Sorting out Communication Problems
Technicians continue to report occasional problems with incomplete programming events or programming errors. This can lead to damaged controllers and unnecessarily high warranty.
Many of these problems can be resolved using the following tips.
Insufficient Battery Voltage --Â Be sure the battery is fully charged before starting the programming. If voltage drops too low at the end of the programming event, calibration files or VIN data may not be written, causing problems or failure.
If the battery is questionable, there are several approved methods of maintaining system voltage during programming:
- Midtronics PSC charger (July 2005 TechLink).
- Jumper packs (June 2006 TechLink)
Not Waiting --Â Before performing a programming event, you must turn the ignition key on. Do not begin programming until all modules on the vehicle have "awakened" before beginning. If you try too soon, you will get a No Communication message on the Tech 2.
TIP:Â A good rule of thumb is to observe the instrument panel lights and tones. When everything stops, you can safely proceed. Plug in your Tech 2 (and CANdi module if required).
Tech 2 Cable and Adapters --Â If you suspect that your Tech 2 cable is faulty and decide to replace it, also be sure to check the condition of the adapter.
Three 16-pin adapters have been used with the Tech 2. At a glance, they all look the same.Do not use adapter p/n 71419.
You can use either of the adapters numbered GM 3000098 (coded either VTX 02002955 or HP 5063-3255). Either of these will work with CANdi modules.
Self Test --Â Use the self test to verify the integrity of the Tech 2, interface module, and cable. For information and procedure, click on the Reference Guide on the TechLink website. Locate the article listed asÂ GM Tech2 / VCI / Cable Test.
On the Tech 2, the test is located under F3:Tool Options > Self Test > F2: Automated VCI Test. Then follow the instructions in the article.
TIP:Â The test requires use of the loop back adapter p/n 3000109.
Pre- and Post-Programming Messages --Â Be sure to read the pre- and post-programming messages in TIS or TIS2WEB, and follow the instructions you find there.
For instance, you may need to take a module off-line to reduce interruptions during programming and ensure successful programming.
- Thanks to Mark Stesney
This information applies to the 2004-07 Cadillac CTS, SRX, STS, XLR and Buick Allure, LaCrosse and Rendezvous with LY7 3.6L, LP1 2.8L V6, LH2 4.6L V8, or LC3 4.4L V8 engines.
When diagnosing concerns with oxygen sensors on these vehicles, observe these points:
1. Malfunctioning oxygen sensors will set a sensor-related diagnostic trouble code. Do not replace the oxygen sensor unless diagnosis following the appropriate document in SI indicates that the oxygen sensor should be replaced.
For example, do not replace the oxygen sensor if diagnostic trouble codes P0420 or P0430 for catalyst efficiency are present alone.
2. When replacing the catalytic converter, do not replace the oxygen sensor. Transfer the oxygen sensor from the old converter to the new converter.
3. Oxygen sensors that are damaged due to underbody impact are not covered under the new vehicle warranty.
4. DO NOT cut the wires of the oxygen sensor when replacing it.
- Thanks to Dave Dickey
When you're using your Tech 2, have you ever wondered what a certain abbreviation or acronym stands for?
There's now an extensive list of Tech 2 Abbreviations and Acronyms in the Reference Guide section of the TechLink website. These are the terms that are actually used on the Tech 2 display screen.
TIP:Â There's also a list of abbreviations and meanings that are used in SI.
Follow this path in SI:
build vehicle > general information > general information > introduction > abbreviations and meanings
- Thanks to Mark Stesney
The Tire Pressure Monitor (TPM) system is a standard feature on all 2007 Buick Rainier, Chevrolet Colorado and Trailblazer, GMC Canyon and Envoy and Saab 9-7x models. RPO UJ6 will not be specified on the option code list.
Some service information may state that the spare tire is equipped with a TPM sensor. This is not correct. The spare tire is not equipped with a TPM sensor on any of the vehicles listed above. Refer to SI for all service procedures.
