L)

1. Disconnect 2-wire connector from fast idle control solenoid valve. Disconnect upper vacuum hose from fast idle control solenoid valve and connect vacuum gauge to valve.
2. Start engine. Energize fast idle control solenoid by connecting battery voltage to Black/Yellow wire and ground to Blue wire of solenoid valve. If manifold vacuum is not present, replace fast idle control solenoid valve.

Fast Idle Valve (Accord & Prelude)

1. Start engine. Remove fast idle valve cover. Place finger on valve seat area and ensure that there is air flow with engine cold and idling. If not, replace fast idle valve and retest.
2. Warm engine to proper operating temperature (cooling fan comes on). Check that valve is completely closed. If valve is leaking, suction can be felt in valve seat area. If any suction is felt, replace valve and recheck.

IGNITION SYSTEM

Note. For basic ignition checks, see appropriate BASIC TESTING article.

Scheme 48

Scheme 49

Scheme 50

Scheme 51

Scheme 52

1. Start engine and warm to normal operating temperature. Disconnect vacuum hose from EGR valve and connect a vacuum gauge. If vacuum is not present, go to step 3). If vacuum is present, disconnect 4-wire connector from control box and check vacuum again.
2. If vacuum is no longer present, inspect for a short to ground in Pink wire (Red wire on Prelude) between EGR control solenoid valve and ECU. If wire is okay, check for faulty ECU. If vacuum is still present, check vacuum hose routing of EGR system. (Scheme 48)and (Scheme 51). If hoses are routed properly, replace EGR control solenoid valve.
3. Disconnect 4-wire connector from control box. Jumper battery voltage to "A" terminal of connector. (Scheme 52) While watching vacuum gauge, ground "B" terminal of connector. (Scheme 52) If approximately 8 in. Hg does not register within one second, go to next step. If specified vacuum registers within one second, solenoid valve is okay.
4. Turn ignition off. Check vacuum hoses to solenoid valve for improper routing, bad connections, leaks, or restrictions. If hoses are okay, disconnect lower hose on EGR control solenoid valve and connect a vacuum gauge to hose. Start engine and allow to idle.
5. If 6-10 in. Hg registers on vacuum gauge, replace EGR control solenoid valve. If specified vacuum does not register on gauge, replace CVC valve.

Scheme 53

1. Start engine and warm to normal operating temperature. Disconnect vacuum hose from EGR valve and connect a vacuum gauge. If vacuum is not present, go to step 2). If vacuum is present, inspect EGR system hose routing and check for short in Red wire between ECU and EGR control solenoid valve. If hose routing and wire are okay, replace solenoid valve.
2. Turn ignition off. Disconnect 4-wire connector from control box. Jumper battery voltage to connector terminal "D" and ground connector terminal "C". (Scheme 53) Start engine and check for vacuum. If approximately 8 in. Hg does not register, go to next step. If specified vacuum does register, solenoid valve is okay.
3. Remove control box cover. Disconnect lower hose on EGR control solenoid valve and connect a vacuum gauge to hose. If 8 in. Hg registers on vacuum gauge, replace EGR control solenoid valve. If specified vacuum does not register on gauge, check vacuum hose routing to CVC valve. If hose routing is okay, replace CVC valve.

EGR Valve

1. Check that all connectors between EGR valve lift sensor and ECU are securely connected. Warm engine to normal operating temperature.
2. Disconnect vacuum hose from EGR valve. Connect a vacuum pump to EGR valve and apply vacuum. EGR valve should hold vacuum and engine should die after vacuum is applied to EGR valve. If not, replace EGR valve.

Scheme 54

1. Connect EGR Valve Lift Sensor Test Harness (07LAJ-PT3020A on Accord, 07GMJ-ML80100 on all others) between EGR valve lift sensor and engine wire harness. (Scheme 54) Turn ignition switch to ON position. Measure voltage between Red (positive) terminal and Green (negative) terminal.
2. If voltage is approximately 5 volts, go to next step. If voltage is not approximately 5 volts, repair open in Yellow/White wire and/or Green/White wire between EGR valve and ECU.
3. Measure voltage between White (positive) terminal and Green (negative) terminal. If voltage is approximately 1.2 (1.0 on Civic and CRX) volts, go to next step. If prescribed voltage is not present, replace EGR valve and retest. Also check for short in White/Black or Yellow wires between ECU and EGR valve lift sensor.
4. Disconnect vacuum hose from EGR valve and connect vacuum pump to EGR valve. While watching voltmeter, slowly apply 8 in. Hg to EGR valve. If voltage increases smoothly from 1.2-4.0 (1.0-4.0 on Civic and CRX) volts as vacuum is applied to EGR valve, EGR valve lift sensor is okay. If voltage does not increase smoothly as vacuum is applied, replace EGR valve.

