Code 87, High Gear Ratio: Notes

The shift solenoids are used inside the valve body to control spool valve position, which determines the transmission gear.

Fused ignition power is supplied to solenoid "B", also referred to as 2-3 shift solenoid. PCM/TCM engages solenoid "B" by grounding circuit No. 1223.

Code 87 will set under the following conditions.

• Vehicle speed is greater than 7 MPH.
• TPS is more than 25 percent.
• PCM/TCM commands 3rd or 4th gear.
• Transmission ratio indicates transmission is in 1st or 2nd gear.
• Conditions are met for 6 seconds.
  NOTE: Test numbers refer to numbers on diagnostic chart.

1. This test checks PCM/TCM's ability to ground or control solenoid "B". If bidirectional scan tester is not available, solenoid may be activated by grounding ALDL test terminal "B" with ignition on and engine off.
2. This test checks the power supply and circuit No. 1223.
3. This test checks the internal transmission harness and solenoid "B".