Idle Control System: Diagnosis Honda Pilot I

DTC Troubleshooting

DTC Troubleshooting Index

Note. If DTC P1519 is stored at same time as DTC P0505, troubleshoot DTC P1519 first, then recheck for DTC P0505.

Scheme 179

1. Start the engine. Hold the engine at 3,000 RPM with no load (in Park or neutral) until the radiator fan comes on.
2. Check the engine speed at idle with no-load conditions: headlights, blower fan, rear window defogger, radiator fan, and air conditioner off. Is the engine running at 730+/-50 RPM? YES -Intermittent failure, system is OK at this time. NO -If the idle speed is less than 680 RPM, go to step 3; if it's 780 RPM or higher, go to step 4.
3. Disconnect the idle air control (IAC) valve 3P connector. Does the engine speed increase or fluctuate? YES -Adjust the idle speed (see «Idle Speed Adjustment»(ref-173998-S11455734482005041500000) ). If the idle will not adjust properly, clean the passage in the throttle body, and then adjust the idle. NO -Replace the IAC valve.
4. Turn the ignition switch OFF.
5. Remove the intake air duct from the throttle body.
6. Start the engine, and let it idle.
7. Put your finger on the lower port (A) in the throttle body. Does the engine speed drop below 780 RPM? YES -Adjust the idle speed (see «Idle Speed Adjustment»(ref-173998-S11455734482005041500000) ). If the idle will not adjust properly, replace the IAC valve (see «THROTTLE BODY DISASSEMBLY/REASSEMBLY»(ref-173999-S37099059522005041500000) ), and then adjust the idle. NO -With the throttle valve completely closed, check for vacuum leaks, and repair as necessary.

Scheme 180

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Scheme 184

Scheme 185

1. Reset the PCM (see «HOW TO RESET THE PCM»(ref-173995-S09390407622005041500000) ).
2. Turn the ignition switch ON (II). Is DTC P1519 indicated? YES -Go to step 3. NO -Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the IAC valve and at the PCM.
3. Turn the ignition switch OFF.
4. Disconnect the IAC valve 3P connector.
5. Turn the ignition switch ON (II).
6. Measure voltage between IAC valve 3P connector terminal No. 2 and body ground. Is there battery voltage? YES -Go to step 7. NO -Repair open in the wire between the IAC valve and the PGM-FI main relay.
7. Turn the ignition switch OFF.
8. Check for continuity between body ground and IAC valve 3P connector terminal No. 1. Is there continuity? YES -Go to step 9. NO -Repair open in the wire between the IAC valve and G101.
9. Disconnect PCM connector B (125P).
10. Check for continuity between body ground and PCM connector terminal B23. Is there continuity? YES -Repair short in the wire between the IAC valve and the PCM (B23). NO -Go to step 11.
11. Connect IAC valve 3P connector terminal No. 3 to body ground with a jumper wire.
12. Check for continuity between PCM connector terminal B23 and body ground. Is there continuity? YES -Go to step 13. NO -Repair open in the wire between the IAC valve and the PCM (B23).
13. Remove the jumper wire from the IAC valve 3P connector, then reconnect the IAC valve 3P connector.
14. Turn the ignition switch ON (II).
15. Measure voltage between body ground and PCM connector terminal B23. Is there battery voltage? YES -Substitute a known-good PCM and recheck (see «HOW TO SUBSTITUTE THE PCM FOR TESTING»(ref-173995-S22023424662005041500000) ). If the symptom/indication goes away, replace the original PCM. NO -Replace the IAC valve.

Scheme 186

Scheme 187

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Scheme 189

Scheme 190

1. Turn the ignition switch OFF.
2. Disconnect the A/C pressure switch 2P connector.
3. Turn the ignition switch ON (II).
4. Measure voltage between PCM connector terminals A27 and B20. Is there about 5 V or battery voltage? YES -Go to step 5. NO -Go to step 12 .
5. Turn the ignition switch OFF.
6. Reconnect the A/C pressure switch 2P connector.
7. Turn the ignition switch ON (II).
8. Momentarily connect PCM connector terminals A17 and B20 with a jumper wire several times. Is there a clicking noise from the A/C compressor clutch? YES -Go to step 9. NO -Go to step 15 .
9. Start the engine.
10. Turn the blower switch ON.
11. Turn the A/C switch ON. Does the A/C operate? YES -The air conditioning signal is OK. NO -Go to step 16.
12. Turn the ignition switch OFF.
13. Disconnect PCM connector A (32P).
14. Check for continuity between body ground and PCM connector terminal A27. Is there continuity? YES -Repair short in the wire between the PCM (A27) and the A/C pressure switch. NO -Substitute a known-good PCM and recheck (see «HOW TO SUBSTITUTE THE PCM FOR TESTING»(ref-173995-S22023424662005041500000) ). If prescribed voltage is now available, replace the original PCM. If not, check the A/C system for other symptoms.
15. Momentarily connect under-hood fuse/relay box 16P connector terminal No. 11 to body ground with a jumper wire several times. Is there a clicking noise from the A/C compressor clutch? YES -Repair open in the wire between the PCM (A17) and the A/C clutch relay. NO -Check the A/C system for other symptoms.
16. Measure voltage between PCM connector terminals A27 and B20. Is there less than 1.0 V? YES -Substitute a known-good PCM and recheck (see «HOW TO SUBSTITUTE THE PCM FOR TESTING»(ref-173995-S22023424662005041500000) ). If the symptom/indication goes away, replace the original PCM. If not, inspect the air conditioning system. NO -Repair open in the wire between the PCM (A27) and the A/C pressure switch.

