Code 86, Shift Solenoid "B" Stuck "On" - LT. Truck: 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. See Figure.

Code 86 will set under the following conditions:

• Vehicle speed is greater than 7 MPH.
• TPS is more than 25 percent.
• PCM/TCM commands 1st or 2nd gear.
• Transmission ratio indicates transmission is in 3rd or 4th gear.
• Conditions are met or 6 seconds.
  NOTE: Test number refers to test number on diagnostic chart.
  1. This test determines if transmission is receiving a solenoid "B" on command.