Engine Controls - Tests W/codes - Tests: Other Honda Prelude V

CIRCUIT TESTS

Note. Before performing any diagnostic test, refer to TESTS W/CODES - INTRODUCTION article for diagnostic system functions and system diagnostic procedures.

Note. Different Honda models are equipped with either an Engine Control Module (ECM) or a Powertrain Control Module (PCM). ECM will be referred to as a PCM.

Note. When there is no DTC stored, MIL will stay on if the SCS Service Connector (07PAZ-0010100 ) is connected and ignition is on.

When directed by testing procedure to install test equipment, see TEST EQUIPMENT in TESTS W/CODES - INTRODUCTION article.

Malfunction Indicator Light (MIL) Never Comes On, Even For 2 Seconds After Ignition Is Turned On

1. Turn ignition on. If charge system light is on, go to next step. If charge system light is not on, replace No. 14 ECU/EAT ECU (15-amp) fuse and repair short or open in Black/Yellow wire between No. 14 ECU/EAT ECU (15-amp) fuse and gauge assembly. See «WIRING DIAGRAMS»(ref-16355) article.
2. Try to start engine. If engine starts, go to next step. If engine does not start, turn ignition switch to ON position. Using backprobe set, measure voltage between ground and PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A23 (Black wire), individually. see scheme 1 If less than one volt exists, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If one volt or more exists, repair open in suspect Black wire between PCM and ground connection G101, located at thermostat housing. See «WIRING DIAGRAMS»(ref-16355) article.
3. Turn ignition off. Using backprobe kit, connect a fused jumper wire between ground and PCM 32-pin connector "A" terminal A18 (Gray/Red wire). see scheme 1 Turn ignition on. If MIL comes on, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If MIL does not come on, replace MIL bulb and/or repair open in Gray/Red wire between PCM 32-pin connector "A" terminal A18 and gauge assembly. NOTE: MIL will stay on when no DTC is stored and SCS Service Connector (07PAZ-0010100 ) is connected and ignition is on.

