Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.

Scan tester displays transmission temperature in degrees Centigrade. After transmission is running, the displayed temperature should rise steadily to about 212°F (100°C) then stabilize. A faulty connection or an open in circuit No. 455/452 or circuit No. 1227 will result in a Code 59. Test the coolant sensor at various temperature levels to determine if sensor is out of calibration. See TRANSMISSION SENSOR - TEMPERATURE TO RESISTANCE chart. An out-of-calibration sensor could result in firm shifts, or TCC enabled complaint.

Fig 1: CODE 59, Schematic, Trans. Temp. Sensor Circuit Low

Courtesy of GENERAL MOTORS CORP.

Fig 2: CODE 59, Flow Chart, Trans. Temp Sensor Circuit Low

Courtesy of GENERAL MOTORS CORP.