February 2008 Archives

Among the many changes and improvements in the 2008 Cadillac CTS is a newly-designed radio and HVAC control module configuration known as the Integrated Center Stack (ICS) (fig. 1). The ICS system used in the CTS consists of three main components:

- the Radio/HVAC Control Assembly (or Infotainment Faceplate Control)

- the Radio

- the HVAC Control Module.

TIP: Inside General Motors, this Integrated Center Stack (ICS) is sometimes referred to as the "Silverbox" configuration (fig. 2).

RADIO/HVAC CONTROL ASSEMBLY

The Radio/HVAC Control Assembly is a separate component from the Radio and the HVAC Control Module (fig. 3). The Control Assembly contains the radio control knobs and buttons for all audio functions. In addition, the HVAC controls are part of the Control Assembly, including driver and passenger temperature control switches and heated or heated-vented seat, if so equipped

There are two basic Control Assembly designs with several button configurations depending on the vehicle options (XM radio, heated seat, heated and vented seat, and heated windshield washer).

- Non-navigation systems include a monochrome main display as part of the Control Assembly.

- Navigation systems do not include a main display as part of the Control Assembly. The display is separate and attaches to instrument panel together with the Display Module Actuator as an assembly (fig. 4).

TIP: As with current radios, if a replacement part is required, the Control Assembly part number can be retrieved using the Tech 2.

BASE AND UPLEVEL RADIOS

The Radio functions much the same as any conventional radio -- it receives the transmitted radio signal through the antenna, decodes the message the signal contains, amplifies this signal, then sends it to the speakers or remote amplifier. The radio receiver also processes information from recorded playback media (e.g., CD, MP3, DVD disc). All ICS radios are attached to the vehicle in a location similar to conventional radios.

The ICS radio system differs slightly from past radios. As always, the operator is able to control system power, volume, fade, balance, bass, and treble equalizations. The operator interfaces with the radio system through the buttons and control knobs located on the Control Assembly. Unlike past radios however, when the operator turns a knob or pushes a button, a module in the Control Assembly sends a signal to the Radio on a dedicated serial communications circuit.

TIP: This circuit is part of a wiring harness that connects the Control Assembly and Radio, but is not part of the other vehicle serial communication circuits.

HARD DISK DRIVE (HDD) AND NAVIGATION RADIOS

Some ICS Radios are now equipped with a hard disk drive (RPO U2S and UAV). These radios are able to record songs from Audio CDs, MP3 / WMA discs, and USB mass storage devices. The hard drive has a 40GB memory capacity. A portion of the HDD is used for the storage of radio system files and navigation map data on navigation radios. The remainder of the HDD capacity is available for the storage of media files.

Radios with HDD are able to play back audio-book content downloaded fromwww.audible.com. This content can be transferred into the HDD either by burning it to a CD or copying it to a USB storage device and then recording it to the HDD.

TIP: The audible.com playback requires activation of the vehicle as a player for the downloaded content. The radio system activates the audible.com system when information is found on either a CD inserted into the CD/DVD-A player or if a USB storage device is connected. The Vehicle Identification Number (VIN) number is required in order to activate the vehicle.

TIP: If the Radio needs to be replaced, the hard drive does not have to be cleared before sending the radio back to the Electronic Service Center. The scan tool can be used to clear the hard drive if desired.

AUXILIARY JACK/USB ADAPTER

An Aux jack/USB adapter is located in the rear of the center console bin (fig. 5).
The 3.5 mm auxiliary stereo jack is an input for analog signals, and the USB connector allows playback of digital audio media, from remote devices (e.g., laptop computer, iPod, MP3 player, etc.). When the Aux Jack and USB are used together with an iPod interface cable (p/n: 25908035), the Control Assembly controls can be used for iPod media file navigation.

HVAC CONTROL MODULE

The HVAC Control Module is a GMLAN device that interfaces with the HVAC air distribution system to maintain air temperature and distribution settings. This module is attached to the passenger hush panel below the glove compartment. As with the Radio, the operator interface dials and buttons for the HVAC Control Module are part of the Control Assembly. Button presses are communicated from the ICS to the Radio on the dedicated serial communication line. The Radio then communicates the information to the HVAC Control Module over GMLAN serial communications.

