June 2007 Archives

Multiple Diagnostic Interface Watch for It

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The GM Multiple Diagnostic Interface (MDI) EL-47955 is being shipped to NAO dealers the third quarter of 2007, one per dealer. (fig. 1)


The January 2007 issue of TechLink introduced you to the new GM MDI. It is a compact communication module that manages the transfer of data between a vehicle's onboard ECU network and a PC. When software coverage on the GM MDI is fully operational, all diagnostic and reprogramming for GM vehicles globally will be supported with this one piece of hardware.

TIP: Additional tools can be ordered by calling 1.800.GMTOOLS (1.800.468.6657), using prompts 1 or 4.


The EL-47955 GM MDI is a kit of components (fig. 2):



B   J1962 Diagnostic connector

C   USB cable

D   Ethernet cable

E   AC adapter/power supply

      Wireless interface

      AAA batteries

      Owner manual

The initial operating software for the MDI is included on a CD. Future updates will come from the TIS2Web application.


Beginning with the 2008 model year vehicles, Pass-Thru will be the only programming method available. (Remote will continue to be available for previous vehicles.)

The new GM MDI can be used only in the Pass-Thru method. This means you can use it as your programming tool, while your Tech 2/CANdi remains available for diagnostics and other duties.

The GM MDI is initially being introduced with Pass-Thru programming capabilities only. It can be used to perform Pass-Thru programming on all vehicles built since 1996 and will support all vehicles into the future.

The GM MDI will be required to perform diagnostics on selected NAO vehicles for model year 2009. Diagnostic software is scheduled to be released for the GM MDI during the fourth quarter of 2008.

Regulations require programming procedures to be compliant with SAE Recommended Practice J2534. The GM SPS is compliant with SAE Recommended Practice J2534, and the GM MDI is compliant with the portions of SAE J2534 that are applicable for GM vehicles.


For immediate use -- At present, vehicles have two buses on the 16 pin connector
(high speed and low speed GMLAN). The GM MDI communicates using all of the existing GM protocols, the same as the Tech 2:


- Class 2

- KWP2000


For future use -- Global architecture coming in July 2008 for MY 2009 will use a total of 4 GMLAN links. (This is a limited rollout in MY 2009.) Global architecture adds a medium speed bus and an expansion bus. The Tech 2 and CANdi module can run only low and high speed, and won't work on the 4 GMLAN link system for diagnostics or programming. The MDI will have this capability.


There are three ways to connect your GM MDI to the PC (fig. 3) that will be delivering your reprogramming events. They are:


A   Mini USB connector

B   Ethernet connector

1. USB version 1.1/2.0

- Connected directly to your PC or laptop for first-time setup

- Advanced configuring

- Updating MDI software

- Programming or future diagnostics

TIP: Any PC can be used, so long as it meets the PC Hardware Specification located at this link: http://www.gmde.net/standards.cfm.

IMPORTANT: If you choose one of the following two advanced connection methods, refer the task to your dealership's IT specialist.

2. Wired Ethernet 10/100/1000

- Connected to the service LAN for programming or future diagnostics

3. Wireless Ethernet 802.11 B/G

- Connected to the service LAN for programming or future diagnostics

You will use the USB connection as the initial connection to set up your MDI and to configure the other two optional connections. You can also reprogram with this connection.

Deciding Which Connection to Use

The USB connection is limited to about 10 feet of cable. To obtain a greater distance from the PC to the MDI, you will need to use wired Ethernet or wireless Ethernet. If you don't have a wireless access point in your shop, you will probably use the wired version.

In order to use these other options, some additional equipment may need to be obtained.

To use wired Ethernet, you will need:

1. Cat 5e or Cat 6 Ethernet cables

2. An open RJ45 port that connects to the service LAN


3. An unmanaged switch (see table)

4. Additional IP addresses from your Dealer Management Service if they are required. (This may be required for static IPs only.)

The unmanaged switch must be placed in a location with convenient access to a plug and the MDI Ethernet cable. Your shop may already have such a device and all you need to do
is plug into it. This switch must be on the same network as your MPI PC or your service network. This is where your programming information will come from.

To use a wireless access point, you will need:

1. Wireless access point (see table)

2. Cat 5e or Cat 6 Ethernet cables

3. Additional IP addresses from your Dealer Management Service if they are required.
(This may be required for static IPs only.)