TIP:Â The Hummer 3 does have a TPM sensor in the spare tire.
- Thanks to Dino Poulos
On some 2007 full-size utilities, the driver's outside mirror (either power fold or manual fold) may vibrate or shake while driving. According to bulletin 06-08-64-027, this may be caused by one of the following:
- Loose glass actuator (motor)
- Power folding mirror (RPO DL3) assembly may have been folded or unfolded manually or the mirror was accidently obstructed while power folding.
With theÂ power foldÂ option, cycle the mirror three times.
With theÂ manual foldÂ mirror, manually fold/unfold the mirror three times.
With either mirror, check the mirror for stability, performance and vibration. If folding the mirrors three times does not improve stability, remove the glass assembly per document 1694905.
Check tightness of the four glass actuator screws shown in document 1731190. Torque 10-14 in lbs (1.13-1.16 Nm)
Bend the metal spring finger up approximately 1/2 inch (12.7 mm) to increase engagement to the housing.
Install the glass assembly.
TIP:Â Be careful not to allow the spring finger to unseat from its intended track in the mirror housing.
Check for stability, performance and vibration. If stability is not improved, replace the mirror assembly per document 1740757.
- Thanks to Paul Radzwilowicz
Some owners of the 2006 Hummer H2 Special Edition may comment that the compass in the rear vision camera rear view mirror cannot be calibrated.
The compass will not calibrate if the vehicle is placed in Reverse before completion of the calibration procedure.
It is necessary to complete the calibration procedure driving in a forward direction only. Do not put the vehicle in Reverse during the calibration procedure.
- Thanks to Terry Nicholas
2007 Cadillac Escalade models equipped with a SuperNav Radio (RPO U3R) and the factory video system (RPO U42) have a parental control system. The rating level limits playing DVDs with a certain rating. The rating selections are 1 through 8, with 1 (kid safe) being G rated. To change the rating level, press the Parental Level button, then press the Password button. Type in the password, then change the rating level.
If the password has been forgotten, follow this procedure.
1. Place a store-bought DVD into the SuperNav Radio.
2. When the DVD screen appears, press the Options softkey on the upper left part of the screen. Then select the Setup softkey on the bottom of the screen.
3. Select the Settings box and then the Parental Level box.
4. Press and hold the box labeled Number 8 for 10-15 seconds until a audible beep is heard from the radio.
5. The security code is erased. You now have the option to input a new security code or leave the parental controls unsecured.
- Thanks to Paul Radzwilowicz
Some 2000-05 Cadillac DeVilles may make an audible moan/squawk noise during low speed turning manuevers such as parking lots, driveways, etc. This condition may be due to power steering gear valve instability resulting in a pressure disturbance, which creates the audible noise. The noise is transferred to the vehicle structure through the steering column.
To correct, replace the power steering gear return hose assembly (p/n 15839169). For further details, refer to bulletin 02-02-32-001C (SI document 1846919).
- Thanks to Bill Denton
A 2006 Chevrolet Impala or Monte Carlo with 3.5 LZE engine may exhibit a crank-no-start or a start and stall concern. There may or may not be a DTC.
Remove the camshaft position actuator magnet and check for the pin in the center of the actuator being spring loaded. If the pin is not spring loaded, it may not be making contact with the center of the magnet, causing the concern. Replace the cam actuator and retest.
- Thanks to Ron Mitchell
When replacing the rear differential clutch packs in a 2006-2007 XLR and Corvette Z06, you may find a 5 plate clutch pack. SI also mentions a 5 plate pack, but service parts come as a 4 plate pack.
A change to carbon fiber clutch plates in these models, which increased overall thickness, makes it necessary to reduce the stack to 4 plates. The correct stack using the new design plates is 4 plates and will not affect performance.
TIP:Â This change does not apply to the normal Corvette.
- Thanks to Charles Krepp
Some owners of a 2004-05 Chevrolet Silverado or GMC Sierra with 6.6L RPO LLY engine may comment that the SES MIL is on. When DTCs are checked with the Tech 2, a U0100, U0101, U0105, and/or U0106 will be set.
