Computer/integrating Systems: Other Cadillac STS I

Action Taken When the DTCs Sets

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the GMLAN serial data circuits.
3. The module inhibits the setting of all other GMLAN communication DTCs.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) Inoperative

Retained Accessory Power (RAP) Inoperative

Control Module References

Control Module References

Data Link References

This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. Some modules may have multiple communication circuits passing through them without actively communicating on that data link. This table is used to assist in correcting a communication malfunction. For the description and operation of these serial data communication circuits refer to Data Link Communications Description and Operation .

Data Link References

Setup New IPM/RIM

This procedure will allow the user to compare the IPM and rear integration module (RIM) vehicle configuration data. The IPM is the master for storing vehicle configuration and a backup copy is retained in the RIM. If a fault occurs in either module, this test will do a comparison of data and the user will then be able to update the data in the module that was replaced.

To set up a new IPM, perform 'Setup New IPM/RIM' procedure under Vehicle Control Systems > Computer/Integrating Systems > Module Setup > IPM menus on the scan tool.

Excepting the Export Country option, which is slightly different, the screen will display 4 columns. The user will be able to scroll up and down with the up and down arrow keys in all columns. The user will be able to scroll through options available to that name/function in the fourth column with the left and right arrow keys. The first column will display the function of the option. The second column will display RIM data and the third column will display IPM data. The forth and final column will display all options available for that name/function. The user will compare the RIM to the IPM data or the IPM to the RIM data depending on which module was replaced. If the user replaces the IPM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the RIM column. Likewise, if the user replaces the RIM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the IPM column.

The following options can be set up

1. Export Country
2. Engine Type
3. Aux. Heater/KA6
4. TVT/YQ6 or YQ7 - TV Tuner
5. DRR/U2K - Digital Radio Receiver
6. Remote Start
7. Theft Export/CU9
8. CTD Present - Content Theft Deterrent (UK)
9. Automatic Trans.
10. AWD/MV3 - ACC Wheel Drive
11. Alarm Export/UA2
12. ACC/K59 - Adaptive Cruise Control
13. Driver Position
14. MSM Lumbar/AL2 - Memory Seat Module
15. MSM/A45 - Memory Seat Module
16. Intru Export/UA2 - Intrusion Sensor
17. Heated Seats/KA1
18. Speed Biasing
19. HUD/UV6 - Head Up Display
20. Incli Exp/UA2 - Inclination Sensor
21. VCIM/UE1 - OnStar®
22. SCLM/UA2 - Steering Column Lock Module
23. RWD/M22 or M82 - Rear Wheel Drive
24. SOD/UEB - Side Object Detection
25. ESC/F55 - Electronic Suspension Control
26. Overspeed /Warn.
27. TCS - Traction Control System
28. TPM - Tire Pressure Monitoring
29. Smart Beam /TQ5
30. Headlamp Level
31. Air Quality /K14
32. HV Seat /KB6 - Heated/Vented Seat
33. Metric FE Units - Fuel Economy Units
34. DRL/Z49 - Daytime Running Lamps
35. HID/TT6/TT7/TT8 - High Intensity Discharge Lamps
36. Fog Lmps not Us /Can
37. SWC/K59 - Steering Wheel Control Switches with Adaptive Cruise Control
38. SWC/UE1 - with OnStar®
39. SWC Htd St WHL - with Heated Steering Wheel

After all options were set, save them using Save Options. If the option setting was successfully, Procedure Complete message will be displayed. The power mode will toggle from Run to Accessory.

Program VIN

This procedure needs to be performed if IPM is replaced. Under Module Setup > IPM menu, perform the program VIN procedure following the Tech 2 instructions.

This procedure will allow the user to compare the IPM and rear integration module (RIM) vehicle configuration data. The IPM is the master for storing vehicle configuration and a backup copy is retained in the RIM. If a fault occurs in either module, this test will do a comparison of data and the user will then be able to update the data in the module that was replaced.

To set up a new IPM, perform 'Setup New IPM/RIM' procedure under Vehicle Control Systems > Computer/Integrating Systems > Module Setup > IPM menus on the scan tool.

Excepting the Export Country option, which is slightly different, the screen will display 4 columns. The user will be able to scroll up and down with the up and down arrow keys in all columns. The user will be able to scroll through options available to that name/function in the fourth column with the left and right arrow keys. The first column will display the function of the option. The second column will display RIM data and the third column will display IPM data. The forth and final column will display all options available for that name/function. The user will compare the RIM to the IPM data or the IPM to the RIM data depending on which module was replaced. If the user replaces the IPM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the RIM column. Likewise, if the user replaces the RIM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the IPM column.

