Diagnostic Aids
WARNING: This page is about a different car, the 2000 Isuzu Rodeo and 2000 Isuzu Amigo. However, it is still accessible from the selected car via links, so may be relevant.
Check for poor connections at PCM and A/C pressure sensor. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage. Also check for open circuits, shorts to ground and shorts to voltage.