Scheme 191

Scheme 192

Scheme 193

Scheme 194

1. Disconnect the alternator 4P connector.
2. Turn the ignition switch ON (II).
3. Measure voltage between PCM connector terminals B20 and C5. Is there about 5 V? YES -Go to step 4. NO -Go to step 13 .
4. Turn the ignition switch OFF.
5. Reconnect the alternator 4P connector.
6. Start the engine. Hold the engine at 3,000 RPM with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
7. Measure voltage between PCM connector terminals B20 and C5. Does the voltage decrease when the headlights and rear window defogger are turned on? YES -The ALT FR signal is OK. NO -Go to step 8.
8. Turn the ignition switch OFF.
9. Disconnect PCM connector C (31P).
10. Disconnect the alternator 4P connector.
11. Connect alternator 4P connector terminal No. 4 to body ground with a jumper wire.
12. Check for continuity between body ground and PCM connector terminal C5. Is there continuity? YES -Test the alternator (see «CHARGING CIRCUIT»(ref-162803-S41606332012004061000000) ). NO -Repair open in the wire between the PCM (C5) and the alternator.
13. Turn the ignition switch OFF.
14. Disconnect PCM connector C (31P).
15. Check for continuity between body ground and PCM connector terminal C5. Is there continuity? YES -Repair short in the wire between the PCM (C5) and the alternator. NO -Substitute a known-good PCM and recheck (see «HOW TO SUBSTITUTE THE PCM FOR TESTING»(ref-173995-S22023424662005041500000) ). If voltage is normal, replace the original PCM.

Scheme 195

1. Shift the transmission into Park or neutral.
2. Measure voltage between PCM connector terminals A24 and B20 with the ignition switch in the START (III) position. Is there battery voltage? YES -The starter switch signal is OK. NO -Go to step 3.
3. Inspect the No. 13 STARTER SIGNAL (7.5A) fuse in the driver's under-dash fuse/relay box. Is the fuse OK? YES -Repair open in the wire between the PCM (A24) and the No. 13 STARTER SIGNAL (7.5A) fuse. NO -Repair short in the wire between the PCM (A24) and the No. 13 STARTER SIGNAL (7.5A) fuse or the PGM-Fl main relay. Replace the No. 13 STARTER SIGNAL (7.5A) fuse.

Scheme 196

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Scheme 200

Scheme 201

1. Turn the ignition switch ON (II).
2. Measure voltage between PCM connector terminals A26 and B20. Is there less than 1.0 V? YES -Go to step 3. NO -Go to step 6 .
3. Start the engine.
4. Turn the steering wheel to the full lock position.
5. Measure voltage between PCM connector terminals A26 and B20. Is there battery voltage? YES -The PSP switch signal is OK. NO -Go to step 11 .
6. Turn the ignition switch OFF.
7. Disconnect the PSP switch 2P connector.
8. Turn the ignition switch ON (II).
9. At the harness side, connect PSP switch 2P connector terminals No. 1 and No. 2 with a jumper wire.
10. Measure voltage between PCM connector terminals A26 and B20. Is there less than 1.0 V? YES -Replace the PSP switch. NO -Check for an open in the wire between the PCM (A26) and the PSP switch or, an open in wire between the PSP switch and G201.
11. Turn the ignition switch OFF.
12. Disconnect the PSP switch 2P connector.
13. Turn the ignition switch ON (II).
14. Measure voltage between PCM connector terminals A26 and B20. Is there battery voltage? YES -Replace the PSP switch. NO -Go to step 15.
15. Turn the ignition switch OFF.
16. Disconnect the PCM connector A (32P).
17. Check for continuity between body ground and PCM connector terminal A26. Is there continuity? YES -Repair short in the wire between the PCM (A26) and the PSP switch. NO -Substitute a known-good PCM and recheck (see «HOW TO SUBSTITUTE THE PCM FOR TESTING»(ref-173995-S22023424662005041500000) ). If voltage is normal, replace the original PCM.

Scheme 202

1. Check the brake lights. Are the brake lights on without pressing the brake pedal? YES -Inspect the brake pedal position switch (see «BRAKE PEDAL POSITION SWITCH TEST»(ref-174044-S07397927292005050300000) ). NO -Go to step 2.
2. Press the brake pedal. Do the brake lights come on? YES -Go to step 4 . NO -Go to step 3.
3. Inspect the STOP (20A) fuse in the under-hood fuse/relay box. Is the fuse OK? YES -Repair open in the wire between the brake pedal position switch and the STOP (20A) fuse. Inspect the brake pedal position switch (see «BRAKE PEDAL POSITION SWITCH TEST»(ref-174044-S07397927292005050300000) ). Go to step 4. NO -Repair short in the wire between the PCM (A32) and the STOP (20A) fuse. Replace the STOP (20A) fuse. Go to step 4.
4. Measure voltage between PCM connector terminals A32 and B20 with the brake pedal pressed. Is there battery voltage? YES -The brake pedal position switch signal is OK. NO -Repair open in the wire between the PCM (A32) and the brake pedal position switch.