Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside insulation. Check for:

• Backed out connector terminals or broken down insulation.
• If connections and harness are okay, monitor voltage on spark reference circuit using DVOM while moving related wiring harness and connectors with engine idling. This may assist in isolating malfunction.

Fig 1: Code P0321 Schematic (3.8L FWD Van) Spark Reference Circuit

Fig 2: Code P0321 Flow Chart (3.8L FWD Van) Spark Reference Circuit