Cellular Communication System: Diagnosis Chevrolet TrailBlazer I

Diagnostic Starting Point - Cellular Communication

Begin the system diagnosis with DIAGNOSTIC SYSTEM CHECK - CELLULAR COMMUNICATION .

The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Data Definitions

Module Information - Software Version: This displays the 3-digit number of the software version used on the OnStar® VCIM.

Module Information Hardware Version: This displays the 1-digit number of the hardware version used on the OnStar® VCIM.

Module Information - Julian Date Of Build: This displays the day of the year the module was built.

Module Information - Year Module Built: This displays the year the module was built.

Module Information - 8-Digit GM Part Number: This displays the part number for the VCIM.

Module Information - Component Serial #8: This is the first partition of the serial number.

Module Information - Component Serial #12: This is the second partition of the serial number.

Module Information - Component Serial #13: This is the third partition of the serial number.

VCI Module Station Identification Number (STID): This is the station identification number stored in the VCIM which is used by the OnStar® Call Center.

Module ID: This displays the version of OnStar® which the vehicle is equipped with.

Electronic Serial Number (ESN): This is the electronic serial number stored in the VCIM which is used by the OnStar® Call Center

Scheme 144

Circuit Description

The Vehicle Communication Interface Module detects that the Cellular Microphone is connected through the Cellular Microphone Signal circuit and the Cellular Microphone Low Reference Circuit.

Conditions for Running the DTC

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 10 seconds.

Conditions for Setting the DTC

1. The Vehicle Communication Interface Module detects an open in the Cellular Microphone Low Reference circuit or a short to voltage in the Cellular Microphone Signal circuit.
2. The above conditions are present for greater than 10 seconds.

Action Taken When the DTC Sets

1. The Vehicle Communication Interface Module will not receive any signal from the microphone.
2. Calls can be placed but the caller cannot be heard.
3. The OnStar® status LED turns RED.

Conditions for Clearing the DTC

1. The Vehicle Communication Interface Module detects the microphone connected for 5 consecutive 100 millisecond cycles.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The Cellular Antenna is connected to the Vehicle Communication Interface Module with a RG-58 coax cable. The Vehicle Communication Interface Module polls the data from the cellular antenna once every second.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The Vehicle Communication Interface Module does not detect a cellular signal.
2. All the above conditions are present for greater than 1 second.

1. The OnStar® status LED turns RED.
2. The vehicle is unable to connect to the OnStar® Call Center.

1. The Vehicle Communication Interface Module detects the presence of a Cellular Antenna.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The OnStar® button assembly consists of three buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. Ten volts is supplied to the button assembly on the Keypad Supply Voltage circuit. Each of the buttons, when pressed, completes the circuit across a resister allowing a specific voltage to be returned to the Vehicle Communication Interface Module on the Keypad Signal circuit. Depending upon the voltage range returned, the Vehicle Communication Interface Module is able to identify which button has been pressed.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 300 ms.

1. The Keypad Signal circuit voltage to the Vehicle Communication Interface Module is less than 2.8 volts or more than 3.2 volts.
2. The above conditions are present for greater than 300 ms.

1. The Vehicle Communication Interface Module will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The Keypad Signal circuit voltage is between 2.8 volts and 3.2 volts.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The OnStar® button assembly consists of three buttons, Call/Answer, OnStar® Call Center and OnStar® Emergency. Ten volts is supplied to the button assembly on the Keypad Supply Voltage circuit. Each of the buttons, when pressed, completes the circuit across a resister allowing a specific voltage to be returned to the Vehicle Communication Interface Module on the keypad signal circuit. Depending upon the voltage range returned, the Vehicle Communication Interface Module is able to identify which button has been pressed.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 15 seconds.

1. A button is depressed or stuck for more than 15 seconds.
2. The above conditions are present for greater than 15 seconds.

1. The Vehicle Communication Interface Module will ignore all inputs from the OnStar® button assembly.
2. No calls can be placed.
3. The OnStar® status LED turns RED.

1. The button will be declared unstuck after a 50 ms normal cycle.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

The Navigation Antenna is connected to the Vehicle Communication Interface Module with a RG-174 coax cable. The Vehicle Communication Interface Module polls the data from the Navigation antenna once every second.

