August 2009 Archives

Fretting corrosion is a buildup of insulating oxidized debris (nonconductive material) caused by micro motion between two contact surfaces. (Fig 1)

(Fig 1)

It's commonly found on tin plated terminals, such as Micro pack 100 and Micro pack 64 connections.


Past Serviceability Issues

Replacement of sensors, modules and other components will result in only a temporary relief of a fretting issue. Actually, just the cycling of a connector will clear the fretting corrosion from the terminal, correcting the condition for a short time until fretting corrosion builds back up again.

Typical issues caused by fretting corrosion include:
-    Intermittent electrical component operations
-    DTCs being set, or No Trouble Found (NTF)
-    Low current signal circuits -- fretting corrosion (high resistance) can cause intermittent connections
-    High current power circuits -- permanent increases in the connection resistance can lead to overheating


Evidence of Fretting

Fretting usually appears as:
-    small, dark smudges on electrical terminals
-    smudges at the locations of electrical contact (Fig. 2)

(Fig. 2)

In less severe cases, it may require a magnifying glass to identify a fretting condition.


Causes of Fretting

Fretting is caused by the motion between the connector and the terminal, which can be due to:
-    Vibration - micro motion between two contact surfaces causing build up of insulating oxidized debris (nonconductive material)
-    Thermal cycling
-    Packaging of the connector, wiring harness and/or device
-    Poor connection/terminal retention


Progression of fretting corrosion

A.    Tin - clean (free of any corrosion) (Fig. 3, A)



(Fig. 3, A)


B.    A connection is made through the cracks in the tin-oxide layer, making a stable connection. (Fig. 3, B)


(Fig. 3, B)


C.    When the terminal vibrates or moves a section of the clean tin is exposed to the air and it quickly forms an insulating tin-oxide film. (Fig. 4)


(Fig. 4)

Every time there is motion at the contact spot the cycle repeats and more tin oxide is worn away and debris builds up. (Fig. 5)


(Fig. 5)

With continued microscopic fretting, enough insulating tin-oxide wear debris can build up high resistance creating intermittent connections. (Fig. 6)


(Fig. 6)


Service Solution

Disconnecting and reconnecting a connector will temporarily "fix" a fretting condition, but it will eventually come back if the conditions for fretting still exist. The best preventative measure is to perform the following:
1.    Disconnect the appropriate module(s)/connector(s)
2.    Lube both sides of the connector (module side and harness side) with NyoGel® 760G lubricant, GM part number 12377900 (in Canada, P/N 10953529) (Fig. 7)


(Fig. 7)

3.    Reconnect the connector
4.    Wipe away any excess lubricant
5.    Duplicate the condition per the SI Diagnostic Procedure Instruction section
- Circuit/System Description
- Conditions for Running/Setting the DTC
- Circuit/System Verification

IMPORTANT: If the condition CANNOT be duplicated, the repair is complete. DO NOT replace the module/component/part.

IMPORTANT: If the condition can be duplicated, the repair is incomplete. Follow the appropriate SI Circuit/System Testing procedure.

For all intermittent service lamps or electrical module/component/system operation, in addition to those exhibiting a fretting condition, it's recommended to disconnect the appropriate module(s)/connector(s) and lube both sides of the connector (module side and harness side) with NyoGel 760G lubricant.

For more information on the terminal repair procedure, refer to service bulletin #09-06-03-004.


- Thanks to Rob Prough, Keith Borowy and Pamma Chana

Many users may begin to see an error screen while trying to launch the new Global Diagnostic System (GDS) software. (Fig. 8)


(Fig. 8)


GDS uses security as an embedded part of the application. In order to access and open GDS, there is a seven day lease renewal that is issued that allows users to run the program. If you have NOT opened up GDS within the last seven days from TIS2WEB, an error message will appear when attempting to launch the program from the desktop icon.

Fortunately, the solution is simple: logon to GM Global Connect, launch TIS2WEB and open GDS from the TIS homepage. This will renew the lease and you will then be able to launch GDS from the desktop icon.