Malfunction Indicator Light (MIL) Stays On Or Comes On After 2 Seconds

1. If symptom is intermittent, check for: A loose No. 4 ACG-S (10-amp) fuse located in underdash fuse/relay box. A loose No. 23 FUEL PUMP (15-amp) fuse located in underdash fuse/relay box. An intermittent short in Red/White wire between PCM 31-pin connector "C" terminal C7 and service check 2-pin connector located at right side of center console behind access cover. An intermittent short in Gray/Red wire between PCM 32-pin connector "A" terminal A18 and gauge assembly 16-pin Blue connector "B" terminal B16. See «WIRING DIAGRAMS»(ref-16355) article. An intermittent short in Yellow/Red wire between PCM 16-pin connector "D" terminal D4 and MAP sensor. See «WIRING DIAGRAMS»(ref-16355) article. An intermittent short in Yellow/Blue wire between PCM 16-pin connector "D" terminal D10 and TP sensor, EGR valve lift sensor and/or fuel tank pressure sensor. See «WIRING DIAGRAMS»(ref-16355) article. A faulty PGM-FI main relay. Perform repairs as necessary and recheck MIL operation. If no problems are found, go to next step.
2. Connect OBD-II scan tool to Data Link 16-pin Connector (DLC) located at right side of center console behind access cover. see scheme 5 Turn ignition on. Read DTCs. See «RETRIEVING CODES»(ref-16345-S38702527312000122900000) in TESTS W/CODES - INTRODUCTION article. If DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(ref-16350-S13513630952002082600000) table. After identifying DTC, go to Diagnostic Trouble Code (DTC) test. If DTCs are not present, go to next step. NOTE: An open or short in Light Green wire between PCM 31-pin connector "C" terminal C8 and DLC terminal No. 15 will keep OBD-II scan tool from communicating with PCM. see scheme 3and see scheme 5. If this occurs, go to step 3).
3. Turn ignition off. Connect SCS Service Connector (07PAZ-0010100 ) to service check 2-pin connector. Turn ignition on. If MIL indicates DTCs, repair open or short in Light Green wire between PCM 31-pin connector "C" terminal C8 and DLC terminal No. 15. see scheme 3and see scheme 5. If DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(ref-16350-S13513630952002082600000) table. After identifying DTC, go to Diagnostic Trouble Code (DTC) test. If MIL does not indicate DTCs, go to next step.
4. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 7).
5. Turn engine off and ignition on. Using backprobe set, measure voltage between PCM 31-pin connector "C" terminal C7 (Red/White wire) and PCM 16-pin connector "D" terminal D11 (Green/Black wire). see scheme 3and see scheme 4. If about 5.0 volts exists, go to next step. If about 5.0 volts does not exist, repair short in Red/White wire between PCM 31-pin connector "C" terminal C7 and service check connector. See «WIRING DIAGRAMS»(ref-16355) article.
6. Turn ignition off. Disconnect PCM 32-pin connector "A". Turn ignition on. If MIL is on, repair short in Gray/Red wire between PCM 32-pin connector "A" terminal A18 and MIL. See «WIRING DIAGRAMS»(ref-16355) article. If MIL is not on, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.
7. Inspect No. 4 ACG-S (15-amp) fuse located in underdash fuse/relay box. If fuse is okay, go to next step. If fuse is open, repair short in White/Green wire between fuse and PGM-FI main relay. See «WIRING DIAGRAMS»(ref-16355) article. Replace fuse.
8. Inspect No. 23 FUEL PUMP (15-amp) fuse located in SRS fuse block. SRS fuse block is located at left kick panel, above underdash fuse/relay box. If fuse is okay, go to next step. If fuse is open, repair short in Red/Orange wire between fuse and PGM-FI main relay. See «WIRING DIAGRAMS»(ref-16355) article. Replace fuse.
9. Turn ignition on. While observing MIL, disconnect 3-pin connector from Manifold Absolute Pressure (MAP) sensor, Throttle Position (TP) sensor, EGR valve lift sensor and Fuel Tank Pressure (FTP) sensor, one at a time. If MIL does not go off, go to next step. If MIL goes off, replace sensor that caused MIL to go off.
10. Turn ignition off. Disconnect PCM 16-pin connector "D". Check for continuity between ground and PCM 16-pin connector "D" terminal D4 (Yellow/Red wire) and terminal D10 (Yellow/Blue wire), individually. see scheme 4 If continuity does not exist, go to next step. If continuity exists, repair short in Yellow/Red wire between PCM connector terminal D4 and MAP sensor, or Yellow/Blue wire between PCM connector terminal D10 and TP sensor, EGR valve lift sensor or FTP sensor. See «WIRING DIAGRAMS»(ref-16355) article.
11. Turn ignition off. Disconnect fuel injector connectors and IAC valve connector. Turn ignition on. Using backprobe set, measure voltage between ground and PCM 32-pin connector "A" terminal A11 (Yellow/Black wire) and terminal A24 (Yellow/Black wire), individually. see scheme 1 If battery voltage exists, go to next step. If battery voltage does not exist, check for poor connections at PGM-FI main relay or repair open in Yellow/Black wire(s) between PCM 32-pin connector "A" terminal A11 or terminal A24 and PGM-FI main relay. See «WIRING DIAGRAMS»(ref-16355) article. If connections and wires are okay, check PGM-FI main relay. See «SYSTEM/COMPONENT TESTS»(ref-16351) article.
12. Turn ignition off and reconnect all sensor connectors. Reconnect PCM 16-pin connector "D". Turn ignition on. Using backprobe set, measure voltage between ground and PCM 32-pin connector "A" terminal A9 (Brown/Black wire) and terminal A22 (Brown/Black wire), individually. see scheme 1 If voltage is less than one volt, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If voltage for either terminal is one volt or more, repair open in Brown/Black wire between PCM connector terminal A9 and/or terminal A22 and ground connection G101, located at thermo-stat housing. See «WIRING DIAGRAMS»(ref-16355) article.

