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Home >> Acura >> 2003 >> 3.2CL Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Performance System Self-Diagnostics >> Diagnostic Circuit Check >> Malfunction Indicator Light
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Malfunction Indicator Light

  1. Turn ignition switch on and observe Malfunction Indicator Light (MIL). If MIL always comes on and stays on, go to step  9 . If MIL stays on but sometimes works normally, check for following:
    • Intermittent short in Brown wire between PCM 32-pin "A" harness connector terminal No. 10 (A/T) or PCM 31-pin "E" harness connector terminal No. 16 (M/T) and DLC 16-pin connector terminal No. 9. See Figure , Figure or Figure .
    • Intermittent open in Gray wire between PCM 32-pin "A" harness connector terminal No. 21 (A/T) or PCM 31-pin "E" harness connector terminal No. 27 (M/T) and DLC 16-pin connector terminal No. 7.
    • Intermittent short in Green/Orange wire between PCM 32-pin "A" harness connector terminal No. 18 (A/T) or PCM 31-pin "E" harness connector terminal No. 4 (M/T)and gauge assembly 30-pin harness connector terminal No. 30.

    Repair wiring as necessary. If MIL stays off, go to next step. If MIL stays off but sometimes works normally, check for following malfunctions:

    • Loose No. 9 BACK UP LIGHT, INSTRUMENT LIGHT fuse (7.5-amp) in driver's under-dash fuse/relay box.
    • Loose No. 46 ACG S fuse (15-amp) in under-hood fuse/relay box.
    • Loose No. 1 FUEL PUMP fuse (15-amp) in driver's under-dash fuse/relay box.
    • Intermittent connection at PCM 32-pin "A" harness connector terminal No. 18 (Green/Orange wire) or PCM 31-pin "E" harness connector terminal No. 4 (M/T).
    • Intermittent open in Green/Orange wire between PCM 32-pin "A" harness connector terminal No. 18 (A/T) or PCM 31-pin "E" harness connector terminal No. 4 (M/T) and gauge assembly 30-pin harness connector terminal No. 30.
    • Intermittent short in Yellow/Red wire between PCM 31-pin "C" harness connector terminal No. 19 (A/T) or PCM 31-pin "A" harness connector terminal No. 31 (M/T), MAP sensor 3-pin harness connector terminal No. 3 and counter shaft speed sensor 3-pin harness connector terminal No. 1.
    • Intermittent short in Yellow/Blue wire between PCM 31-pin "C" harness connector terminal No. 28 (A/T) or PCM 31-pin "A" harness connector terminal No. 30 (M/T), TP sensor 3-pin harness connector terminal No. 3, EGR valve lift sensor 3-pin harness connector terminal No. 3, fuel tank pressure sensor 3-pin harness connector terminal No. 1 and main shaft speed sensor 3-pin harness connector terminal No. 1.

      For connector views, see CONNECTOR IDENTIFICATION  . See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. Repair as necessary.

  2. Turn ignition switch off, then on. If oil pressure light is on, go to next step. If oil pressure light is not on, check for a blown No. 9 BACK UP LIGHT, INSTRUMENT LIGHT fuse (7.5-amp) in driver's under-dash fuse/relay box. Also check for short or open in Yellow wire between No. 9 BACK UP LIGHT, INSTRUMENT LIGHT fuse (7.5-amp) in driver's under-dash fuse/relay box and gauge assembly 14-pin harness connector terminal No. 7.
  3. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step  5 .
  4. Turn ignition switch off. Connect fused jumper wire between ground and PCM 32-pin "A" harness connector terminal No. 18 (A/T) or PCM 31-pin "E" harness connector terminal No. 4 (M/T). Turn ignition switch on. If MIL comes on, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM. If MIL does not come on, check for blown MIL bulb or open in Green/Orange wire between PCM 32-pin "A" harness connector terminal No. 18 (A/T) or PCM 31-pin "E" harness connector terminal No. 4 (M/T) and gauge assembly 30-pin harness connector terminal No. 30.
  5. Turn ignition switch off. Disconnect PCM 31-pin "C" harness connector (A/T) or PCM 31-pin "A" harness connector (M/T). Check for continuity between ground and PCM 31-pin "C" harness connector terminals No. 19 (Yellow/Red wire) and 28 (Yellow/Blue wire - A/T) or PCM 31-pin "A" harness connector terminals No. 31 (Yellow/Red wire) and 30 (Yellow/Blue wire - M/T) individually. If continuity is present, go to next step. If continuity is not present, go to step  7 .
  6. Disconnect harness connectors from each of following sensors one at a time while checking for continuity between ground and PCM 31-pin "C" harness connector terminals No. 19 (Yellow/Red wire) and 28 (Yellow/Blue wire - A/T) or PCM 31-pin "A" harness connector terminals No. 31 (Yellow/Red wire) and 30 (Yellow/Blue wire - M/T) individually:
    • Countershaft speed sensor
    • EGR valve lift sensor
    • Fuel Tank Pressure (FTP) sensor
    • Mainshaft speed sensor
    • Manifold Absolute Pressure (MAP) sensor
    • TP sensor