In a reverse manner, HVAC temperature selection, blower speed and other information is communicated to the Radio by the HVAC Control Module. The Radio then sends this information to the Control Assembly and the HVAC display areas are updated.

OTHER CONTROL ASSEMBLY INTERACTIONS

Heated and Vented Seats

Seat temperature requests are made with the buttons on the Control Assembly, and sent over the dedicated serial communication line to the Radio. The Radio places the request on GMLAN serial communications, which is received by the Memory Seat Module (MSM). As often as needed, the MSM sends seat temperature setting status to the Radio, and the Radio communicates with the Control Assembly and the seat displays are updated.

Passenger Presence Indicators

Passenger Presence System Air Bag On/Off indicator information is sent to the Radio from the Restraints system control modules over GMLAN serial data. The Radio communicates the information to the Control Assembly, which then turns on the correct indicator. Lighting intensity of these indicators is also controlled by the Control Assembly.

Hazard, Heated Windshield Washer and Traction

The Hazard, Heated Windshield Washer, and Traction buttons are not detected by the Control Assembly electronics and are not communicated to the Radio. These switches are wired directly to their respective modules. However, the Control Assembly does control backlighting of these switches.

- Thanks to Nohr Tillman and Steve Falko

This information applies to the 2007 Saturn Aura Hybrid with 2.4L Engine
(VIN 5 - RPO LAT).

On rare occasions, DTCs U0111 and U1897 may be experienced shortly after the BECM is reprogrammed. Typically, this occurs when performing service policy 07141 and reprogramming the BECM. This may occur if the vehicle required two BECM programming events, but only one BECM programming event was completed.

If DTCs U0111 and U1897 occur shortly after programming the BECM, review 07141 again and determine if two BECM programming events should have been performed.

If two programming events were required, the following two selections would have been displayed on the Supported Controller Screen of TIS 2 Web:

- BECM Hybrid Battery Voltage Correction

- BECM Hybrid Battery Software Enhancement

If both of these selections were displayed, but only one of them was completed, perform both BECM programming events as outlined in 07141 and re-evaluate the concern.

If both programming events were not necessary, or if this concern is still present after performing both programming events, perform the SI diagnostics for these DTCs and repair as necessary.

- Thanks to Jamie Parkhurst

On a 2003-08 Saab 9-3, the left side reverse lamp may not illuminate. There is no power to the circuit. There may be no change if the Rear Electrical Center (REC) is swapped.

The circuit for the left side reverse lamp is also tied into the rear view mirror auto-dim circuit. In the REC, connectors H2 pin 11 and T-C pin 1 are the same circuit, as they are jumped together internally. (See reverse lamp schematic.) This circuit supplies a signal to the rear view mirror to disable the auto-dim feature when backing up. If the REC sees any circuit shorted to ground, it will disable the circuit by removing the voltage for protection. The REC will continue to disable the circuit until the concern has been rectified. Verify the integrity of the circuit in question for shorting to ground. The rear view mirror may be improperly installed, trapping the wiring between the mirror and the body, pinching the wires and shorting the circuit to ground.

- Thanks to Jeff Gorenflo

This information applies to the clutch pedal position sensor (CPPS) used on the 2006-07 Pontiac G6 with manual transmission and all 2008 platforms with manual transmissions. A bulletin will be released to detail this important procedure.

The CPPS learn procedure must be performed to relearn the CPPS value for a depressed clutch after any of the following:

- ECM reprogramming

- ECM replacement

- Clutch pedal position sensor (CPPS) replacement

- Clutch pedal replacement

- Any procedure that alters the CPPS to clutch pedal alignment

WARNING: Replacement or reprogramming of the ECM or replacement of the clutch pedal position sensor (CPPS) or clutch pedal requires that a CPPS learn procedure be performed. Failure to perform the CPPS learn procedure may result in vehicle movement if the vehicle is in gear and the starter motor is accidentally engaged.

- Thanks to Bob Vandenbush and Ian MacEwen

The owners of some 2007 Terraza, Uplander, Montana or Relay models may comment of a rattle from the right side power sliding door while driving.