1. The ignition must be in the RUN or ACC position.
2. The system voltage is at least 9.5 volts and no more than 15.5 volts.
3. All the above conditions are present for greater than 1 second.

1. The Vehicle Communication Interface Module does not detect a Navigation signal.
2. All the above conditions are present for greater than 1 second.

1. The OnStar® status LED turns RED.
2. The OnStar® Call Center cannot locate the vehicle.

1. The Vehicle Communication Interface Module detects the presence of a Navigation antenna.
2. A history DTC clears after 50 malfunction free ignition cycles.
3. The Vehicle Communication Interface Module receives the clear DTC command from the scan tool.

Scheme 145

This DTC indicates an internal fault and is set within the vehicle communication interface module (VCIM). No external circuits are involved.

The microprocessor runs the program to detect an internal fault during module power up and every 10 seconds thereafter until the module re-enters the sleep mode.

The VCIM detects an internal communication malfunction.

Action Taken When DTC Sets

1. The OnStar® status LED turns red.
2. The vehicle is unable to connect to the OnStar® Call Center.

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears after 50 malfunction free ignition cycles.

Diagnostic Aids

1. The diagnostic procedure used for DTC U1500 in OnStar® systems with single module generations of OnStar® differ greatly from previous generations with two modules. While these older generations denoted a failure of the three wire bus between the modules by setting a U1500, single module OnStar® systems use this DTC to denote an internal module failure. The determination of whether a one or two module generation of OnStar® is used should be confirmed. Refer to OnStar «DESCRIPTION AND OPERATION»(ref-188872-S30402717682005090500000) .
2. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the VCIM.
3. If this DTC is retrieved as both a current and history DTC, replace the VCIM.

Scheme 146

1. The customer concern may have been due to a lack of cellular service in a given area or a failure in the National Cellular Network infrastructure that has since been corrected.
2. If the prompt OnStar request ended is heard without pressing the white dot button at the end of an OnStar® keypress, the OnStar® system at one time has made a successful cellular connection, but was unable to complete the call. If repeated calls are placed with this result, contact the General Motors Technical Assistance Center.
3. Inaccurate or aged global positioning system (GPS) position may have been due to the temporary loss of GPS signal reception by the vehicle in instances such as driving through tunnels or parking structures which restrict the navigation antenna from a clear view of the satellites in the sky.

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Symptoms - Cellular Communication

1. Perform the «DIAGNOSTIC SYSTEM CHECK - CELLULAR COMMUNICATION»(ref-188872-S28376235022005090500000) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar «DESCRIPTION AND OPERATION»(ref-188872-S30402717682005090500000) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the system. Refer to CHECKING AFTERMARKET ACCESSORIES in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «ONSTAR ONE OR MORE BUTTONS INOPERATIVE»(ref-188872-S07136383932005090500000)
2. «UNABLE TO CONTACT ONSTAR CALL CENTER»(ref-188872-S29805753702005090500000)
3. «ONSTAR BUTTON LED INOPERATIVE»(ref-188872-S07939475812005090500000)
4. «NO (OR NOISY) ONSTAR AUDIO»(ref-188872-S16673102582005090500000)
5. «MICROPHONE INOPERATIVE - CALLER CANNOT BE HEARD»(ref-188872-S21824639452005090500000)
6. «VOICE RECOGNITION INOPERATIVE»(ref-188872-S05061156962005090500000)
7. «ONSTAR STEERING WHEEL CONTROL FUNCTIONS INOPERATIVE»(ref-188872-S16006071042005090500000)
8. «GLOBAL POSITIONING SYSTEM (GPS) DATA NOT CURRENT OR INACCURATE»(ref-188872-S38666569462005090500000)

Scheme 149

1. The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure at the time of the customer's failed connection that has since been repaired may also have been the cause.
2. If an OnStar Emergency call is able to successfully connect the vehicle to the OnStar Call Center when an OnStar Call Center button press is not, there may be a failure in the ability of the OnStar system in the vehicle to be recognized by the local cellular carrier.
3. If the prompt OnStar request ended is heard, without pressing the white dot button at the end of the OnStar keypress, the OnStar system at one time has made a successful cellular connection, but was unable to complete the call. If repeated calls are placed with this result, contact General Motors Technical Assistance Center.