    If continuity is present, repair short in Yellow/Red wire between PCM and MAP sensor or countershaft speed sensor or repair short in Yellow/Blue wire between PCM and EGR position sensor, FTP sensor, mainshaft speed sensor or TP sensor. See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS If continuity is not present, replace sensor that was disconnected when continuity was no longer present.

  7. Disconnect fuel injector and IAC valve connectors. Turn ignition switch on. Measure voltage between ground and PCM 25-pin "B" harness connector terminals No. 1 and 9 (Yellow/Black wire - A/T) or PCM 31-pin "A" harness connector terminals No. 2 and 3 (Yellow/Black wire - M/T) individually. If battery voltage is present, go to next step. If battery voltage is not present, check for following problems:
    • Open in Yellow/Black wire between PCM and PGM-FI main relay.
    • Poor connections at PGM-FI main relay.
    • Defective PGM-FI main relay.

    Repair or replace component as necessary.

  8. Turn ignition switch off. Reconnect sensor connectors, then reconnect PCM harness connector. Turn ignition switch on. Measure voltage between ground and PCM 25-pin "B" harness connector terminals No. 2 and 10 (Black wire) and terminals No. 20 and 22 (Brown/Yellow wire - A/T) or PCM 31-pin "A" harness connector terminals No. 4 and 5 (Black wire) and terminals No. 25 and 26 (Brown/Yellow wire - M/T). If less than one volt is present, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM. If one volt or more is present, repair open in appropriate wiring between ground terminal G101 and PCM 25-pin "B" harness connector terminals No. 2, 10, 20 or 22 or PCM 31-pin "A" harness connector terminals No. 4, 5, 25, or 26.
  9. Connect scan tool to DLC. Turn ignition switch on. Check for DTCs. If any DTCs are present, diagnose as directed by DIAGNOSTIC TROUBLE CODE DEFINITIONS  table. If DTCs are not present, turn ignition switch off. Disconnect PCM 32-pin "A" harness connector (A/T) or PCM 31-pin "E" harness connector (M/T). Check continuity between ground and 16-pin DLC terminal No. 7 (Gray wire). If continuity is not present, go to next step. If continuity is present, repair short in Gray wire between 16-pin DLC terminal No. 7 and PCM 32-pin "A" harness connector terminal No. 21 (A/T) or PCM 31-pin "E" harness connector terminal No. 27 (M/T).
  10. Check for continuity in Gray wire between PCM 32-pin "A" harness connector terminal No. 21 (A/T) or PCM 31-pin "E" harness connector terminal No. 27 (M/T) and 16-pin DLC terminal No. 7. If continuity is present, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM. If continuity is not present, repair open in Gray wire between 16-pin DLC terminal No. 7 and PCM. Check for DTCs. If any DTCs are present, diagnose as directed by DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  11. Turn ignition switch off, then on. Measure voltage between ground and PCM 32-pin "A" harness connector terminal No. 10 (Brown wire - A/T) or PCM 31-pin "E" harness connector terminal No. 16 (Brown wire - M/T). If about 5 volts are present, go to next step. If about 5 volts are not present, repair short in Brown wire between 16-pin DLC terminal No. 9 and PCM.
  12. Turn ignition switch off. Disconnect PCM 32-pin "A" harness connector (A/T) or PCM 31-pin "E" harness connector (M/T). Turn ignition switch on. If MIL comes on, repair short in Green/Orange wire between PCM 32-pin "A" harness connector terminal No. 18 (A/T) or PCM 31-pin "E" harness connector terminal No. 4 (M/T) and gauge assembly 30-pin harness connector terminal No. 30. If MIL does not come on, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.
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