For 1990-2009 cars

# 4L60-E/4l65-E Automatic Transmission Diagnostic Information on Harsh 1-2 Upshift

Subject: | 4L60-E/4L65-E Automatic Transmission Diagnostic Information on Harsh 1-2 Upshift

Models: | 2001-2006 GM Passenger Cars and Light Duty Trucks

| 2003-2006 HUMMER H2

| 2006 HUMMER H3

| 2005-2006 Saab 9-7X

| with 4L60-E or 4L65-E Automatic Transmission

This bulletin is being revised to add model years and models. Please discard Corporate Bulletin Number 01-07-30-030A (Section 07 - Transmission/Transaxle).

The following four conditions have been found to cause the majority of consistent, harsh 1-2 shift comments.

• | Chips/Sediment/Debris/Contamination found in the valve body, 1-2 accumulator valve (371) bore, may cause the 1-2 accumulator valve to stick or hang-up.

• | Chips/Sediment/Debris/Contamination found in the valve body, 4-3 sequence valve (383) bore, may cause the 4-3 sequence valve to stick or hang-up.

• | A cracked 1-2 accumulator piston (56) that is allowing fluid to leak by.

• | Mislocated/Missing valve body-to-spacer plate check balls (61).

When attempting to correct a consistent harsh 1-2 shift, the four conditions listed above should be inspected as possible causes. It is important to also refer to the appropriate Service Manual for further possible causes of this condition.

#### Slipping or Rough 1-2 Shift

Checks | Causes
--- | ---
Valve Body Assembly |

• | Mislocated valve body to spacer plate checkball or checkballs.

• | 1-2 Shift valve train stuck due to sediment

• | Gaskets or spacer plate incorrect, mispositioned or damaged

• | 1-2 Accumulator valve stuck or damaged

• | Face not flat

• | 4-3 sequence valve stuck or damaged

• | #1 or #8 checkball missing or mis-located

• | 1-2 accumulator valve bushing rotated 180°

2-4 Servo Assembly |

• | Apply pin too long or too short

• | 2nd servo apply piston seal missing, cut or damaged

• | Restricted or missing oil passages

• | Servo bore in case damaged

2nd Accumulator |

• | A cracked 1-2 accumulator piston - allowing fluid to leak by

• | Porosity in 1-2 accumulator cover or piston

• | Piston seal or groove damaged

• | Nicks or burrs in 1-2 accumulator housing

• | Missing or restricted oil passage

• | 1-2 accumulator piston spring not seated

• | Rough finish in 1-2 accumulator bore in case

2-4 Band | Worn or mispositioned
Oil Pump Assembly or Case | Faces not flat

This diagnostic table should be used when addressing a harsh 1-2 shift concern (SI Document ID 10224).