A protruding rivet on the outside of the interior latch assembly (fig. 6) can contact the door sheetmetal (fig. 7), causing a rattle type noise. To repair, install foam tape to the door sheetmetal to insulate the rivet.

- Thanks to Jeff Gorenflo

This information applies to the 2004-08 SRX, 2005-08 STS and 2006-08 CTS equipped with automatic transmissions.

Many automatic transmission shift control related concerns can be corrected with linkage adjustment.

DO NOT replace a shifter assembly without first attempting to correct the condition with the linkage adjustment procedure (fig. 8). Refer to SI for the proper service procedures.

A  Adjustment issues - forward biased

B  Adjustment issues - rearward biased

TIP: Symptoms of forward-biased adjustments (fig. 9) include cluster blanking out in Drive, and Tap Mode not functioning. Ensure that the linkage is adjusted properly when Drive blanks out, or Tap Mode does not function.

A Forward biased

C J-bracket

D Linkage

TIP: Symptoms of reverse-biased adjustments (fig. 10) include the inability to remove the key, or inability to exit Accessory Mode. Ensure that the linkage is adjusted properly when there is the inability to remove the key, or inability to exit Accessory Mode.

B Rearward biased

C J-bracket

D Linkage

TIP: When diagnosing a binding shift control system, disconnect the linkage from the shifter assembly and check the shifter assembly for smooth operation independently from the linkage. The transmission should be in Park during evaluation.

The linkage adjustment procedure is critical for proper transmission operation; therefore, several checks need to be performed after the linkage is adjusted:

- Inspect the operation of the starting system with the shift lever in each position. The engine should crank only when the lever is in the Park or Neutral position.

- Ensure that the feel of the shift detents align with the gear indicator.

- When in each gear, apply the button and release. Then slightly reposition the handle fore-and-aft in the vehicle. The button pawl will make a clicking noise if it is caught on a control mechanism gate. The button should not get caught up on the control mechanism gate in any gear. Readjust and retest if necessary.

- Return the lever to the Park position and check for proper engagement. Park position should feel solid and not spongy. The shift lever should not be bottomed out on the stop bumper when engaging the Park position. Readjust and retest if necessary.

- With the ignition on and the engine not running, ensure a smooth transition from position D to Tap Mode and back. Ensure that the DIC changes to the gear indicator mode. If the DIC does not change to gear indicator mode, or any binding or rough spots are felt, repeat the linkage adjustment procedure and retest the system.

If any of the following conditions exist after performing the linkage adjustment, the shifter may need to be replaced. Refer to bulletin 41276.

- The shifter binds when putting the vehicle into gear or Park

- The ignition key sticks or is hard to remove from the ignition lock cylinder (SRX only)

- The Shift to Park message is constantly displayed on the DIC when the shifter is in the Park position

- Dead battery

- The Tap Shift functions may experience a delay when operating the Tap-Up or Tap-Down mode

- The Tap Shift functions are inoperative

- The MIL/SES light is illuminated with one of the following DTCs:

- DTC P0815 - Upshift Switch Circuit

- DTC P0816 - Downshift Switch Circuit

- DTC P0826 - Up and Down Shift Switch Circuit

- DTC P1876 - Up and Down Shift Enable Switch Circuit Low Voltage

- Thanks to Ken Billette

Some owners of a 2008 CTS may comment that the Malfunction Indicator Lamp (MIL) and or Reduced Engine Power is displayed on the Driver Information Center. Further investigation may reveal one or more of the following DTCs are stored: P0087, P0089, P0451, P0452, P0628. The cause may be the engine wire harness chafing on the passenger front engine cover/sight shield ball stud bracket.

Inspect the engine wire harness breakout for the engine control module for chafing on the passenger front engine cover/sight shield ball stud bracket (fig. 11).

A Engine wire harness breakout

B Ball stud bracket

Repair the wiring as necessary. Reroute the harness under the battery negative cable away from the passenger front engine cover/sight shield ball stud bracket (fig. 12).

A Battery negative cable

B Ball stud bracket

- Thanks to Mike Ciarkowski

Here are some tips about lubricating the spare tire carrier hinge assembly on the Hummer H2. See SI document 1559969 and bulletin 08-03-10-001 for additional information.

IMPORTANT: Under normal conditions, the hinge assembly will NOT require lubrication.