The following options can be set up

1. Export Country
2. Engine Type
3. Aux. Heater/KA6
4. TVT/YQ6 or YQ7 - TV Tuner
5. DRR/U2K - Digital Radio Receiver
6. Remote Start
7. Theft Export/CU9
8. CTD Present - Content Theft Deterrent (UK)
9. Automatic Trans.
10. AWD/MV3 - ACC Wheel Drive
11. Alarm Export /UA2
12. ACC/K59 - Adaptive Cruise Control
13. Driver Position
14. MSM Lumbar/AL2 - Memory Seat Module
15. MSM/A45 - Memory Seat Module
16. Intru Export /UA2 - Intrusion Sensor
17. Heated Seats/KA1
18. Speed Biasing
19. HUD/UV6 - Head Up Display
20. Incli Exp /UA2 - Inclination Sensor
21. VCIM/UE1 - OnStar®
22. SCLM/UA2 - Steering Column Lock Module
23. RWD/M22 or M82 - Rear Wheel Drive
24. SOD/UEB - Side Object Detection
25. ESC/F55 - Electronic Suspension Control
26. Overspeed/Warn.
27. TCS - Traction Control System
28. TPM - Tire Pressure Monitoring
29. Smart Beam/TQ5
30. Headlamp Level
31. Air Quality/K14
32. HV Seat/KB6 - Heated/Vented Seat
33. Metric FE Units - Fuel Economy Units
34. DRL/Z49 - Daytime Running Lamps
35. HID/TT6/TT7/TT8 - High Intensity Discharge Lamps
36. Fog Lmps not Us/Can
37. SWC/K59 - Steering Wheel Control Switches with Adaptive Cruise Control
38. SWC/UE1 - with OnStar®
39. SWC Htd St WHL - with Heated Steering Wheel

After all options were set, save them using Save Options. If the option setting was successfully, Procedure Complete message will be displayed. The power mode will toggle from Run to Accessory.

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector (DLC).
3. Turn the ignition ON, with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

Data Link Connector (DLC)

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

1. Scan tool power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5
4. Low speed GMLAN serial data bus at terminal 1
5. High speed GMLAN serial data bus (+) at terminal 6
6. High speed GMLAN serial data bus (-) at terminal 14

High Speed GMLAN Serial Data Line

The GMLAN serial data communications circuit on this vehicle is in a linear topology. The following modules are connected to the link, in order from data link connector (DLC) to the end of the linear configuration

1. The instrument panel module (IPM)
2. The electronic suspension control (ESC) module, with F85
3. The communication interface module (OnStar), with UE1
4. The dynamic headlamp leveling (DHL) device, with TR7
5. The electronic brake control module (EBCM)
6. The transmission control module (TCM)
7. The engine control module (ECM)

The distance sensing and cruise control (DSCC) module, with K59 option, it is connected to the high speed GMLAN bus through splice pack SP100. Refer to Data Link Connector (DLC) Schematics for more information.

The OnStar module doesn't functionally communicate on the high speed GMLAN bus. It is connected to high speed GMLAN bus for remotely diagnostic purposes.

Low Speed GMLAN Serial Data Line

The low speed GMLAN serial data communication circuit on this vehicle is in a star configuration. The star has 3 splice packs, located as follows

1. The splice pack SP201 is located under the left side of the instrument panel (I/P), near the data link connector (DLC).
2. The splice pack SP300 is located next by the left B-pillar.
3. The splice pack SP303 is located next by the right B-pillar.

The following modules communicate on the low speed GMLAN serial data circuit

1. The splice pack SP201 attaches to: The instrument panel module (IPM) The head-up display (HUD), with UV6 The HVAC control module The instrument panel cluster (IPC) The radio The steering column lock control module (SCLCM), with UA2
2. The splice pack SP300 attaches to: The audio amplifier The driver door module (DDM) The driver door switch (DDS) is attached to DDM The driver position module (DPM), with A45 The digital radio receiver (DRR), with U2K The inflatable restraint sensing and diagnostic module (SDM) The left rear door module (LRDM) The rear integration module (RIM) The remote control lock door receiver (RCDLR) The television (TV) module, with YK6/YK7
3. The splice pack SP303 attaches to: The communication interface module (OnStar), with UE1 The inflatable restraint SDM The passenger door module (PDM) The right rear door module (RRDM)

Refer to Data Link Connector (DLC) Schematics for more information.

