Test Description

NOTE: Test numbers refer to numbers on diagnostic chart.

If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1640 also.
If QDM No. 1 symptoms are present, checks on Code P1640 (2 Of 2) chart should isolate cause of fault.
This test will determine which circuit is out of specification.
Determines if problem is circuit or component.
As factory installed PCM is protected with an internal circuit breaker, it is highly unlikely that PCM needs to be replaced.

Fig 1: Code P1640 Schematic (3.8L) QDM No. 1 Circuit

Fig 2: Code P1640 Diagnostic Flow Chart (3.8L) QDM No. 1 Circuit