Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| Rear Integration Module (RIM) | ||
| Sunroof Enable | Outputs | Controls the sunroof enable circuit. |
| Remote Control Door Lock Receiver (RCDLR) | ||
| Run/Crank Relay | Controls the Run/Crank relay. | |
Scan Tool Output Controls
Scan Tool Data List
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| Instrument Panel Module (IPM) Operating Conditions: Ignition ON, Engine OFF | |||
| Steering Wheel Controls Return | Inputs | Counts | Varies |
| Battery Voltage Signal | Load Management | Volts | 12.5 |
| Accessory Relay Status | Outputs | On/Off | On |
| Run Relay Status | Outputs | On/Off | On |
| Run/Crank Relay Status | Outputs | On/Off | On |
| Start LED Duty Cycle | Outputs | % | Varies |
| Accessory LED Duty Cycle | Outputs | % | Varies |
| OFF LED Duty Cycle | Outputs | % | Varies |
| Rear Integration Module (RIM) Operating Conditions: Ignition ON, Engine OFF | |||
| Battery Voltage Signal | Data | Volts | 12.5 |
| Run/Crank Terminal Status | Inputs | Active/Inactive | Active |
| Sunroof Enable Command | Outputs | Enable/Disabled | Enable |
| Remote Control Door Lock Receiver (RCDLR) Operating Conditions: Ignition ON, Engine OFF | |||
| Battery Voltage Signal | Data | Volts | 12.5 |
| Ignition Mode Switch | Data | Volts | 12.5 |
| Ignition Mode Switch | Data | Idle, ACC/OFF, Run | Idle |
| Ignition Switch Fault | Data | No/Yes | No |
| Invalid Power Moding | Data | No/Yes | No |
| Back up Power Moding | Data | Inactive/Active | Inactive |
| Run/Crank Relay Command | Data | On/Off | Off |
| Run/Crank Relay Status | Data | On/Off | On |
| Driver/Passenger Door Module (DDM/PDM) Operating Conditions: Ignition ON, Engine OFF | |||
| Door Ajar Switch | Data | Door Closed/Door Ajar | Door Closed |
Scan Tool Data List
Circuit Description
The internal fault detection is handled inside the control module. No external circuits are involved.
DTC Descriptor
This diagnostic procedure supports the following DTC
DTC B1000 Electronic Control Unit (ECU) Performance
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
| DTC Symptom | DTC Symptom Descriptor |
|---|---|
| 00 | No Additional Information |
| 31 | General Checksum Error |
| 32 | General Memory Failure |
| 33 | Special Memory Failure |
| 34 | RAM Failure |
| 35 | ROM Failure |
| 36 | EEPROM Failure |
| 37 | Watchdog Processor Failure |
| 38 | Supervision Software Failure |
| 39 | Internal Electronic Failure |
DTC B1000
Conditions for Running the DTC
The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
Conditions for Running the DTCs
- Voltage supplied to the module is in the normal operating voltage range.
- The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTC
A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.
Conditions for Clearing the DTC
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Diagnostic Aids
- This DTC cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with GMLAN Device. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(ref-197535-S13200116172005101200000) .
- An intermittent condition is likely to be caused by a short on the GMLAN serial data circuits. Use the Scan Tool Does Not Communicate with GMLAN Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(ref-197535-S13200116172005101200000) .
Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.
This diagnostic procedure supports the following DTC
DTC U0002 Fewer Controllers On than Programmed
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
| DTC Symptom | DTC Symptom Descriptor |
|---|---|
| 00 | No Additional Information |
DTC U0002
- Voltage supplied to the modules is in the normal operating voltage range.
- The vehicle power mode requires serial data communication to occur.
- The DTC U0001 does not have a current status.
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTC Sets
The module uses a default value for the missing parameter.
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
- A poor connection at the inoperative module may cause this code to set.
