Diagnostic Aids

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Fig 1: Code 56, Schematic, Quad-Driver "B" Fault 3.8L (1 of 2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 56, Flow Chart, Quad-Driver "B" Fault 3.8L (1 of 2)

Courtesy of GENERAL MOTORS CORP.