Code 18 - Ignition Timing Adjuster
- Turn ignition off. Remove ACG fuse (No. 15, 7.5-amp) from underdash fuse box for 10 seconds to reset ECM. Retrieve codes. If Code 18 does not appear, problem is intermittent. Inspect for poor connections at ECM connector and ignition timing adjuster connector. Test-drive vehicle and retest.
- If Code 18 exists, turn ignition off. Unplug ignition timing adjuster 3-pin connector from control box. See Fig 1
.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Measure resistance between terminals "A" and "C" of ignition timing adjuster. Resistance should be 3500-6500 ohms. If resistance is as specified, go to step 4). If resistance is not 3500-6500 ohms, replace ignition timing adjuster.
- Measure and record resistance between terminals "A" and "B" on timing adjuster side of harness connector. Measure and record resistance between terminals "B" and "C" on same side of connector. Add both resistance values together.
- If total resistance value is not 3500-6500 ohms, replace ignition timing adjuster. If resistance is 3500-6500 ohms, turn ignition on. Measure voltage between Yellow/White (+) and Green/White (-) wire terminals on wiring harness side of connector. If voltage is about 5 volts, go to step 8).
- If voltage is not about 5 volts, measure voltage between ground and Yellow/White wire terminal. If voltage is about 5 volts, repair open in Green/White wire between ECM terminal D22 and ignition timing adjuster connector.
- If voltage is not about 5 volts, turn ignition off. Connect ECM Test Harness (07LAJ-PT3010A
) between ECM and ECM connectors. See Figure
. Turn ignition on. Measure voltage between test terminals D20 (+) and D22 (-). If voltage is about 5 volts, repair open in Yellow/White wire between ECM terminal D20 and ignition timing adjuster. If voltage is not about 5 volts, temporarily substitute known good ECM, then retest system.
- If voltage between Yellow/White and Green/White wire terminals in step 5) was about 5 volts, turn ignition off. Reconnect ignition timing adjuster wiring. Connect ECM Test Harness (07LAJ-PT3010A
) between ECM and ECM harness.
- Turn ignition on. Measure voltage between ECM terminals D8 (+) and D22 (-). If voltage is not 0.5-4.5 volts, repair open or short in Blue/Yellow wire between ECM connector terminal D8 and ignition timing adjuster. If voltage is 0.5-4.5 volts, temporarily substitute known good ECM, then retest system.