- An improperly powered module may cause this code to set.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Did you record any DTC in the range of U0100-U0299? | Go to DTC U0100-U0299 | Go to Step 3 |
| 3 | Attempt to communicate with all modules on the vehicle. Refer to Data Link References for the list of modules and options. Were you able to communicate with all modules on the vehicle? | Go to Step 4 | Go to Step 6 |
| 4 | Disconnect the module that set DTC U0002 as current. Inspect the harness connectors of the module that is not communicating for poor connections and terminal tension at the following circuits: The battery positive voltage input circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The switched battery positive voltage supply circuits The ground circuits The high speed GMLAN serial data circuits Refer to the following: Control Module References for the applicable schematic Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 11 | Go to Step 5 |
| 5 | Replace the module that set the DTC U0002 as current. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | |
| 6 | Test the following circuits of the module that is not communicating for an open or a short to ground: The battery positive voltage input circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The switched battery positive voltage circuits Refer to the following: Control Module References for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
| 7 | Turn OFF the ignition. Test the ground circuits of the module that is not communicating for an open. Refer to the following: Control Module References for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 11 | Go to Step 8 |
| 8 | Test the high/low speed GMLAN serial data circuits of the module that is not communicating for an open. Refer to Circuit Testing and GMLAN Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 9 | Inspect the harness connectors of the module that is not communicating for poor connections and terminal tension at the following circuits: The battery positive voltage input circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The switched battery positive voltage supply circuits The ground circuits The high/low speed GMLAN serial data circuits Refer to the following: Control Module References for the applicable schematic Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 10 | Replace the module that is not communicating. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | |
| 11 | Use the scan tool in order to clear the DTCs. Does the scan tool still display other current DTCs? | Go to the Diagnostic System Check - Vehicle in Vehicle DTC Information | |
DTC U0002
Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.
DTC Descriptors
This diagnostic procedure supports the following DTCs
- DTC U0100 Lost Communication With Engine Control Module (ECM)
- DTC U0101 Lost Communication With Transmission Control Module (TCM)
- DTC U0104 Lost Communication With Distance Sensing and Cruise Control (DSCC) Module
- DTC U0121 Lost Communication With Electronic Brake Control Module (EBCM)
- DTC U0141 Lost Communication With Instrument Panel Module (IPM)
- DTC U0181 Lost Communication With Dynamic Headlamp Leveling (DHL) Control Module
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
| DTC Symptom | DTC Symptom Descriptor |
|---|---|
| 00 | No Additional Information |
DTC U0100-U0299
- Voltage supplied to the modules is in the normal operating voltage range.
- The vehicle power mode requires serial data communication to occur.
- The DTC U0001 does not have a current status.
A supervised periodic message that includes the transmitter module availability has not been received.
The module uses a default value for the missing parameter.
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
- A poor connection at the inoperative module may cause this code to set.
- An improperly powered module may cause this code to set.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Did you record any DTC in the range of U2105-U2199? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 |
| 3 | IMPORTANT: Use the DTC list in DTC Descriptors to determine which module is not communicating. Test the following circuits of the module that is not communicating for an open or a short to ground: The battery positive voltage input circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The switched battery positive voltage circuits Refer to the following: Control Module References for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 8 | Go to Step 4 |
| 4 | Turn OFF the ignition. Test the ground circuits of the module that is not communicating for an open. If the module is the body control module (BCM), test its class 2 serial data circuit for an open, also. Refer to the following: Control Module References for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 8 | Go to Step 5 |
| 5 | Test the high speed GMLAN serial data circuits of the module that is not communicating for an open. Refer to Circuit Testing and GMLAN Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 8 | Go to Step 6 |
| 6 | Inspect the harness connectors of the module that is not communicating for poor connections and terminal tension at the following circuits: The battery positive voltage input circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The switched battery positive voltage supply circuits The ground circuits The high speed GMLAN serial data circuits Refer to the following: Control Module References for the applicable schematic Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Did you find and correct the condition? | Go to Step 8 | Go to Step 7 |
| 7 | Replace the module that is not communicating. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 8 | |
| 8 | Use the scan tool in order to clear the DTCs. Does the scan tool still display other current DTCs? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| IMPORTANT |
|---|
| Use the DTC list in DTC Descriptors to determine which module is not communicating. |
DTC U0100-U0299
Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255 the controller removes itself from the network and a DTC U2100 will be set.
