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All Info About Auto Repair: Diagnose Automatic Transmission Problems Part 2
All Info About Auto Repairs
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Diagnose Automatic Transmission Problems Part 2

What you can do to diagnose an automatic transmission problem.
» Engine/Transmission Relations
» Transmission or Transaxle?
» Transmission Testing
» Transmission Leak Tests
» Diagnosis By Symptom


Basically a transaxle is a fully automatic electronically controlled front wheel drive transaxle with four forward gear ranges including overdrive and one reverse gear range. A variable displacement vane type oil pump supplies oil pressure. Two shift solenoids, operated by the Powertrain Control Module (PCM), control shift points and TCC apply rates, which are influenced by various sensor inputs. The transaxle unit includes a three element hydraulic torque converter and lockup clutching element, four multiple disc clutch packs, roller clutch, sprag clutch, two bands and a compound reaction planetary gearset. Power is transmitted to the drive wheels from the planetary gear through a final drive gearset and differential assembly.


The normal automatic transmission is fully automatic with four forward and one reverse speed. It consists of a lockup torque converter assembly and a three unit planetary gear train. Electronic controls for the transmission are integrated into the on-board Powertrain Management systems. Sensors provide inputs to the Powertrain Control Module (PCM). The PCM electronically controls the transmission hydraulic system for gear selection and automatic shift control. Torque converter operation is controlled by the PCM. These controls, along with hydraulic controls in the main control body, operate a piston plate clutch in the torque converter that eliminates torque converter slip when applied.


There are several ways to test an automatic transmission. There are some that can only be done by a shop that has the proper equipment, and others you can do at home.

» Part 1       » Part 2       » Part 3       » Part 4
» Part 5
Additional Information provided courtesy of
ALLDATAdiy.com and Warranty Direct
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