Scheme 150

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Scheme 154

1. If the OnStar® Call Center has not received any global positioning system (GPS) data, this is an indication that the OnStar® call was a fail to voice and may be due to a failure in the National Cellular Network infrastructure. If this occurs, contact the General Motors Technical Assistance Center.
2. Inaccurate or aged GPS position concerns made by a customer which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as driving through tunnels or parking structures while making an OnStar® keypress will restrict the navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.

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1. Turn the ignition to the OFF position.
2. Remove the right rear seat cushion. Refer to SEAT CUSHION REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) in Seats.
3. Remove the communication interface module. Refer to «COMMUNICATION INTERFACE MODULE REPLACEMENT (TRAILBLAZER, ENVOY, BRAVADA)»(ref-188872-S12355154122005090500000) or «COMMUNICATION INTERFACE MODULE REPLACEMENT (TRAILBLAZER EXT, ENVOY XL)»(ref-188872-S10866578702005090500000) .
4. Remove the navigation control processor bracket. Refer to Navigation Control Processor Bracket Replacement (TrailBlazer, Envoy, Bravada) on page 8-586 or «NAVIGATION CONTROL PROCESSOR BRACKET REPLACEMENT (TRAILBLAZER EXT, ENVOY XL)»(ref-188872-S07123607962005090500000) .
5. Pass the cellular telephone coax cable through the carpet opening.
6. Remove the seat back, left and right side. Refer to SEAT BACK REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) or SEAT BACK REPLACEMENT - REAR NO. 1 (TRAILBLAZER, EXT, ENVOY XL) in Seats.
7. Remove the front door sill plates. Refer to DOOR SILL PLATE REPLACEMENT - FRONT .
8. Remove the rear door sill plates. Refer to DOOR SILL PLATE REPLACEMENT - REAR (TRAILBLAZER, ENVOY, BRAVADA) or DOOR SILL PLATE REPLACEMENT - REAR (TRAILBLAZER EXT, ENVOY XL) .
9. Remove the center pillar trim panels. Refer to GARNISH MOLDING REPLACEMENT - CENTER PILLAR .
10. Remove the rear quarter upper trim panels. Refer to TRIM PANEL REPLACEMENT - REAR QUARTER UPPER (TRAILBLAZER, ENVOY, BRAVADA) in Interior Trim.
11. Remove the lower rear quarter trim panels. Refer to TRIM PANEL REPLACEMENT - REAR QUARTER - LEFT (TRAILBLAZER, ENVOY, BRAVADA) or TRIM PANEL REPLACEMENT - REAR QUARTER - LEFT (TRAILBLAZER EXT, ENVOY XL) , or to TRIM PANEL REPLACEMENT - REAR QUARTER - RIGHT (TRAILBLAZER, ENVOY, BRAVADA) or TRIM PANEL REPLACEMENT - REAR QUARTER - RIGHT (TRAILBLAZER EXT, ENVOY XL) .
12. Remove the left coat hook. Refer to COAT HOOK REPLACEMENT In Interior Trim.
13. Remove the tool kit carrier.
14. Remove the child restraint tether anchors. Refer to CHILD RESTRAINT TETHER ANCHOR REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) or CHILD RESTRAINT TETHER ANCHOR REPLACEMENT - REAR NO. 1 (TRAILBLAZER EXT, ENVOY XL) in Seat Belts.
15. Lift and fold the carpet over the bucket seats.
16. Remove the coax cable fasteners from the floor panel.
17. Remove the coax cable fasteners from the left third pillar.
18. Disconnect the coax cable (1) from the window mounted coupling.