Feedback Sharing Your Comments with Techline

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The Techline team appreciates when users take a moment to share with us their feedback regarding our websites. Our goal is to quickly provide GM technicians the information they need to service our vehicles.

The following provides an overview for submitting feedback to Techline regarding these applications.

- Service Information (SI), including the Service Manual, Bulletins/Campaigns, and the GM Labor Time Guide.

- TIS2WEB, including Tech 2 Diagnostics and the Service Programming System (SPS).

Your feedback helps us keep the applications working properly, helps ensure that the applications are user-friendly, and helps ensure that the information provided is accurate.

To get started, you must first select SI or TIS2WEB from the GM DealerWorld home page (GM infoNET in Canada).

TIP: If you wish to provide feedback about the DealerWorld site, use the feedback button located at the top right of the main page.

Service Information (SI)

TIP: SI is now available in both English and Spanish.

There are several ways to access the SI feedback form. Depending on where the form is accessed from, the form will be sent to one of three mailboxes for review and response. The three mailboxes are Service Manual, Labor Time Guide, and Bulletins/Campaigns.

First, on the SI home page, you can click on the Feedback link (fifth icon on the list) (fig. 4). From this page, the form will automatically default to the Service Manual mailbox.


Second, on every service document in SI, there is a Feedback button in the upper right corner (fig. 5). Click on this button to open the Feedback form.


Once the feedback form is open, fill in all of the relevant blanks, including your name, dealer name, dealer code, etc.

TIP: Be sure to include your email address and phone number, because someone from the SI team may want to contact you for further discussion.

To submit a problem, fill in the requested information. Be as thorough as you can be when giving a detailed description of the problem.

TIP: If you have already "built" a vehicle, and are looking at a service document when you click the Feedback button, the feedback form will automatically fill in the vehicle you're working on and the document ID number.

To submit a suggestion, fill in the box provided, using your own words to give a detailed description of your suggestion.

Once you have submitted your feedback, SI will send an automated receipt to let you know it has been received.


To open the TIS2WEB feedback form, click on the Feedback icon in the toolbar. It's the second icon from the top right of the page.

You can choose the type of feedback you wish to comment on, using the pulldown menu in the upper left corner of the page.

The Online Questionnaire is the default form, and is the one you'll probably use the most.

Fill in the spaces provided to comment on the content of the website, the timing of the content (is it on time to help your customer?) and your overall satisfaction.

To provide specific comments or to offer specific critiques, use the comment box provided. Type your comments into the box in your own words. Be as thorough as you can, and provide as much detail as possible.

It's recommended, but optional, that you fill in the contact information at the bottom of the form. This is necessary if you want to receive a response. Your response will be sent to you by email. Typically, allow 30 days or less for a response if your issue is "mainstream." Allow more time if your issue will require extensive research.

- Thanks to Lisa Scott and Mike Waszczenko

Programming Tip Module Reconfiguration

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Has this ever happened to you? After programming a module, certain features don't work. This could apply to any vehicle module, but particularly modules on the low speed GMLAN bus.

The last step of programming is to turn off the ignition key to remove power from the module. When the module is powered-down, it "reboots," which allows reconfiguration to take place.

On vehicles with retained accessory power (RAP), simply turning the ignition off is not sufficient. RAP continues to supply power to many circuits for up to 10 minutes.

You need to turn the ignition off, open the driver door, then close the door. RAP is now disabled, ignition is off, and the module can reconfigure.

- Thanks to Mark Stesney

Seatback Removal

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These tips show how to remove the seatback on the new fullsize utilities. The retainers
(fig. 6) are very robust, and can be disengaged without damage, following these steps.

Top tab (fig. 7)

Side retainer (fig. 8)


Lower tab (fig. 9)


1. On the right and left sides of the upper portion of the seatback, insert a flat bladed tool (trim stick) between the seatback and the seat cushion to release the retainer tabs (fig. 10). Push the tool against the tabs to release.


TIP: There is no need to pry on the seatback with the tool.

2. Carefully flex the seatback outward to slide the top tabs out of the retainer slots (fig. 11).


3. On right and left sides of the lower portion of the seatback (fig. 12), insert a flat bladed tool between the seatback and the seat cushion to release the retainer tabs.


4. Carefully pull back on the seatback. All released tabs must be clear of obstructions.

5. On the right side of the seatback, place your fingertips underneath the seatback. Apply a small force inward with your palm to release the tab (fig. 13). Carefully lift up the right side of the seatback.


