Programming instructions

6 December 2013
Rear Brake Noise on
First Apply
Power Liftgate
Inoperative with
Key Off
On some 2013 Encore AWD and Trax AWD (Canada
only) models, after the vehicle is first started, a rear
brake noise may occur during the first time the brakes are
applied when backing up. The noise also may occur the
first time the brakes are applied with the vehicle in Drive.
The vehicle may have been sitting only a few hours or
overnight.
To eliminate the nosie, install a dampener (P/N
13343688) and bolt (P/N 13343686) in place of the rear
upper caliper mounting bolts. Refer to the appropriate
Service Information (the Brakes section under Rear Disc
Brake Pads Replacement) for bolt removal instructions
and the proper torque specification.
Thanks to Matthew Zajechowski
The power liftgate may be inoperative on some 2007-
2014 Escalade models, Suburban, Tahoe and Yukon
models when using any of the switches or the Remote
Keyless Entry transmitter with the ignition in the OFF
position. If the ignition is in the Accessory or the ON
position, the liftgate will operate correctly.
To correct this condition, check for power on the Acces-
sory Wake Up Data Line going to the ECM and the TCM.
With the key in the Accessory position, check for battery
voltage on circuit 5985 going to pin 18 (2007 and 2010-
2014 model years) or to pin 31 (2008-2009 model years)
of connector 1 to the ECM and Pin 11 (RPO MT1 trans-
mission) or Pin 9 (RPO MYC transmission) to the TCM.
If no voltage is present with the key in the accessory
position, check for a wiring or pin fit concern.
Thanks to Scott Fibranz
Corvette Tire Chatter
Rear upper caliper mounting bolt
The Corvette always has been built to perform. Part of the ride and
handling equation is the high-performance tires available on recent
Corvettes.
The 2014 Corvette is equipped with standard P245/40ZR18 front
and P285/35ZR19 rear performance summer-only tires and the Z51
Performance Package includes P245/35ZR19 front and P285/30ZR20
rear Michelin Pilot Super Sport ZP summer-only tires. These tires may
have a chatter noise during
low speed turns.
The tread design of the
Goodyear F1 tires on the
2011-2013 Corvette Grand
Sport and Z06 models also
is more susceptible to tire
chatter or hop than the
tread design on previous
F1 tires.
Tire chatter noise, caused
by the large amount of tire
scrubbing across the pave-
ment, occurs most often
during low speed, tight
turns (in all directions)
when the tires are cool,
usually after an extensive ambient soak of the vehicle. The chatter
typically diminishes when the tires warm up, but may increase on wet
pavement. This is a normal characteristic of the high-performance tires.
It’s important not to confuse a tire chatter condition with a possible
rear differential chatter noise.
A vehicle soak of at least eight hours during cool ambient temperatures
is required prior to evaluation on a clean, dry asphalt or concrete road
surface. There should be sufficient space for two to three full vehicle
turns at idle speed. Limit the evaluation to no more than four full
vehicle circles.
To evaluate the noise condition:
1. With the engine running and the vehicle at rest, turn the steering wheel
until full steering lock is achieved.
2. Shift into gear. The noise should be heard once the vehicle has made
one to two circles.
3. With the vehicle moving in a tight circle and the noise present, move
the steering wheel in 1/4 turn increments away from the full lock posi-
tion. A maximum of 1/2 to 3/4 turn should be sufficient to determine
the source of the noise.
4. Place a hand at the 6 o’clock position as a reference indicating full lock.
Move the steering wheel to the 3 or 9 o’clock position and hold it for
two to three seconds. Repeat if necessary for a maximum of four com-
plete vehicle circles.
If the noise is caused by front tire hop, it will reduce in severity or
cease during the turning sequence as soon as the steering wheel is
turned. A 1/4 steering turn will usually dramatically reduce front tire
chatter.
If the noise is caused by rear differential chatter, it will not be reduced
in severity when turning the steering wheel, but may be reduced in
frequency. If the differential is the cause of the noise, refer to Rear
Drive Axle in the appropriate Service Information.
For additional information, refer to Bulletin #09-04-20-001D and to the
May 2010 Emerging Issues seminar, course number 10210.05.
Thanks to Jeremy Richardson and Art Spong