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1. Connect the coax cable (1) to the window mounted coupling.
2. Attach the coax cable fasteners to the left third pillar.
3. Attach the coax cable fasteners to the floor panel.
4. Position the carpet to the floor panel, aligning the holes in the carpet to the seat studs on the floor panel.
5. Pass the cellular telephone coax cable through the carpet opening
6. Install the child restraint tether anchors. Refer to CHILD RESTRAINT TETHER ANCHOR REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) or CHILD RESTRAINT TETHER ANCHOR REPLACEMENT - REAR NO. 1 (TRAILBLAZER EXT, ENVOY XL) in Seat Belts.
7. Install the tool kit carrier. NOTE: Refer to Fastener Notice in Cautions and Notices.
8. Install the 3 tool carrier nuts to the floor studs. Tighten Tighten the nuts to 7 N.m (62 lb in).
9. Install the lower rear quarter trim panels. Refer to TRIM PANEL REPLACEMENT - REAR QUARTER - LEFT (TRAILBLAZER, ENVOY, BRAVADA) or TRIM PANEL REPLACEMENT - REAR QUARTER - LEFT (TRAILBLAZER EXT, ENVOY XL) , or to TRIM PANEL REPLACEMENT - REAR QUARTER - RIGHT (TRAILBLAZER, ENVOY, BRAVADA) or TRIM PANEL REPLACEMENT - REAR QUARTER - RIGHT (TRAILBLAZER EXT, ENVOY XL) .
10. Install the rear quarter upper trim panels. Refer to TRIM PANEL REPLACEMENT - REAR QUARTER UPPER (TRAILBLAZER, ENVOY, BRAVADA) in Interior Trim.
11. Install the center pillar trim panels. Refer to GARNISH MOLDING REPLACEMENT - CENTER PILLAR .
12. Install the left coat hook. Refer to COAT HOOK REPLACEMENT In Interior Trim.
13. Install the rear door sill plates. Refer to DOOR SILL PLATE REPLACEMENT - REAR (TRAILBLAZER, ENVOY, BRAVADA) or DOOR SILL PLATE REPLACEMENT - REAR (TRAILBLAZER EXT, ENVOY XL) .
14. Install the front door sill plates. Refer to DOOR SILL PLATE REPLACEMENT - FRONT .
15. Instal the seat back, right and left side. Refer to SEAT BACK REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) or SEAT BACK REPLACEMENT - REAR NO. 1 (TRAILBLAZER, EXT, ENVOY XL)
16. Install the navigation control processor bracket to the floor panel. Refer to «NAVIGATION CONTROL PROCESSOR BRACKET REPLACEMENT (TRAILBLAZER, ENVOY, BRAVADA)»(ref-188872-S20198801742005090500000) or «NAVIGATION CONTROL PROCESSOR BRACKET REPLACEMENT (TRAILBLAZER EXT, ENVOY XL)»(ref-188872-S07123607962005090500000) .
17. Install the right rear seat cushion. Refer to SEAT CUSHION REPLACEMENT - REAR NO. 1 (TRAILBLAZER, ENVOY, BRAVADA) in Seats.
18. Install the communication interface module. Refer to «COMMUNICATION INTERFACE MODULE REPLACEMENT (TRAILBLAZER, ENVOY, BRAVADA)»(ref-188872-S12355154122005090500000) or «COMMUNICATION INTERFACE MODULE REPLACEMENT (TRAILBLAZER EXT, ENVOY XL)»(ref-188872-S10866578702005090500000) .
19. Adjust the right seat cushion to a passenger position.

OnStar® Cellular, GPS, and Diagnostic Limitations

The proper operation of the OnStar® System is dependent on several elements outside the components integrated into the vehicle. These include the National Cellular Network Infrastructure, the cellular telephone carriers within the network, and the Global Positioning Satellite system.

The cellular operation of the OnStar® system may be inhibited by factors such as the user's range from an analog cellular tower, the state of the cellular carriers' equipment, and the location where the call is placed. Making an OnStar® keypress in areas that lack sufficient cellular coverage or have a temporary equipment failure will result in either the inability of a call to complete with a data transfer or the complete inability to connect to the OnStar® Call Center. The OnStar® system may also experience connection issues if the identification numbers for the module (STID and ESN numbers) are not recognized by the cellular carriers local signal receiving towers. OnStar® cellular connection issues such as these require the assistance of the General Motors Technical Assistance Center OnStar® Group, which coordinate with cellular carriers to resolve connection issues.

The satellites that orbit earth providing the OnStar® system with GPS data have nearly no failures associated with them. In the event of a no GPS concern, the failure will likely lie with the inability of the system to gain GPS signals because of its location (i.e. in a parking structure), hardware failure, or being mistaken with an OnStar® call which has reached the Call Center without vehicle data.

During diagnostic testing of the OnStar® system, the technician should ensure the vehicle is located in an area that has a clear unobstructed view of the open sky, and preferably, an area where analog, cellular calls have been successfully placed. These areas can be found by successfully making an OnStar® keypress in a known good OnStar® equipped vehicle and confirming success with the OnStar® Call Center advisor. Such places can be used as a permanent reference for future OnStar® testing.