Diagnostic Aids

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

• Poor Connection Or Damaged Harness
  
  Inspect control module harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
• Intermittent Test
  
  If connections and harness are okay, monitor a DVOM connected between affected terminal and ground while moving related connectors and wiring harness. If failure is induced, voltage reading will change.

Fig 1: Code P1406 Schematic ("S" & "T" Series 4.3L - VIN W) EGR Valve Pintle Position

Fig 2: Code P1406 Flow Chart 1 Of 2 ("S" & "T" Series 4.3L - VIN W) EGR Valve Pintle Position