LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1997 >> Forward Control 6.5 F >> Repair and Diagnosis >> External Pages >> Different car >> Section 45 (Engine Controls - Tests W/Codes - 7.4L) >> Trouble Code Charts >> Code 86, Low Gear Ratio Error >> Notes
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Code 86, Low Gear Ratio Error: Notes

WARNING: This page does not describe the selected car, but rather 18 other vehicles, including the 1995 GMC Vandura Special, 1995 GMC Vandura, 1995 GMC Suburban, 1995 GMC Rally Camper Special, and 1995 GMC Rally. However, it is still accessible from the selected car via links, so may be relevant.

Control module calculates ratio based on transmission input speed and output speed sensor readings. Control module compares known ratio to calculated ratio.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. An out-of-calibration transmission range pressure switch could falsely indicate actual transmission range.
  2. This test verifies proper ratio.
scientia non olet · About LEMON Manuals