Scheme 25

1. Turn ignition on. Check MAP sensor using scan tool. If about zero in. Hg is indicated, go to next step. If about zero in. Hg is not indicated, problem is intermittent. Check for poor connections or loose wires at MAP sensor connector and PCM connector. See «WIRING DIAGRAMS»(ref-16355) article.
2. Turn ignition off and disconnect MAP sensor 3-pin connector. Turn ignition on. Check MAP sensor using OBD-II scan tool. If about zero in. Hg is indicated, go to next step. If about zero in. Hg is not indicated, replace MAP sensor.
3. Measure voltage between MAP sensor connector terminals No. 1 (Yellow/Red wire) and No. 2 (Green/White wire). (Scheme 25) If about 5.0 volts exists, go to next step. If about 5.0 volts does not exist, repair open in Yellow/Red wire between PCM 16-pin connector "D" terminal D4 and MAP sensor connector terminal No. 1. see scheme 4and (Scheme 25). See «WIRING DIAGRAMS»(ref-16355) article.
4. Turn ignition off. Disconnect 16-pin PCM connector "D". Check for continuity between ground and MAP sensor 3-pin connector terminal No. 3 (Red/Green wire). If continuity does not exist, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If continuity exists and vehicle is equipped with Active Torque Transfer System (ATTS), go to next step. If continuity exists and vehicle is not equipped with ATTS, repair short in Red/Green wire between PCM 16-pin connector "D" terminal D3 and MAP sensor connector terminal No. 3.
5. Ensure ignition is off. Disconnect ATTS control unit 22-pin Blue connector. ATTS control unit is located under passenger-side footwell carpet, next to PCM. Check for continuity between ground and MAP sensor 3-pin connector terminal No. 3 (Red/Green wire). If continuity does not exist, replace ATTS control unit. If continuity exists, repair short in Red/Green wire between PCM 16-pin connector "D" terminal D3, ATTS control unit 22-pin connector "B" terminal B20 and MAP sensor 3-pin connector terminal No. 3. See «WIRING DIAGRAMS»(ref-16355) article.

Random Misfire Occurs During Low RPM & Low Engine Load

Check for

1. EGR system malfunction. See «DTC P0401: EGR INSUFFICIENT FLOW»(ref-16350-S25546885592000122900000) .
2. Correct fuel pressure. See FUEL SYSTEM in «BASIC TESTING»(ref-16344) article.
3. Correct valve adjustment. See «ADJUSTMENTS»(ref-16352) article.
4. Crankshaft position sensor malfunction.

Random Misfire Occurs During Acceleration

Check for

1. Worn or broken spark plug wires.
2. Worn or damaged distributor ignition housing.
3. Correct fuel pressure. See FUEL SYSTEM in «BASIC TESTING»(ref-16344) article.
4. Malfunctioning ignition control module. See «SYSTEM/COMPONENT TESTS»(ref-16351) article.

Random Misfire Occurs During High Engine RPM & Load, Or Under Random Conditions

Check for

1. Correct fuel pressure. See FUEL SYSTEM in «BASIC TESTING»(ref-16344) article.
2. Worn or broken spark plug wires.
3. Worn or damaged distributor ignition housing.
4. Malfunctioning ignition control module. See «SYSTEM/COMPONENT TESTS»(ref-16351) article.
5. Correct valve adjustment. See «ADJUSTMENTS»(ref-16352) article.
6. Crankshaft position sensor malfunction.

Other Possible Causes

Check for

1. Insufficient fuel pressure or inadequate fuel flow.
2. Clogging, blocked or leaking fuel line.
3. Clogging fuel filter.
4. Fuel pressure regulator stuck open.
5. EGR system malfunction.
6. Distributor malfunction.
7. An open or leaking ignition coil wire.
8. Ignition Control Module (ICM) malfunction.
9. Carbon deposits on valves.
10. Low engine compression.
11. A VTEC system malfunction.
12. Fuel octane level less than specification or very low fuel level.