A/T - VT25E Launch Hesitation
Bulletin No.: 05-07-30-003Date: January 24, 2005
TECHNICAL
Subject:
Intermittent Hesitation During Vehicle Launch (Replace Transaxle Input/Output Sensors or Transaxle Case Cover Assembly, If Necessary)
Models:
2002-2005 VUE
2003-2004 ION
with VT25E Vti Transaxle (RPO M16/M75)
Attention:
Technician
Condition
Important:
This bulletin is for the intermittent hesitation condition only and is not intended to repair a no movement condition.
Important:
Procedures outlined in this bulletin are intended to address customer concerns with 2002-2005 Saturn VUE vehicles equipped with the VT25-E Vti transaxle that still experience the intermittent hesitation condition after performing Bulletin 03-07-30-051A.
Some customers may comment on an intermittent hesitation that occurs during vehicle launch from a stopped position.
Cause
There may be two potential causes for the intermittent hesitation condition.
Cause 1:
A condition may exist in which the transmission speed sensor may inadvertently become unstable. This is caused by miscommunication between the input and output speed signal in the transmission assembly. This may cause a speed sensor abnormality during initial vehicle launch resulting in an intermittent hesitation.
Cause 2:
The transaxle may have an internal pulley leak resulting in a lack of clutch apply "clamping force" on the belt/pulley system. This may result in a customer concern of intermittent hesitation during vehicle launch below an engine speed of 1800 RPM.
Correction
Determine if the condition is caused by an internal transaxle leak using the "Line Pressure Check" procedure outlined in this bulletin.
Line Pressure Check Procedure
Tools required
J45195 Line Pressure Gauge
Caution:
Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.
1. Remove the fluid pressure test hole plug from the transaxle.
Important:
Permatex(R) High Temperature Thread Sealant, P/N 21485278 (GM P/N 12346004, in Canada P/N 10953480) or equivalent, must be applied to the threaded components of the pressure gauge to ensure that no leakage occurs during testing.
2. Ensure the gear selector is in PARK and the parking brake is set.
3. Install the line pressure gauge (J45195).
4. Install a scan tool.
5. Start the engine and allow the engine to warm up to normal operating temperature (170° - 185°F).
6. Access the Line PC Solenoid functional test on the scan tool output controls.
Note:
The total test running time should not be longer than 2 minutes. Running the test longer than 2 minutes may damage the transaxle.
Important:
The scan tool can only control the line pressure control solenoid when the transaxle is in "P" (PARK) and the engine is running. This protects the transaxle clutches from extremely high or low pressure, as when the transaxle is in "D" (DRIVE) or "R" (REVERSE).
7. With the engine speed at idle, use the scan tool to increase the Line PC Solenoid amperage to 1 amp. Read and record the corresponding line pressure on the pressure gauge.
Important:
In order to obtain the required pressure for the high-pressure test point, the engine speed must be 1400-1500 RPM. A line pressure reading taken at a lower engine speed will be inaccurate and may lead to misdiagnosis.
8. Slowly increase the engine speed to 1400-1500 RPM before performing the next test step.
9. Using the scan tool, decrease the Line PC Solenoid amperage to 0.2 amp. Read and record the corresponding line pressure on the pressure gauge.
10. Shut the engine OFF. Remove the line pressure gauge.
Important:
Before installing the fluid pressure test hole plug, apply Permatex(R) Medium Grade Threadlocker Blue, P/N 12345382 (in Canada, P/N 10953489), or equivalent, to the threads of the plug.
11. Install the fluid pressure test hole plug.
12. Tighten the plug.
Tighten
Tighten the fluid pressure test hole plug to 9 Nm (80 in-lbs).
13. If the pressure reading recorded in step 7 is below 246 psi (1696 kpa), replace the following:
^ Case Cover Assembly (Refer to the "Case Cover Assembly Removal and Installation" procedures located in the appropriate Saturn Service Manual.)
^ Control Valve Body Assembly (Refer to the "Control Valve Body Replacement" procedures in the appropriate Saturn Service Manual.)
^ Oil Cooler Lines (Refer to the "Oil Cooler Line Replacement", procedures in the appropriate Saturn Service Manual.)
14. If the pressure reading recorded in step 9 is below 600 psi (4137 kpa), replace the following:
^ Case Cover Assembly (Refer to the "Case Cover Assembly Removal and Installation" procedures located in the appropriate Saturn Service Manual.)
^ Control Valve Body Assembly (Refer to the "Control Valve Body Replacement" procedures in the appropriate Saturn Service Manual.)
^ Oil Cooler Lines (Refer to the "Oil Cooler Line Replacement" procedures in the appropriate Saturn Service Manual.)
15. If line pressures are within an acceptable range (above 246 psi in step 7 or 600 psi and above in step 9), replace the Transaxle Input and Output Speed Sensors with the newer design sensor, P/N 24229640. (Refer to the "Input and Output Speed Sensor Assembly Replacement" procedure located in the appropriate Saturn Service Manual.)
The newer design speed sensors have an integrated bi-directional zener diode, which protects the circuits from spikes or erratic abnormalities affecting sensor feedback to the Transmission Control Module (TCM).
Parts Information
Claim Information
To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System for K7104 (Cover Assembly, Variable Drive and Driven Pulley Assemblies, Belt and Case - Replace) or K6310 (Sensor, Transaxle Speed - Replace). Add Times have been included, to perform a line pressure test and replace oil cooler lines, for both of these labor operations.
Retail Reimbursement
One container of Liquid Polyacrylate (PA) Sealant, P/N 24233365, can perform 11-13 vehicle repairs outlined in this bulletin. Permatex(R) High Temperature Thread Sealant, P/N 21485278, can perform 20-25 vehicle repairs outlined in this bulletin.
Disclaimer