This diagnostic procedure supports the following DTC
DTC U2100 Controller Area Network (CAN) Bus Communication
This vehicle has DTCs which include DTC Symptoms. The DTC symptom descriptions for symptoms 71 and 72 are exceptions for this vehicle and differ from what is described on DTC Symptom Description. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
| DTC Symptom | DTC Symptom Descriptor |
|---|---|
| 00 | No Additional Information |
| 71 | Low Speed Bus Error |
| 72 | High Speed Bus Error |
DTC U2100
- Voltage supplied to the module is in the normal operating voltage range.
- The vehicle power mode requires serial data communication to occur.
A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.
- The module suspends all message transmission.
- The module uses default values for all parameters received on the GMLAN serial data circuits.
- The module inhibits the setting of all other GMLAN communication DTCs for the respective bus.
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the systems. Refer to «Checking Aftermarket Accessories»(ref-197533-S03944243902005101200000) in Wiring Systems.
- 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
- «Scan Tool Does Not Power Up»(ref-197535-S10840601132005101200000)
- «Scan Tool Does Not Communicate with High Speed GMLAN Device»(ref-197535-S13200116172005101200000)
- «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(ref-197535-S17368299612005101200000)
- «Retained Accessory Power (RAP) On After Timeout»(ref-197535-S24051442652005101200000)
- «Retained Accessory Power (RAP) Inoperative»(ref-197535-S07855423792005101200000)
The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following
- Scan tool power battery positive voltage at terminal 16
- Scan tool power ground at terminal 4
- Common signal ground at terminal 5
The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.
Scan Tool Does Not Communicate with High Speed GMLAN Device
Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications on the high speed GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC U0001 or U2100 will be set. These DTCs can be retrieved as history only.
The high speed GMLAN serial data bus uses two 120 ohms terminating resistors that are in parallel with the high speed GMLAN (+) and (-) circuits. One of the resistors is connected at the instrument panel module (IPM) and the other is at the engine control module (ECM). When testing for a short between high speed GMLAN (+) and (-) a reading of 60 ohms is normal. If the high speed GMLAN serial data is open testing the resistance between high speed GMLAN (+) and (-) will read about 120 ohms.
The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following conditions may cause a total loss of high speed GMLAN data communication
- A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
- Any of the high speed GMLAN serial data circuits shorted to ground or voltage
- A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
- Any of the high speed GMLAN serial data circuits open
Modules connected to the low speed GMLAN serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.
The communication among modules is performed through the low speed and high speed GMLAN serial data circuits. The modules that need real time communication are attached to the high speed GMLAN network. The instrument panel module (IPM) is the gateway between the networks. The purpose of the gateway is to transfer information from one network to another. The gateway will interact with each network according to that network's transmission model. Refer to Body Control System Description and Operation for more information about the gateway.
GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles's functionality has been requested. A virtual network is supported by virtual devices which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a "heartbeat" of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped on the Tech 2 screen as a code against the physical device. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.
High Speed GMLAN Circuit Description
The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on 2 twisted wires that allow speed up to 500 Kbps. The twisted pair is terminated with two 120 ohms resistors, one is internal to the engine control module (ECM) and the other is internal to the instrument panel module (IPM). The resistors are used to reduce noise on the high speed GMLAN bus during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level which is approximately 2.5 volts is considered a recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes adds 1 volt to high speed GMLAN serial data bus (+) and subtracts 1 volt from high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0.
Two different outputs are used by IPM to activate the high speed GMLAN bus
- Accessory wake up, active in all power modes when IPM is awake except Crank and in a remote start request
- High speed communication enable, active in all power modes when IPM is awake and in a remote start request
The accessory wake up signal wakes up the ECM and the transmission control module (TCM) only. This output is disabled in Crank power mode for internal fail enable of the ECM and TCM. The high speed communication enable signal wakes up all the other modules on the high speed GMLAN bus.
Low Speed GMLAN Circuit Description
The data link connector (DLC) allows a scan tool to communicate with the low speed GMLAN serial data circuit. The serial data is transmitted over a single wire to the appropriate control modules. The transmission speed for GMLAN low speed is up to 83.33 Kbps. This high speed is used for programming purposes only. Under normal vehicle operating conditions the speed of the bus is 33.33 Kbps. This protocol produces a simple pulse train sent out over the low speed GMLAN serial data bus. To wake up the control modules connected to the low speed GMLAN serial data bus, a wake-up pulse of 10 volts is sent out over the bus.