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AUTO TRANS DIAGNOSIS - 01M
Article Text (p. 4)
1996 Volkswagen Golf
For Volkswagen Technical Site
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, August 19, 1999 11:28PM
engaged depending on engine load and vehicle speed.
Power from the transmission is connected to the drive pinion
through transfer gears. A ring gear and differential assembly are
connected to flanges which spin the drive axles.
The electronic control consists of a TCM (located under rear
seat), control solenoids, various sensors and switches. The control
solenoids direct oil pressure inside the valve body. Solenoid valves
No. 1-4 control the apply and brake clutches. Solenoid valves No. 5
and 7 control shift smoothness. Solenoid valve No. 6 is a frequency
valve and controls the main hydraulic pressure. The TCM controls the
main hydraulic pressure by varying the duty cycle.
The TCM monitors input and output signals. If electrical
problems occur, TCM will record faults in TCM memory and may go into
fail-safe mode (also known as emergency running mode). If TCM enters
fail-safe mode, the transaxle will operate manually in reverse, 1st or
3rd gear. In fail-safe mode, 3rd gear operates with gear selector in
2nd, 3rd or "D". If engine is started with TCM in fail-safe mode, TCM
activates 3rd gear hydraulically. The TCM memory can only be read
using Scan Tool (VAG 1551) and Adapter (VAG 1551/3).
The TCM also controls shift lock system. This system locks
the gear selector in Park or Neutral position unless the brake pedal
is pressed. The TCM uses a shift lock control relay to release a gear-
selector mounted solenoid. See Fig. 2.
Fig. 3: View Of Transaxle Clutch Elements
Courtesy of Volkswagen United States, Inc.