TIP: There is a special grease for the carrier that should be used especially if the hinge is being lubricated because of poor cold weather performance. You must use special lubricant GM p/n 89022180 (Canadian p/n 89022181).

Remove the M6 set screw and the 1/4 inch plug (if equipped) above the set screw (fig. 13). Install a grease (zerk) fitting where the 1/4 inch plug was located. Some vehicles have the zerk fitting installed during assembly. Apply grease and rotate the swing arm to ensure a uniform coating over the internal bushing.

A Casting grease seal

B Zerk fitting

C Set screw

When the grease begins exiting the set screw hole, stop applying grease and reinstall the set screw. Tighten the set screw to 9 N·m (80 lb in).

Begin applying grease again, using the zerk fitting, and continue articulating the swing arm until grease is just visible on the casting grease seal.

TIP: DO not allow the swing arm to lift during lubrication. If the swing arm lifts, remove the set screw and apply downward pressure while rotating the swing arm. Continue until the swing arm makes contact with the casting.

The hinge is now primed with the correct amount of grease. Tighten the set screw to 9 N·m (80 lb in).

- Thanks to Larry Yaw

Some owners of a 2007-08 SRX may comment that the instrument panel (IP) upper trim panel has a gap to the IP (fig. 14). The cause may be insufficient friction between the retaining clip and the cut-out in the IP panel.

It is NOT necessary to replace the instrument panel upper trim panel. Apply one strip of 3M friction tape (p/n 03407NA) or cloth electrical tape to one side of the retaining clip opening(fig. 15). There are 6 openings that will need tape. After tape is applied, the effort needed to seat the clips is increased.

TIP: Do not use vinyl electrical tape, as it does not provide enough friction.

- Thanks to Michael Ciarkowski

This article first ran in the May 2006 issue of TechLink. Since that time, additional vehicles have been added, so here's updated information.

A number of GM vehicles are equipped with an OnStar Backup Battery (BUB) (fig. 16).

- Impala and Monte Carlo, 2006 and later

- Equinox and Torrent, 2007 and later

- Vue, Astra and G8, 2008 and later

TIP: Other vehicles may be added at a later date.

The BUB is a non-rechargeable, lithium battery with a lifespan of approximately 4 years and is designed to maintain an open circuit voltage between 16V and 9V throughout this period. This allows the battery to power the basic functions of the VCIM for least one 200-second (5 minute) phone call at the end of the 4 year span, should a main vehicle battery loss occur.

The BUB voltage is checked every ignition cycle. If the BUB fails the check or if the BUB has had current drawn from it, the OnStar LED next to the control buttons changes from green to red and a DTC is set, either B1446 or B1447.

Service Precaution

Do not disconnect the vehicle battery with the ignition key in the run position.

With the ignition key in the Run position, the OnStar module is awake on the data bus.
The OnStar module is also awake after the ignition key is removed, until Reserve Accessory Power (RAP) times out, or the driver door is opened. If the vehicle battery is disconnected with the OnStar module awake, the OnStar module senses a vehicle power failure, as could occur in a crash, and draws current from the BUB. When the vehicle battery is reconnected, the OnStar LED is red and a DTC is set. Because the BUB has had a current drain and there is no way of telling how long the drain was, the BUB must be replaced.

Refer to Accessories in SI for OnStar battery replacement information.

- Thanks to Howard Owens

On a 2000-05 Saturn L-Series, the horn may be inoperative, weak or muffled. The horn may have been replaced previously with an updated unit.

These conditions may be due to water intrusion. Install the updated horn in the alternate location indentified in the following procedure.

TIP: The updated horn is smaller and has a water deflector covering the opening.

1. If the horn has not been updated to the latest part, it will need to be changed to insure clearance in the new location.

2. Remove the horn and bracket from the inner fender (fig. 17).

3. Remove the grill.

4. Using the existing bracket, mount the horn to the underside of the top radiator core support on the driver's side (fig. 18).

5. Lengthen the wiring as needed to reach the new location. Use splice sleeves from the Terminal Repair Kit.

TIP: Be sure the horn does not contact the condenser or grill, and properly secure all wiring.

- Thanks to Jeff Gorenflo