IMPORTANT: You must launch GDS once every seven days from within TIS2WEB.

In addition, if you have not taken the online GDS training course (16048.26W), it can be found at www.gmtraining.com.


- Thanks to Mike Lontine and Milad Mansour

Technicians may have noticed that some schematics and diagnostic procedures in the Service Information show a component code along with the part name (for example, K36 SDM). So, what exactly is K36?

Today, with General Motors vehicles sold globally, the Service Information is written once and then translated into many different languages. The schematics and diagnostic procedures are translated into other languages at different times by different individuals. This can cause a part name to appear differently between the two documents, such as purge solenoid vs. purging solenoid.

To assist the technician in identifying a common part when the part names appear differently, a component code is created. These codes are not translated, so they are always the same even though the part name may have a slight variance after translation. The component codes will always be the same once assigned to a unique part name and will only be found on the schematics, their support information, and in the diagnostic procedures Circuit/System Verification, Circuit/System Testing, and Component Testing categories.


Schematics and Support Information

The component codes used on the schematics will have the base code with an extension to identify location or quantity. (Fig. 9)


(Fig. 9)


Here's an example: the ABS wheel speed sensors are identified on the schematic with a base code (B5) and a location extension (LF, RF, LR, and RR) as listed below:
-    B5LF Wheel Speed Sensor (WSS) - Left Front
-    B5RF Wheel Speed Sensor (WSS) - Right Front
-    B5LR Wheel Speed Sensor (WSS) - Left Rear
-    B5RR Wheel Speed Sensor (WSS) - Right Rear

B5 is the base code for the wheel speed sensor and the LF, RF, LR, and RR indicate the location on the vehicle.

In addition to the schematics, these codes will also appear in the master electrical component list, connector end views, and component/harness routing view legends. In order to maintain the sequence of lists in all languages, the master list and the connector end views will be sorted by component code rather than by component name.

Because not all fuse blocks have labels showing abbreviated fuse names, a fuse code will be assigned for each fuse as well. Fuse names will be identified by four characters and will be specific to the vehicle publication.

1st Character
F = Fuse, Circuit Breaker

2nd Character
Position number within the block

3rd Character
Alpha character defining the block position within the vehicle
U = Engine Compartment (underhood)
D = I/P (within instrument panel)
P = Passenger Compartment (not in I/P, can be in center console)
R = Body Rear (rear of the passenger compartment or rear compartment)

4th Character
Alpha character (starting with A, B, C ...) identifying whether there is more than one block residing in the same area on the vehicle within the same vehicle publication.

Examples:
-    Fuse 11 on a vehicle with one block within the engine compartment would be F11UA
-    Fuse 13 of a vehicle with two blocks within the engine compartment would be F13UA and F13UB

Only the assigned fuse codes will appear on the schematic graphic. Both the assigned fuse code and the name on the label (if one exists) will appear in the fuse block usage table within the Electrical Center Identification Views document located in the Wiring Systems and Power Management category.


Diagnostic Procedures

The diagnostic procedures will use the base code (B5) for a wheel speed sensor, but may or may not use the extension identifying location (LF, RF, LR, and RR).

For example: Ignition OFF, disconnect the harness connector at the appropriate B5 wheel speed sensor.

This is done so the diagnostic procedure can be common for all four wheel speed sensors and not have to take into account part location or quantity. When the diagnostic procedure states "the appropriate" part, it is up to the technician to identify which component is being diagnosed by the symptom stated on the repair order (e.g., driver's door lock is inoperative) or by the DTC descriptor (e.g., DTC C0585 04 - Left Rear Actuator Circuit Open).

Now, the next time you read about a K36, you'll know that it is a Sensing and Diagnostic Module in any language.


- Thanks to David Nowak and Lou Winters

The Electronic Service Centers continue to receive radios (with concerns relating to navigation and non-navigation systems, DVD players, infotainment systems, CD drives and changers, and XM connectivity issues) returned under warranty that are fully functional. The associated repair orders often do not properly define the condition, cause, and correction. All too often the repair order simply states "radio inop, replace radio."

