Contents Wiring diagrams Section: Engine Controls - Tests W/codes - 4.3l All sections

CODE 87, HIGH GEAR RATIO ERROR - ALL MODELS Chevrolet Astro I

CODE 87, HIGH GEAR RATIO ERROR - ALL MODELS

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

  1. An out-of-calibration transmission range pressure switch could falsely indicate actual transmission range.
  2. This test verifies proper ratio.

Check all connections, especially those at transmission pass-thru connector. Fault may be an internal transmission problem.

Code 87 Flow Chart (4.3L) High Gear Ratio Error. Scheme 205

Scheme 205: Code 87 Flow Chart (4.3L) High Gear Ratio Error