6. On the left side of the seatback, place your fingertips underneath the seatback. Apply a small force inward with your palm to release the tab. Carefully lift up the left side of the seatback.

- Thanks to Adam Freeman and Dave Roland

VME Ends

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GM Service Voice Mail Express (VME) ends on June 1, 2007. When Service VME launched in 2000, it was the quickest way to get service information to dealers. With the present capability to update service information in SI and DealerWorld daily, we are now able to quickly send a GM Messenger Message, and it can be printed or forwarded. Service VME messages will transition into GM Messenger Messages under the Functional Role: Service Manager.

TIP: Please continue to submit Field Product Reports using the process outlined in Bulletin 02-00-89-002F. Field Product Reports are extremely important to the product problem resolution process.

- Thanks to Ron Caponey

Panoramic Sunroof Update

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A recent bulletin 05-08-67-014 update provides general guidelines to noise issues with the panoramic sunroof in the Pontiac G6 (fig. 14). Here are highlights of two of the conditions described in the bulletin.


US dealers, also refer to Tech Assist course 50250.17T1 Multi-Panel Panoramic Roof Adjustments for more information.

Creak/Snap/Pop Noise

This condition occurs while driving over bumps and comes from the sunroof module, and is usually caused by roof interaction with the fasteners.

TIP: The bulletin specifies slightly different repairs depending on whether the vehicle was built before or after January 1, 2006, when mylar washers were added to production.
For vehicles without the washers, the bulletin explains how to install them.

For all vehicles, lubricate the 10 locations of the mylar washers using GM Super Lube
(p/n 12346241) (fig. 15).


TIP: Use Super Lube only. No fastener adjustments are necessary unless noise is still present after lubrication.

TIP: It is necessary to lower the headliner before spraying the lubricant. Follow the bulletin procedure to propely cover all interior trim to avoid damage from the lubrication process.

Wind Noise

It is important to understand where the wind noise is coming from.

Apply masking tape to the outside of the roof in the suspected area, then test drive the vehicle. After identifying the location, refer to the bulletin for the recommended repairs.

From the front -- could be leak from roof to seal or seal to front glass panel.

Roof to seal -- adjust front mounting bolts

Glass to seal -- adjust front glass panel

From sides -- adjust side mounting bolts

From corners -- adjust corner mounting bolts

Refer to the bulletin for additional details on repair procedures and updated module seal and cross car glass panel foam (fig. 16) part information.


TIP: Some leakage is normal at the T-joints by design.

TIP: Do not order an entire module to obtain the updated seal.

TIP: Call Webasto Sunroof at 1.800.995.5911 for persistent issues before replacing the module.

- Thanks to Ashmi Haria and Ray Romeo

Body Control Module (BCM) Grounds

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This information applies to 2006-07 Buick Lucerne, Cadillac DTS, Chevrolet Impala, Monte Carlo, 2007 Cadillac SRX, Chevrolet Avalanche, Equinox, Silverado, Suburban, Tahoe, GMC Acadia, Sierra, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL, Pontiac Torrent, and Saturn Outlook.

It is important to properly install and verify BCM grounds whenever a BCM is serviced or replaced.

Before disconnecting a BCM ground, disconnect the negative battery cable, or disconnect all other connections to the BCM first. Failure to disconnect all powered connections before disconnecting the ground may result in damage to the BCM.

If the BCM grounds are not correctly installed, damage to the BCM may occur. Other systems controlled by the BCM may also become inoperative or intermittent:

- Interior lighting

- Remote Keyless Entry

- Door locks

- Power windows and mirrors

TIP: Refer to bulletin 07-08-47-004 for more information.

- Thanks to Peter Vadhanasindhu and Dennis Richey

Passenger Sensing System Correction

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There was an error in the explanation of the flashing codes in the Passenger Sensing System article on page 7 of the April issue. Here is the correction, shown in red.

Then it will display the most significant digit of the DTC by commanding the OFF telltale to flash for a number of times representing the digit.

After the most significant digit has been displayed, the system will display the least significant digit by flashing the ON telltale.

For example, DTC 36 will flash the OFF telltale 3 times, then the ON telltale 6 times.

- Thanks to Esther Anderson


Recreational Vehicle and Trailer Towing

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This information applies to the 2007 Saturn Outlook and GMC Acadia. Details will be covered in an upcoming bulletin. Here are highlights.

Towing with Vehicles without Trailer Provisions (RPO V92)

These vehicles can tow a maximum trailer weight of 2,000 lb. (907 kg).