Whenever a radio-related customer complaint is received, it's critical to accurately document the following on the repair order:
-    Description of the customer complaint
-    Complete list of all diagnostic steps, including test equipment readings and all DTCs
-    Detailed explanation of what corrected the condition

Refer to warranty administration bulletin #04-00-89-015A for more details on repair order requirements.

In addition, a copy of the repair order must be included with a radio returned to the Electronic Service Centers as outlined in bulletin #08-08-44-029A.

A returned radio with no trouble found and without a complete repair order may be subject to a warranty claim debit.


- Thanks to Terry Nicholas

The Passenger Presence System (PPS) on 2009-10 full-size trucks -- Escalade, Suburban, Tahoe, Yukon, Yukon Hybrid Denali (excluding Tahoe Hybrid and Yukon Hybrid), Sierra, Silverado and Avalanche -- is comprised of three components: a control module and sensing mat that are part of the passenger seat assembly and a Belt Tension Sensor mounted in the belt buckle assembly.

The PPS is calibrated as a system and parts cannot be replaced individually. A service kit is available that includes the seat cushion foam, a PPS sensing mat and a control module. Even though the production and service parts look alike, they are not interchangeable. But before replacing any components, here are some service tips to keep in mind when diagnosing the PPS.


DTC B0081

There are several conditions for setting DTC B0081 (Passenger Presence System). Here are the primary causes.



Setting a DTC B0081:5A (in the PPS) will cause a DTC B0081:0F in the SDM. Communication errors will occasionally occur. Clearing codes and cycling the ignition should remove the DTC. If not, follow the SI instructions for active DTCs. Do not replace a part based on a history code only.


Service Tips for PPS

-    Verify the customer complaint before diagnosis.

-    DTC B1325 (battery voltage out of range) can cause codes in the PPS module. If a vehicle has a DTC B1325, correct the battery voltage issue before diagnosing the PPS module. Once DTC B1325 has been repaired, check for active codes in the PPS module. If the PPS codes are in history only, do not replace the PPS module. If there are active codes in the PPS, follow the service procedures for each DTC.

-    Specify whether the front passenger airbag ON/OFF lamp or the SIR lamp (on the instrument cluster) is the source of the customer complaint.

-    Pull PPS codes in addition to SDM codes. The PPS codes are available via the Tech 2. If codes are cleared, include that on the repair order.

-    Specify if the codes pulled are in history or are current (active).

-    Flash codes are not available on the 2009-10 models. DTCs will need to be retrieved using the Tech 2.

-    The PPS system for 2009-10 full-size trucks does not need to be re-zeroed. There is no re-zero command available on the Tech 2. The re-zero function is only operational for the Tahoe Hybrid and Yukon Hybrid.

-    If you are replacing multiple SIR parts for a single customer complaint, you are most likely replacing good parts. It is very rare that two different SIR components fail at the same time. If diagnosis indicates the need to replace the PPS and BTS or PPS and SDM, please call TAC for assistance.

-    If there are multiple DTCs and you are not sure which module to replace first, contact TAC for assistance.


PPS Online Video

For additional information about the operation of the PPS on full-size trucks, a streaming video is available from the U.S. GM Training website. Click Web Video Library from the main menu, then Technical, and then keyword search Occupant. Occupant Safety System Update, 10208.13D (in Canada, 10208.13V), is at the top of the list. To order a copy of the video, call 1-800-393-4831.


- Thanks to Carmen Richmond

For 2010, the Tire Pressure Monitor (TPM) sensors on the Corvette are new and they will not read data from previous model years.

If a TPM sensor from a previous model year is installed on a 2010 Corvette, the sensor will not learn (the new sensor ID information will not be sent to the receiver).

The previous sensor is part number 25758220 (used up until MY 09). (Fig. 10)


(Fig. 10)


The new sensor is part number 15268606 (begins use in MY 10; common with HHR SS, Cobalt SS, CTS-V series). (Fig. 11)


(Fig. 11)


TIP: TPM service procedures, such as the relearn procedure, torque procedure, and installation and removal procedure, remain the same.


