Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Using scan tool, check manifold absolute pressure. If indicated pressure is 12.8 in. Hg. or less, problem is intermittent, system is okay at this time. If indicated pressure is more than specification, replace MAP sensor.
Scheme 11
- Perform PCM reset procedure. See «PCM RESET PROCEDURE/CLEARING DTCS»(ref-16284-S05371059252001010800000). Start engine. Turn headlights on. If DTC P1297 is indicated, go to next step. If DTC P1297 is not indicated, problem is intermittent, system is okay at this time. Check for poor connections or loose wires between at PCM and ELD connectors. ELD is located in underhood fuse/relay box. See the «WIRING DIAGRAMS»(ref-16319) article.
- Turn ignition and headlights off. Disconnect ELD 3-pin connector. Turn ignition on. Measure voltage between ground and ELD connector terminal No. 1 (Black/White wire). (Scheme 11) If battery voltage exists, go to next step. If battery voltage does not exist, repair open in wire between underdash fuse/relay box and ELD.
- Measure voltage between ground and ELD connector terminal No. 3 (Green/Red wire). (Scheme 11) If approximately 4.5 volts does not exist, go to next step. If approximately 4.5 volts eists, replace ELD.
- Turn ignition off. Disconnect PCM 16-pin connector "D". see scheme 2 Check for continuity between ground and PCM connector terminal D16 (Green/Red wire). If continuity exists, repair short in Green/Red wire between PCM connector terminal D16 and ELD. See the «WIRING DIAGRAMS»(ref-16319) article. If continuity does not exist, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.