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Home >> GMC >> 1991 >> Forward Control 7.4 N >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Transmission >> Trouble Code Charts >> Code 86, Shift Solenoid "B" Stuck "On" >> Notes
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Code 86, Shift Solenoid "B" Stuck "On": Notes

The shift solenoids are used inside the valve body to control spool valves, which determine the transmission gear. Fused ignition power is supplied to solenoid "B". The PCM/TCM will engage solenoid "B" by grounding circuit No. 1223 to energize the solenoid.

Code 86 will set under the following conditions.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This test determines if transmission is receiving a solenoid "B" on command.