- Thanks to Art Spong

This information applies to 2009 vehicles with the following 4-cylinder engines:

- 2.0L RPO LNF
- 2.2L RPO LAP
- 2.2L RPO LE8
- 2.4L RPO LAT
- 2.4L RPO LE5
- 2.4L RPO LE9


A coolant loss may be observed in the water pump area, usually at PDI. The leak may be more prevalent with cold ambient temperatures.

1.    Confirm coolant leak at the water pump-to-block interface.

2.    Run the vehicle to operating temperature and let it cool. Repeat two times. Inspect the area for leakage.
-    If the suspected leak has stopped, no further action is needed. Return the vehicle to service.
-    If the concern is still present, continue to step 3.

CAUTION: Hot coolant could spray if the cap is fully removed.

3.    Carefully loosen the coolant cap to relieve pressure. Tighten the cap after pressure relief.

4.    Loosen the four bolts on the water pump (two on the front of engine, two on the rear of the pump) approximately one turn, but do not fully remove.

5.    Torque the bolts to 25 Nm +/- 4 Nm (18.5 ft. lb. +/- 3 ft. lbs) in the following sequence: (Fig. 12)


(Fig. 12)



A. Top bolt on front of engine
B. Lower bolt on rear of water pump
C. Lower bolt on front of engine
D. Upper bolt on rear of water pump

TIP: A crow's foot wrench may be used where required to ensure the torque value is met.

6.    Top the coolant in the surge tank to the cold full mark.

7.    Clean and ensure all residual evidence of leaks is removed from the top and lower section of the water pump.

8.    Pressure check and run the vehicle to operating temperature to check for coolant leak at the water pump-to-block joint. Let the vehicle cool and heat cycle two additional times.
-    If the suspected leak has stopped, no further action is needed. Return the vehicle to service.
-    If a leak is still present from the O-ring area after the re-torque of the water pump, replace the water pump O-ring. Be sure to follow the sequential torque procedure listed above when replacing the O-ring.


- Thanks to Jeff Gorenflo

On a 2007-09 Solstice GXP or SKY Redline, there may be a gurgle or knock noise from the heater core area, a low heat condition and the coolant temperature gauge may read high intermittently.

These concerns may be caused by an air pocket in the cooling system. This vehicle configuration is susceptible to air pockets entering the cooling system if the reservoir cap is removed. DO NOT open the cooling system on a warm car. Doing so will induce air into the cooling system.

TIP: Any time the cooling system is bled, lift the driver's side of the vehicle slightly to insure the reservoir is the highest point in the system.

Air can enter into the system from the reservoir bleed port. With the vehicle parked on a level surface, be sure the coolant recovery container is level in the vehicle and the bleed port is above the engine outlet port. You should be able to place your finger between the inner fender and the lower front edge of the coolant container. If you have to move the front of the container up, be sure the coolant container or cap does not contact the underside of the hood when closing.

To remedy this concern, use a Vac-N-Fill coolant filler while slightly raising the driver's side of the vehicle. Repeat this process three times to ensure all air is removed from the system.

After filling, run the vehicle to achieve operating temperature (the cooling fans cycle) and test drive to verify the concern has been repaired.

TIP: Vac-N-Fill instructions can be found in SI under Engine > Engine Cooling > Repair Instructions > Cooling System Draining and Filling (GE-47716).


- Thanks to Jeff Gorenflo

Some 2009 Malibu, G6, and AURA models equipped with the 2.4L L4 engine and 6T40MH8 6-speed automatic transmission may have an SES light on with a DTC P0723. Technicians may not be able to duplicate this condition.

A new calibration labeled "Change to address P0723 Toss intermittent diagnostics" is available in TIS2Web update (4.5), which was released in April. Installation of this calibration for the TCM should correct this condition.

TIP: Toss stands for Transmission output speed sensor.


