G 2500 3/4 Ton Van V8-350 5.7L VIN K TBI (1995)
Engine Control Module: Component Tests and General Diagnostics
*** This Procedure updated per TSB #41-65-33 ***
If a diagnostic chart indicates that a PCM connection or PCM is the cause of a problem and the PCM is replaced, but does not correct the problem, one
of the following may be the reason:
There is a problem with the PCM terminal connections
The terminals may need to be removed from the connector in order to check them properly.
The PCM is not correct for the application
The incorrect components may cause a malfunction and may, or may not set a DTC.
The problem is intermittent
This means that the problem is not present at the time the system is being checked. In this case, refer to Diagnosis by Symptom and make a careful
physical inspection of all portions of the system involved. Refer to Diagnosis by Symptom / Intermittents. See: Powertrain
Management/Computers and Control Systems/Testing and Inspection
Shorted solenoid. relay coil. or harness
Solenoids and relays are turned "ON" and "OFF" by the PCM using internal electronic switches called "drivers." Each driver is part of a group of
four called "quad-drivers." Failure of one driver can damage any other driver in the set.
A shorted solenoid, relay coil, or harness will not damage the "quad-drivers" in this PCM1 but will cause the circuit and controlled component to
be inoperative. When the circuit fault is not present or has been repaired, the "quad-driver" will again operate in a normal manner due to its fault
protected design. It a fault has been repaired in a circuit, controlled by a "quad-driver," the original PCM should be reinstalled and the circuit
checked for proper operation. PCM replacement will not be necessary if the repaired circuit or component operates correctly.
The J 39200 tester, or equivalent, provides a fast, accurate means of checking for a shorted coil, or a short to battery voltage.