The ECM, TCM, FICM, and Glow Plug Controller communicate among each other on circuits 2361 and 2362 (CAN Bus). The Tech 2 does not communicate on these circuits.
In most cases, if all of the listed DTCs are set, the CAN Bus circuits may be shorted to ground at the FICM/generator bracket. Before replacing any parts, perform a thorough visual inspection of the wiring harness near the FICM/generator bracket and repair as necessary if shorted.
- Thanks to Jim Will
The 2000-2006 full-size utility truck Electronic Suspension Control Module Replacement procedures in SI have been revised. The revisions made were to the programming procedures or links to the programming procedures.
TIP:Â When replacing the ECU you must reprogram with the latest software.
- Thanks to Dan Stress and Gary G. Clark
This information applies to the 2005-07 Chevrolet Corvette and Cadillac STS and 2004-07 Cadillac XLR.
A no crank, no start condition with a Driver Information Center (DIC) message that displays "No FOB Detected" can be caused by a low battery state of charge (SOC). The Remote Control Door Lock Receiver (RCDLR) will not function if the battery SOC is below 9V.
TIP:Â To enter the Corvette, use the conventional key in the cylinder above the license plate to open the hatch. On the XLR, the key cylinder is located behind a cover on the lower rear fascia. Then use the door release tab inside the trunk to unlatch the driver's door. For the STS, just unlock door with key in conventional fashion.
Check the battery state of charge and if low, diagnose the cause of the weak battery before performing any other repairs.
- Thanks to Dino Poulos
On 1999-2007 full-size trucks, in order to avoid HVAC actuator damage, DO NOT apply power to the actuator when it's not installed in the HVAC module.
- Thanks to Robert Tette and Art Krygowski
Removal vs. Replacement
In the Engine Mechanical subsections of SI, and within the Repair category, there are two sets of procedures.
ReplacementÂ procedures can be performed on-vehicle.
Removal and InstallÂ are off-vehicle procedures.
Note that the off-vehicle procedures usually begin after Engine Oil and Oil Filter Replacement. But many off-vehicle procedures can be performed on vehicle, too; for instance, replacement of a cylinder head.
The procedure titled Crankshaft and Bearings Removal is not a complete procedure. Other procedures must be performed first (engine removal, for instance) but not all those listed before this procedure.
The same is true for Crankshaft and Bearings Install. Other procedures must be performed before and after (engine installation, for instance) but not all that are listed.
The off-vehicle procedures are listed in an order for a complete engine disassembly and assembly. In the case of crankshaft replacement, service engineers assume that a reasonably trained and experienced technician knows the basics of engine service, and therefore knows what is required, beginning with engine removal from the vehicle.
In the near future, engine repair procedures will receive additional titles in SI. Replacement procedures will be titled On-Vehicle. Removal or Install procedures will be titled Off-vehicle, or perhaps Unit Repair.
- Thanks to Jerry Garfield
On some 2003-06 Chevrolet SSRs, aftermarket window tint may tear or have vertical scratches. This is noticed primarily when the window travels full up or down.
Because the upper doors have no A-frame or upper door channel like most vehicles, there are guide pads in the door to support the glass. These guide pads make contact with the glass during the vertical movement of the glass, which may damage aftermarket window tint.
GM does not recommend or support the use of any aftermarket tint in any GM vehicle. The aftermarket tint should be removed to correct this concern.
- Thanks to Ron Erman
Some owners of 2007 full-size utilities with RPO AN3 may comment that they are unable to set a personalized easy exit seat position and the seat will move back only a predetermined amount.
Unlike the previous model years, the new 2007 utilities move the seat rearward approximately 3 inches when the easy exit feature is activated. If the owner wishes to have the seat move back further, the exit button can be pressed and the seat will move back an additional 3 inches for each press until the seat is all the way back. Please advise owners with this concern of the new operating characteristic.
