P1639

Description
5-VOLT REFERENCE "B" CIRCUIT

PCM uses 5-volt reference "B" circuit as a sensor feed for
A/C refrigerant pressure sensor. PCM monitors voltage on this circuit.
If PCM senses voltage out of tolerance, DTC P1639 sets.

Symptoms
You likely won't notice any drivability problems.

Causes

• PCM detects an out of tolerance condition on 5-volt reference
  "B"circuit.

Solutions

• Check for faulty connections or damaged harness on AC pressure sensor.
• Check for shorts in AC pressure sensor wires
• Replace A/C pressure sensor.