Gateway

The instrument panel module (IPM) is the gateway between low speed and high speed GMLAN serial data circuits. The purpose of the gateway is to transfer serial data messages from one subnet to another. The IPM shall unpack the signals from frames received from one bus that are to be transmitted across the gateway and repack the signals into frames to be transmitted on the other bus. The IPM shall be responsible for data passing only. The data passed from one bus to the other shall in no way be modified by the IPM gateway function. The IPM receives 3 distinct types of messages on a given bus

1. Signals the IPM uses for internal functional applications
2. Signals the IPM uses for internal functional applications and are passed from one bus to the other bus
3. Signals the IPM does not use for internal functional applications but are passed from one bus to the other bus

Power Mode

The IPM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.

Load Management

The power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharge condition. This is accomplished by using a high accuracy battery voltage and current reading by a current sensor as an indicator of battery discharge rate. The following 6 levels of load management will execute in the load management control algorithm when there is a high discharge condition

1. The first action requests a vehicle idle speed increase to the engine control module (ECM) in order to raise alternator output.
2. The second action requests a greater vehicle idle speed increase to the ECM in order to raise alternator output.
3. The third action begins to shed vehicle loads in an attempt to remedy the heavy discharge condition.
4. The fourth action requests another vehicle idle speed increase to the ECM in order to raise further the alternator output.
5. The fifth action begins to shed further vehicle loads in an attempt to remedy the heavy discharge condition.
6. If the above 5 corrective actions fail, the sixth action of power management further sheds loads in a final attempt to remedy the high discharge condition.

Loads subject to reduction include the following

1. The A/C clutch
2. The heated mirrors
3. The heated seats
4. The rear defog
5. The HVAC blowers
6. The interior lighting

For more information about load shedding, refer to Load Shed System Description and Operation in Engine Electrical.

Each load management function, either idle boost or load-shed, is discrete. No 2 functions are implemented at the same time. During each load management function, the power mode master (PMM) checks the battery temperature, battery voltage and amp-hour calculations and determines if the PMM should implement a different power management function.

Regulator Voltage Control (RVC)

Regulator voltage control (RVC) will result in the battery being charged at its optimum voltage for improved battery life and state of charge (SOC), fuel economy and lamp life by lowering the system voltage when the SOC is high. The electrical power management (EPM) algorithm in the instrument panel module (IPM) will determine the optimum charging voltage, based on estimates of its SOC and battery electrolyte temperature. Optimum charge voltage is defined as the battery charge voltage that results in maximum battery life, while maintaining energy storage for engine starting, discharge at idle, and parasitic loads. The optimum battery charge voltage will be converted to a percent duty cycle command that will be sent to the ECM via serial data link. The ECM will then place the 128 Hz pulse width modulation (PWM) duty cycle on the L line.

Other IPM Functions

The instrument panel module (IPM) performs multiple body control functions. The IPM can control devices directly connected to its outputs based on input information. The IPM evaluates this information and controls certain body control systems by commanding outputs on or off. The IPM inputs can be

1. Sensors and switches that are directly connected to the IPM
2. GMLAN serial data messages received from other vehicles systems connected to the low or high speed GMLAN serial data links

The IPM is also capable of controlling other vehicle systems that are not directly wired to the IPM, through serial data messages. Some of the functions that the IPM controls or contributes to, are