These vehicles must be modified by installing a new underhood bussed electrical center (UBEC) to provide full functionality for 4 circuits: ground, tail lamps, RH and LH stop/turn lamps.

To find the original part number, remove the UBEC and look at the side of the UBEC.

TIP: This UBEC replacement should be performed only for customers who perform trailer towing.

Towing with Vehicles with Trailer Provisions (RPO V92)

These vehicles can tow a maximum trailer weight of 4,500 lb. (2,041 kg) 
(fig. 17).


It is necessary to modify the wiring harness at the Body Control Module (BCM).

Disconnect the X7 connector from the BCM and remove terminal pin 3 (dark blue wire, 38 circuit). Re-connect the X7 connector.

Splice this wire into the wire at BCM connector X6, pin 2 (light green wire, 24 circuit).

Recreational Vehicle Towing (Dinghy Towing)

Recreational vehicle towing means towing the vehicle behind another vehicle, such as behind a motorhome.

Dinghy towing -- towing the vehicle with all four wheels on the ground

Dolly towing -- towing the vehicle with two wheels on the ground and two wheels on a dolly

TIP: To avoid battery rundown while towing, disconnect the battery before towing. 

Vehicles with a 6-speed automatic transmission that are dinghy towed must be started and run for a minimum of five minutes at the beginning of each day and at each fuel stop.

* Unlimited miles at 65 mph (105 km/h). To avoid vehicle damage, never exceed 65 mph (105 km/h). The repairs would not be covered by the warranty.

IMPORTANT: The owner must observe all procedural steps in the bulletin when dinghy towing.

Before starting, do the following steps:

- Secure to tow vehicle.

- Ignition OFF.

- Set parking brake.

- Ignition to ACCESSORY.

- Shift transmission to NEUTRAL (N).

- Disconnect negative battery cable. Release parking brake.

At destination, do the following steps

- Set parking brake.

- Reconnect negative battery cable.

- Ignition OFF

- Remove key from ignition.

- Thanks to Mark Haning

Bed Rail Stake Pockets

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Some owners of a 2007 Silverado or GMC Sierra may comment on the openings under the bed rails near the stake pockets (fig. 18). While the openings on the new Silverado and Sierra are more visible, the Classic Silverado and Sierra had similar openings around the stake pockets. The openings are required for the unique forming process of the new pickup box side inner stamping. The new design has equivalent performance for dust and moisture intrusion when compared to the previous design.


TIP: The pickup box is not designed to be sealed completely from dust or moisture intrusion.

- Thanks to Jim Will

Flashing A/C Indicator Lamp

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This information applies to the following vehicles:

2007-08 Chevrolet Silverado, Avalanche, Tahoe, Suburban, Equinox, GMC Sierra, Yukon/XL, Acadia, Cadillac Escalade/ESV/EXT, Saturn Outlook, Pontiac Torrent

2006-08 Chevrolet Impala

2006-07 Chevrolet Monte Carlo

2008 Buick Enclave, Saturn VUE

Some owners may comment that the A/C indicator lamp on the HVAC control head flashes then turns off after the A/C button is pressed. Or the recirculation indicator on the HVAC control head flashes then turns off after the recirculation button is pressed.

This is normal operation for the HVAC control module and indicates that the A/C or recirculation function is not available at the time the button is pressed. 

Reasons A/C may not be available
- Ambient air temperature is too low (if equipped with Ambient Air Temperature Sensor)
- Vehicle voltage less than 9.5V
- Refrigerant pressure too low
- Refrigerant pressure too high
- Engine coolant temperature too high
- Engine is not in RUN
- HVAC control head is in the OFF position 

Reasons Recirculation may not be available
- Mode switch in Floor, Defog, or Defrost mode 

TIP: Calibrated values vary by vehicle. Consult the appropriate vehicle SI for detailed HVAC description and operation.

The reason(s) A/C is presently disabled can be viewed with the Tech 2 by navigating to the HVAC Data display and viewing the A/C Permission parameter.

Do not replace the HVAC Control Module for a flashing A/C indicator or flashing Recirculation Indicator, as this is normal operation.

- Thanks to Michelle Delaporte, Jeff Garfield and Marty Case

Water Leak in Right Floor Area

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The owner of a 2003-07 Saab 9-3 may comment on wet carpet on the right side floor. An area under the bulkhead cover on the passenger side may have had sealer improperly installed.