- Thanks to Jim Will
Owners of some 2007 full-size utilities with RPO U3U or UVB may comment that the navigation radio volume control does not function and seems to be stuck at a very loud level. This may occur after the radio has been repaired or replaced in service.
If the incorrect radio calibration is selected in TIS, the navigation radio may experience a loss of volume control. To repair the concern, reprogram the navigation radio referencing the correct RPO options of the vehicle, to verify the radio is programmed correctly.
- Thanks to Paul Radzwilowicz
Owners of some 2007 full-size utilities with manual HVAC controls (RPO CJ3) may experience a low coolant level message on the DIC at times. These vehicles are not equipped with a low coolant level sensor. The low coolant level message may appear due to a software anomaly with the manual HVAC control head (RPO CJ3).
Do not replace the instrument panel cluster or HVAC control head to resolve this concern. Reprogram the HVAC control head with updated calibrations. This new service calibration was released with TIS satellite data update version 6.0, available May 30, 2006.
As always, make sure your Tech 2 is updated with the latest software version.
- Thanks to Paul Radzwilowicz
This information applies to the 2007 full-size utilities and the 2005-07 Chevrolet Silverado Classic and GMC Sierra Classic (1500 models).
Some owners may comment on a scored appearance of the front brake rotors. Scoring could be caused by the formula of the front brake lining, which has ingredients to clean rust from the rotor braking surface. This cleaning feature of the rotor braking surface may have a side effect of scoring.
This scored appearance is normal as long as no other symptoms are experienced, such as pulsation, roughness, or noise, and the scoring does not exceed the specification in SI document 1476240.
- Thanks to Jim Will
There are times when being able to quickly obtain a needed service part is critical -- a customer's vehicle is down -- and the normal order/supply process has to be expedited. This is a task for the Service Parts Assistance Center (SPAC).
TIP:Â It's a good idea to try to obtain the part locally before contacting SPAC.
When a part is needed on an urgent basis, your dealership Parts Manager or other representative will upgrade the order to a SPAC Case using RAPID (EPIC in Canada), TRACS or EPIC (VIN is required).
SPAC Parts Escalation
When a parts situation is extremely urgent, Bulletin GMP05-135 explains how to follow up on a SPAC case. Your inquiry will be escalated through a defined process. Here are some highlights. Refer to the bulletin for details.
The dealership representative should initially call TRACS or access RAPID or EPIC for an update. If no information is available, the dealership representative should choose to speak to a Dealer Call Center agent. The agent will access the SPAC case database and provide the caller with the latest information.
If the information is not adequate, the dealership representative may ask that an inquiry be sent to the Service With Action Team (SWAT) for further investigation.
SWAT will respond to the dealership within 48 hours, based on SPAC's past history for case resolution. Approximately 68% of all SPAC cases are resolved within 48 hours.
TIP:Â Parts Managers may inquire and escalate their concerns immediately, based on the urgency of their situation.
Under normal circumstances, 48 hours gives adequate time for the case to navigate through the D2D Express process as well as allow for the expedition and processing of any in-transit inventory to an SPO facility.
- Thanks to Dave Gibson
This information applies to the 2005-06 Chevrolet Express, Silverado, Suburban, Tahoe, GMC Savana, Sierra, Yukon equipped with a 4.8, 5.3 or 6.0 engine.
The engine may intermittently stall, misfire, or crank without starting. There may be no trouble codes set.
Complete the SI diagnostics for any symptoms or trouble codes found. If diagnostics are inconclusive, and an intermittent stall, misfire, or a crank no start can be duplicated, inspect for a loss of Ignition 1 voltage to the ignition coils.
Wiggle test the ignition coil harnesses to see if the concern can be duplicated. Inspect splices S160 and S159 for loose connections. Also inspect connectors C148 and C149 for wires breaking near the connector. The pink Ignition 1 power feed wire may break inside the insulation near connector C148/C149.
- Thanks to Don Langer