A/T - Computer Diagnosis: Overview
TRANSMISSION: SprintBULLETIN: # 023
SUBJECT: Computer Diagnosis
DATE: September 1990
ELECTRICAL DIAGNOSIS OF THE CHEVY SPRINT
The Chevy Sprint and Geo Metro are computer shifted transaxles. The basic operation of the system is similar to other computer shifted transmissions.
The most common calls we receive are on diagnosing a no upshift condition or wrong gear starts. The first procedure to follow when the transaxle will not shift properly, is to disconnect the solenoid wires. The transaxle now should act as if it has a manual valve body. "D" range will be third gear, "2" range will be second and "L" range will be first.
Perform a road test to see if the transaxle will manually upshift with the wires disconnected. If the transaxle will not upshift, check the valve body. You could have stuck shift valves or defective solenoids. If the transaxle operates manually with the wires off, but not with the solenoids connected, you probably have a defective electronic control system.
FOR ADDITIONAL INFORMATION
Trans Digest:
August 90 June 69
ATRA: TSB 87-60
BULLETIN RECAP
^ Unplug the wires and manually shift the transaxle.
^ Bypass the computer by providing your own signals with two 12 volt wires.
^ Check the various switches with a volt-ohm-meter.