CVT - Squealing Sound On Light Acceleration

NUMBER: 16-85-12R
DATE: 11/26/12
REVISED: 12/12/12

APPLICABILITY:
2010-2012MY Legacy and Outback Models
with CVT

SUBJECT:
CVT Secondary Pressure Sensor Diagnostics

INTRODUCTION

This Bulletin provides an inspection and diagnosis method for the CVT's secondary pressure sensor which if failed, could create a customer concern of a squealing-type sound during light throttle application. The Service Manual will be revised in the future with this information.

SERVICE PROCEDURE / INFORMATION

^ Road test the vehicle to confirm the condition and bring the transmission up to normal operating temperature.

^ Turn off the ignition and allow the vehicle to sit at least 10 minutes while preparing the SSMIII and gaining access to the Transmission Control Module (TCM) main wiring harness connector. This will allow the secondary pressure sensor sufficient time to fully drain off any
residual fluid pressure.

^ After connecting the SSMIII, confirm the CVT's fluid temperature is between 10° and 80°C (50°- 176°F). NOTE: DO NOT start the engine at any time while performing the following voltage checks.

^ Perform the following voltage checks on the TCM connector, B54:

1. With the ignition switch on and engine off, check the voltage between pin # 2 (power supply) and #15 (ground). Specified value is 4.8v to 5.2v. If the voltages are outside of the specified range, the TCM is damaged along with the pulley surfaces of the CVT due to chain slippage. Replace both the TCM and the CVT assembly.

*IMPORTANT:
Although both the TCM and CVT assembly may need to be replaced, the testing outlined in steps 2 and 3 below MUST be completed and your results recorded.*

2. With the ignition switch on and engine off, check the voltage between pin # 17 (pressure sensor output voltage) and # 15 (ground). Specified value is 0.45v to 0.55v. If the voltages are outside of the specified range, the secondary pressure sensor is damaged along with the pulley surfaces of the CVT due to chain slippage. Replace the CVT assembly.





3. IMPORTANT:
Before ordering a new TCM and / or CVT, perform these same voltage checks at the secondary pressure sensor connector (AT6) and (if necessary), the main transmission harness connectors (T4 and B11). Ruling out wiring issues will prevent repeat or unnecessary component replacements.

REMINDER:
Whenever replacing the CVT assembly, TCM, control valve body or servicing the CVT fluid, the Learning Control procedure must be completed.

WARRANTY / CLAIM INFORMATION





For vehicles within the Basic New Car Limited Warranty period, this repair may be claimed using the information shown.





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