Charcoal Canister

Connect vacuum gauge to canister purge air hose, located at bottom of canister. (Scheme 55) Start engine and bring engine speed to 3500 RPM. Vacuum should register on gauge within one minute. If not, replace charcoal canister.

Scheme 55

Purge Cut-Off Solenoid Valve

1. Remove vacuum hose from purge control diaphragm valve on charcoal canister and connect vacuum gauge to hose. Start engine. If vacuum is present, go to step 4). If vacuum is not present, go to next step.
2. Warm engine to normal operating temperature (cooling fan comes on). Check for vacuum (On 1.5L, check with throttle slightly opened). If vacuum is present, solenoid is okay. If vacuum is not present, disconnect solenoid valve 2-wire or 4-wire connector. Check vacuum. If manifold vacuum is present, go to next step. If vacuum is not present, inspect vacuum hose routing for kinks or bends. If hose is okay, replace solenoid valve.
3. Inspect for short to ground in positive wire between ECU and solenoid valve connector. See «PURGE CONTROL SOLENOID CONNECTOR IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. If wire is okay, substitute a known good ECU and retest. If symptom goes away, replace original ECU.
4. Disconnect solenoid valve 2-wire or 4-wire connector. Measure voltage between positive and negative terminals on main wire harness. See «PURGE CONTROL SOLENOID CONNECTOR IDENTIFICATION»(/honda/prelude/iii-1989-1992/remont/testing-diagnostics/#engine-controls-systemcomponent-tests-efi) table. If battery voltage is present, replace solenoid valve. If battery voltage is not present, solenoid valve is okay. PURGE CONTROL SOLENOID CONNECTOR IDENTIFICATION Application Positive Terminal Negative Terminal Accord Black/Yellow Red/Green Civic & CRX 1.5L Black/Yellow Green 1.6L Green Black Prelude Black/Yellow Yellow/Black

2-Way Valve

1. Remove fuel filler cap. Remove vapor hose from fuel tank side of 2-way valve and install "T" fitting. Connect vacuum gauge to "T" fitting and a vacuum pump to the end of the hose.
2. Slowly apply vacuum while watching vacuum gauge. Vacuum reading should stabilize momentarily at 0.2-0.6 in. Hg. If so, go to next step. If vacuum stabilizes (valve opens) at less than 0.2 in Hg or greater than 0.6 in. Hg, replace 2-way valve and retest.
3. Move vacuum hose from vacuum to pressure fitting side of vacuum pump. Slowly pressurize vapor line while watching gauge. If pressure stabilizes at 0.4-1.4 in. Hg, valve is okay. If pressure stabilizes at less than 0.4 in. Hg or greater than 1.4 in. Hg, replace 2-way valve and retest.

PCV

Check crankcase ventilation hoses and connections for leaks and clogging. Start engine. With engine at idle, pinch and release PCV hose. Clicking noise should be heard. If no clicking noise is heard, verify if manifold vacuum is present. If manifold vacuum is present, replace PCV valve and recheck.

Throttle Control Dashpot (Civic & CRX)

1. Start engine and warm to normal operating temperature. Disconnect vacuum hose from throttle control dashpot diaphragm and check engine speed.
2. Engine speed should be 2000-3000 RPM. If engine speed is excessively high, adjust engine speed by bending tab on throttle shaft linkage. If engine speed does not change after bending tab, connect vacuum gauge to throttle control dashpot diaphragm vacuum hose and check vacuum. Vacuum should be present.
3. If vacuum is present, replace throttle control dashpot diaphragm and retest. If vacuum is not present, check dashpot diaphragm vacuum hose for proper connection, cracks, or blockage. Check and replace vacuum "T" fitting if necessary (if equipped).
4. Reconnect throttle control dashpot vacuum hose and check idle speed. Idle speed should be as specified. See «ADJUSTMENTS»(/honda/prelude/iii-1989-1992/remont/adjustments/#engine-controls-adjustments) article.

MISCELLANEOUS CONTROLS

Note. Although not considered true "Engine Performance" related systems, some controlled devices may affect driveability if they malfunction.

1. Connect ECU test harness. (Scheme 34) Using an ohmmeter, measure resistance between test harness terminals A8 and A18. (Scheme 36) Resistance should be 14-25 ohms.
2. If resistance is not as specified, check continuity between Yellow wire to ECU terminal A8 and solenoid 2-wire connector. If continuity is not present, repair open in Yellow wire between ECU and sensor terminal connector. If continuity was present, replace faulty lock-up control solenoid.

See also:
• ADJUSTMENTS
• POWER & GROUND TERMINAL IDENTIFICATION
• MISCELLANEOUS CONTROLS