- Thanks to Ron Mitchell

The owner of an Escalade, Silverado, Tahoe, Sierra, or Yukon equipped with the Two-Mode Hybrid option may comment that the Auto Stop function does not operate at all in hot or cold temperatures or takes a long time to activate in cold ambient temperatures. Customers may also comment that fuel economy is less than expected. This concern may be considered a normal condition with certain conditions and driving maneuvers.

Inform the customer that ambient conditions and driving habits have a direct correlation with fuel economy. The Auto Stop mode may not be enabled if certain hybrid and vehicle components are too hot or too cold.

In warm temperatures, the hybrid batteries, the hybrid cooling system and the engine must all be kept cool for Auto Stop mode. Running the interior air conditioning and keeping the hybrid battery vents unrestricted will help keep the hybrid batteries cool.

In cold temperatures, the hybrid battery module temperature, engine coolant temperature, transmission fluid temperature, and cabin temperature must be warmed up before Auto Stop is allowed. The hybrid controllers also monitor ambient temperatures and interior temperature along with the above mentioned criteria to determine desired Auto Stop conditions.

The Auto Stop criteria are highly dependent on the outside air ambient temperature. Depending upon the overnight soak time, specific drive cycles, and the factors listed above, it may take an hour before the first Auto Stop occurs.

Observed fuel economy is affected by heavy acceleration, which requires more engine operation and, thus, more fuel consumption. Also, heavy braking does not allow regenerative braking to occur.

Fuel economy will be the same as a base truck under heavy throttle and brake apply. Adjusting both braking and acceleration driving habits will result in the higher system efficiency. Refer the customer to monitor Active Fuel Management (AFM) information on the hybrid navigation/radio display screen or the efficiency gauge to learn driving habits and conditions that improve fuel economy. This includes trying to keep the efficiency gauge in the green zone as much as possible and trying to drive in 4-cylinder mode as long as possible. The transmission gear shift selector should be placed in Drive and not in Manual for best fuel economy. Auto Stop is inhibited in the Manual transmission shift ranges.

Additional tips to improve fuel economy include keeping tires properly inflated, accelerating to allow for as much Mode 1 electric propulsion as possible, limiting the use of remote start, reasonable highway speeds, minimizing unnecessary cargo or mass, and keeping the transfer case in 2WD instead of Auto.

If there are no DTCs found in the vehicle control modules that would prohibit Auto Stop and the hood switch reads correctly, this condition should be considered an operating characteristic. Monitor the HPCM (Hybrid Powertrain Control Module) and Auto Stop Inhibit Reason data list to identify the normal inhibit reason.


- Thanks to Chuck Krepp

The owner of a 2008-09 TrailBlazer, Colorado, Canyon, Envoy, H3, H3T, or Saab 9-7x with inline 4/5/6 cylinder engine (RPO codes LLV, LLR, LL8) may experience a SES light and an engine misfire with DTCs P0300-P0306 stored in the ECM.

This condition may be the result of water in a spark plug well. If the top of the engine is exposed to a lot of water, it can drain down the vented threads of an ignition coil bolt, flow through the vent in the bottom of the related ignition coil bolt hole, and collect in the related spark plug well.

If SI diagnosis does not isolate the cause of this condition, remove the related ignition coil(s) and inspect the spark plug well for standing water.

If there is no sign of water, this information does not apply.

If water is present, extract the water and replace the related spark plug and ignition coil with new components.

IMPORTANT: Before installing the new ignition coil, fill the bottom of the ignition coil bolt hole with Loctite 565 PST Thread Sealant and apply it to the ignition coil bolt threads as well. (Fig. 13)


(Fig. 13)


For Hummer H3 models, also perform the following steps after the repairs above are complete:

1.    Remove the hood air grille by following Hood Air Grille Replacement in SI.

2.    Follow Steps 2a-2e to install foam gasket tape and reduce the chance of water dripping directly on the No. 1 ignition coil when the hood is power washed.

2a.    Remove the flat retaining blade from the retaining clip. (Fig. 14)


(Fig. 14)



2b.    Cut a piece of two-sided foam gasket tape the same size as the flat retaining blade.

