S15/T15 4WD Jimmy V6-262 4.3L VIN Z (1992)
Quad Driver: Description and Operation
Quad/Output Driver Module
The Control Module in this vehicle controls most components with electronic switches which complete a ground circuit when turned on.
When the switches are arranged in groups of 4, they can independently control up to 4 outputs and are called Quad Drivers.
When the switches are arranged in groups of 7, they can independently control up to 7 outputs and are called Output Drivers.
Not all outputs are always used.
Shorted solenoid. relay coil. or harness- Solenoids and relays are turned "ON" and "OFF" by the PCM or VCM 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 VCM/PCM, 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. If a fault has been repaired in a circuit, controlled by a "quad-driver," the original VCM/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 DVM testers, or equivalent, provide a fast, accurate means of checking for a shorted coil, or a short to battery voltage.
The replacement VCM/PCM may be faulty - After the VCM/PCM is replaced, the system should be rechecked for proper operation. If the diagnostic
chart again indicates that the VCM/PCM is the problem, substitute a known good VCM/PCM.
