Install Guide - 4L80E - GM (Automatic Transmission)



• Scan vehicle for engine and transmission codes, record all codes, and resolve all engine codes prior to transmission replacement
• Compare replacement transmission and torque convertor to original before installation
• Hot flush or replace the transmission cooler and lines
• Inspect the flex plate for cracks or damage – replace if necessary
• Inspect the crank pilot bore for wear and apply grease to bore to aid installation
• Install supplied tail shaft housing gaskets and seals as applicable
• Inspect engine and transmission mounts, driveshaft(s), yoke(s), and U-joints
• Verify both dowel pins are present, clean, and in good condition
• Check torque converter bolts for proper length
• Verify torque converter is properly and completely installed onto transmission input shaft
• Do not tighten bell housing bolts with force; torque converter may have shifted during installation
• Inspect and install PRNDL Neutral Safety Switch
• Fill transmission with purchased synthetic fluid or Dexron III/IV



Entire transmission cooling system must be completely cleaned, hot flushed, and flow tested.

A restricted and/or contaminated transmission cooling system is the #1 cause of transmission failure. If the cooler is plugged, it must be replaced.

This is an electronically-controlled transmission. The following information is VERY important to understand and to perform correctly. Failure to do so may damage your new transmission and/or cause performance problems:

  • Verify proper function of the entire electrical system including the battery, alternator, vehicle grounds, mass air flow sensor, and throttle position sensor.
  • Inspect transmission wiring harness for damaged wires or connectors.
  • Reset the adaptive memory with a scan tool before operating new transmission for the first time; disconnecting the battery is not sufficient.
  • A final system scan is required after the road test or if problems are detected during the road test. If codes are still present, compare to original code scan recorded prior to transmission replacement.

Applicable Models:

  • 1991–2013 Chevrolet C/K/Chevrolet Silverado/GMC Sierra V8
  • 1991–2013 Chevrolet Suburban/GMC Yukon
  • 1995–2003 Chevrolet Tahoe/GMC Yukon
  • 1991–1996 Chevrolet Van/Chevrolet Express/GMC Savana
  • 2002–2006 Chevrolet Avalanche V8 8.1L
  • 1992-2006 Hummer H1
  • 1992–1998 Rolls-Royce Silver Spirit/Spur II, III, IV
  • 1991–1992 Bentley Eight
  • 1991–1997 Bentley Turbo R
  • 1991–2002 Bentley Continental R/S/T
  • 1999–2006 Bentley Arnage Red Label / Bentley Arnage R/RL/T
  • 1993–1996 Jaguar XJS
  • 1994–1997 Jaguar XJR
  • 1993–1997 Jaguar XJ12 / Daimler Double Six
  • 1996–1999 Aston Martin DB7
  • 2000- 2006 Chevrolet HD Trucks
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