This condition could cause a leak at the A-pillar that could allow water into the front foot well and rear floor. The leak path is down the A-pillar to the front floor and then rearward underneath the carpet and insulation collecting in the rear floor area, which is lower than the front.

Check the right rear corner of the engine compartment under the bulkhead cover for missing sealant (fig. 19). Also check the A-pillar behind the glove box from the passenger foot well side for missing sealant (fig. 20).



If no sealer is present at either location or there are skips in the sealant, remove the exiting sealant, clean the surfaces and apply new sealant. Test for leaks.

- Thanks to Jeff Gorenflo

Seat Belt Stop Button Replacement

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This information applies to all GM vehicles. All seat belt retractor assemblies contain a stop button (fig. 21). If a stop button becomes damaged, the button can be replaced by ordering a replacement button through the GM parts catalog. The seat belt retractor assembly does not need replacement.

Refer to document 1924486 in SI for the complete replacement procedure. If the replacement is a warranty claim, use labor code C9098 when submitting the claim.

- Thanks to Joel Ebner

Lower Timing Gear Tensioner Holding Tool Reminder

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Observe this reminder when performing the procedure covered in the March 2007 TechLink article on the Lower Timing Gear Tensioner Holding Tool Tips.

Carefully follow the repair instructions outlined in Bulletin 06-06-01-17C to properly use the Lower Timing Gear Tensioner Holding Tool (EN48464)
 (fig. 22). Failure to properly insert and secure the holding tool as instructed in the bulletin may result in a ratchet out movement of the timing chain tensioner and the need to perform additional repair steps not covered by the warranty repair time.


- Thanks to Duane Raymond

Car Issues -- Fix It Right the First Time

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Model Year(s)

Vehicle Line(s) / Condition

Do This

Don't Do This

Reference Information/Bulletin


CTS - Squeak/creak noise in front end at slow speeds while braking or turning

Intall new insulating spacer and rate washer

Don't replace entire control arm



ION -  No crank, no start, codes set

Codes set - replace ignition switch. Service part installed - Install new BCM

Don't replace BCM unless ignition switch previously replaced



Saturn VUE, Chevrolet Equinox, Pontiac Torrent - Ignition lock cylinder sticks or binds

Clean ignition cylinder lock and housing

Don't replace ignition cylinder lock and key



Cobalt, HHR, Solstice, ION, VUE, SKY - Reduced volume when tuning to AM, loss of volume after signal strength reduction

Reprogram radio

Don't replace radio.



Impala/Monte Carlo, DTS, Lucerne - Charge Light on/Battery message on DIC, codes set

Reflash BCM

Don't replace battery current sensor, generator or BCM.



Lucerne - Poor headliner fit in rear

Replace fasteners

Don't replace headliner



STS with Navigation Radio (RPO YQ4) - Numerous operating conditions

Reflash radio

Don't replace radio



ION,VUE, Equinox, Torrent, G5, Pursuit (Canada), Cobalt - Front bottom seat cover loose

Repair seat cover

Don't replace seat cover


2004-06Grand Prix, LaCrosse, Impala/MC - Low fluid in P/S systemPerform dye test to confirm leakDon't assume leak05-02-32-007C2006-07Lucerne  - Power steering clunk type noise at slow speeds

Align I-shaft to steering column 

Don't replace intermediate shaft or steering gear.06-02-35-009D

Truck Issues -- Fix It Right the First Time

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Powertrain Issues -- Fix It Right the First Time

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Model Year(s)

Vehicle Line(s) / Condition

Do This

Don't Do This

Reference Information/Bulletin


Light Duty Trucks, H2, H3, 9-7X with 4WD/AWD - Transfer case speed sensor wire harness connector comes loose or connector retainer clip breaks

Use improved connector 

Don't use old part



Rendezvous, Terraza, Venture, Uplander, Silhouette, Aztek, Montana, RELAY - Moan or groan from RDM during turning maneuvers

Perform refill procedure

Don't replace RDM if it passes tests in SI.


2005-06Malibu/Maxx, G6, Montana, Terraza, Rendezvous, Uplander, RELAY - Extended crank, starter engaged after start, low oil pressure light on, fuel gage inaccuraciesUse service calibrationsDo not replace EGR valve (bulletin 06-06-04-003B or 06-06-04-002A)06-06-04-049

Know-How Broadcasts for July

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- Thanks to Tracy Rozman

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