2c.    Cut a lengthwise slit in the center of the foam gasket tape.

2d.    Install the foam gasket tape over and around the retaining clip, leaving the tip of the clip exposed through the slit.

2e.    Install the flat retaining blade on the retaining clip. The foam tape will be between the flat retaining blade and hood air grille.

3.    Install the hood air grille following Hood Air Grille Replacement in SI.

4.    Inspect all the hood air grille retaining clips under the hood to ensure that they are all engaged, and make sure the hood air grille fits tight against the hood.

5.    Advise customers to use care when washing the hood of their vehicle. They should not apply extreme water pressure directly on the edge of the hood air grille when washing their vehicle. (Fig. 15)



(Fig. 15)


- Thanks to Jamie Parkhurst

This information applies to Cobalt, Cobalt SS, HHR, HHR SS, Malibu, G5, G6, Pursuit (Canada), AURA, ION, and VUE equipped with the following engines:

- 2.4L (RPO LE5/LE9/LAT)
- 2.2L (RPO L61)
- 2.2L (RPO LAP)
- 2.2L (RPO LE8)
- 2.0L (RPO LNF)

DTCs P0016 and P0017 may be caused by a camshaft reluctor that has moved on the camshaft. The condition is more prevalent if the engine has been overheated.

Before performing this procedure, confirm that the engine timing is correct. The crankshaft, camshaft and all timing indicators must line up correctly.

The procedure below was developed for the 2006-09 2.4L LE5 engine. To determine the alignment on other Ecotec engines (L61, LAP, etc.), you must compare similar engines because the reluctor position may vary.

TIP: These procedures may not detect a small movement in the reluctor. It may be necessary to compare to another like vehicle. Also note that the cam cover gasket surface does not line up with the same face or slot on the intake and exhaust reluctor.


To Check the Exhaust Cam Reluctor Position - LE5 ONLY

With the exhaust camshaft positioned so the valves for number 4 cylinder are at maximum lift (fully opened valves), the reluctor should be flush/parallel to the rocker cover gasket surface. Compare the camshaft reluctor position to the photo. (Fig. 16)



(Fig. 16)


If the reluctor does not line up correctly, the camshaft must be replaced.

TIP: The reluctor is press fit (interference fit) and is not indexed/keyed to the camshaft. An overheat condition may contribute to the concern, causing the reluctor to spin on the camshaft when hot.


To Check the Intake Cam Reluctor Position - LE5 ONLY

With the Intake camshaft positioned so the valves for number 1 cylinder are at maximum lift (fully opened valves), the reluctor should be flush/parallel to the rocker cover gasket surface. Compare the camshaft reluctor position to the photo. (Fig. 17)



(Fig. 17)
 

If the reluctor does not line up correctly, the camshaft must be replaced.

TIP: The reluctor is press fit (interference fit) and is not indexed/keyed to the camshaft. An overheat condition may contribute to the concern, causing the reluctor to spin on the camshaft when hot.


- Thanks to Jeff Gorenflo

Some 2010 Camaro owners may comment that their A/C does not blow cold enough. This could be due to selecting the incorrect setting from the HVAC controls.

For Max A/C operation, follow these instructions.

1.    Temperature must be set on the maximum position rather than being placed on the blue dot. There is an additional detent to the left of the blue dot. The temperature knob should be set on the maximum setting for coldest A/C performance. (Fig. 18)


(Fig. 18)


2.    HVAC air outlets should be set to the vent position (on the left knob, the top button with the arrow-pointing-to-the-head icon).

3.    Fan knob should be set to medium or higher (twelve o'clock position or greater).

4.    Be sure the A/C is turned on (on the right knob, snow flake LED is illuminated).


- Thanks to Dino Poulos

10209.09D -- Emerging Issues

September 10, 2009
9:30 AM and 12:30 PM Eastern Time

New Model Features

For Web NMF courses, log on to the GM Training Website (www.gmtraining.com). Select Service Know-How/TechAssists from the menu, then choose New Model Features for a selection of courses.


- Thanks to John Miller