1. Audible warnings - Refer to «Indicator/Warning Message Description and Operation»(ref-197555-S41726676052005101200000) in Instrument Panel, Gages, and Console.
2. Column lock - Refer to «Steering Wheel and Column Description and Operation»(ref-197546-S21821242412005101200000) in Steering Wheel and Column.
3. Exterior lighting control and BASS - Refer to «Exterior Lighting Systems Description and Operation»(ref-197547-S02329781852005101200000) in Lighting Systems.
4. Interior lighting - Refer to «Interior Lighting Systems Description and Operation»(ref-197547-S39973713422005101200000) in Lighting Systems.
5. Headlamp washer - Refer to «Headlamp Washer System Description and Operation»(ref-197570-S01097168962005101200000) in Wipers/Washer Systems.
6. Horn control - Refer to «Horns System Description and Operation»(ref-197536-S13796628912005101200000) in Horns.
7. Park brake switch - Refer to «Park Brake System Description and Operation»(ref-197581-S20544280242005101200000) in Park Brake.
8. Personalization - Refer to «Personalization Description and Operation»(ref-197558-S38656618392005101200000) in Personalization.
9. Retained accessory power - Refer to «Retained Accessory Power (RAP) Description and Operation»(ref-197535-S24734388112005101200000) .
10. Remote start - Refer to «Starting System Description and Operation»(ref-197559-S17103611762005101200000) in Engine Electrical.
11. Steering wheel control switches - Refer to «Radio/Audio System Description and Operation»(ref-197539-S01781598412005101200000) in Entertainment and «Cruise Control Description and Operation (Adaptive Cruise Control)»(ref-197544-S18909061442005101200000) or «Cruise Control Description and Operation (Conventional Cruise Control)»(ref-197544-S12181850422005101200000) in Cruise Control.
12. Traction control switch - Refer to «ABS Description and Operation»(ref-197552-S05723381582005101200000) in Antilock Brake System.

Rear Integration Module (RIM)

The various rear integration module (RIM) inputs and outputs are described in the corresponding functional areas as indicated on the RIM electrical schematics. The RIM functions include the following

1. Content theft deterrent - Refer to «Content Theft Deterrent (CTD) Description and Operation»(ref-197565-S29438557032005101200000) in Theft Deterrent.
2. Interior lighting - Refer to «Interior Lighting Systems Description and Operation»(ref-197547-S39973713422005101200000) in Lighting Systems.
3. Exterior lighting - Refer to «Exterior Lighting Systems Description and Operation»(ref-197547-S02329781852005101200000) in Lighting Systems.
4. Theft deterrent - Refer to «Content Theft Deterrent (CTD) Description and Operation»(ref-197565-S29438557032005101200000) in Theft Deterrent.
5. Rear defogger - Refer to «Rear Window Defogger Description and Operation»(ref-197534-S07569626382005101200000) in Stationary Windows.
6. Rear park assist chime control - Refer to «Object Detection Description and Operation»(ref-197563-S28091307402005101200000) in Rear Parking Assist.
7. Sunroof control - Refer to «Sunroof Description and Operation»(ref-197597-S31940837312005101200000) in Roof.

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the instrument panel module (IPM). The IPM will monitor the ignition mode switch only with battery voltage above 7 volts to prevent invalid input readings during low voltages encountered during vehicle cranking. If the ignition mode switch input or the battery voltage input changes, a ratiometric calculation of ignition mode switch input value is performed. The IPM discerns the following states over the ignition mode switch signal circuits

1. Switch inactive
2. Switch stuck
3. Start button active
4. Off/Acc button active
5. Ignition mode switch signal circuit short to ground
6. Ignition mode switch signal circuit short to B+

To determine the correct power mode the IPM uses

1. The ignition mode switch data received from the ignition mode switch
2. The status of the engine run flag (ERF)

The following power modes are transmitted on both low speed and high speed GMLAN serial data circuits

1. Off-Awake
2. Accessory
3. Run
4. Crank

The accessory power mode times out after 20 minutes and the power mode becomes Off-Awake.

The following outputs are controlled by IPM as part of the power moding task

1. Accessory voltage, active in Accessory and Run power modes.
2. Run Ignition 3 voltage, active in a remote start request and in Run power mode.
3. Run/Crank Ignition 1 voltage, active in a remote start request and in Run and Crank power modes.
4. Engine control module (ECM)/transmission control module (TCM) serial data wake-up, active in a remote start request and in all power modes when IPM is awake except Crank.
5. High speed GMLAN serial data wake up, active in a remote start request and in all power modes when IPM is awake.

Serial Data Messages

If no power mode message can be received, the modules remain in the last power mode received and check for the ERF message. If the ERF serial data is true, indicating that the engine is running, the modules fail-safe to Run power mode. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is false, indicating that the engine is not running, the modules fail-safe to Off-Awake power mode and shut down after a while if no other conditions require them to be awake.

Discrete Power Mode Signals

Those modules that have Run/Crank signal inputs also remain in the state dictated by the last valid power mode message from the IPM or the RCDLR. They then check the state of their Run/Crank Ignition 1 voltage input to determine the current valid state. If the discrete ignition input is active, the modules will fail-safe to the Run power mode. If the discrete ignition input is inactive, the modules will fail-safe to Off-Awake power mode and shut down after a while if no other conditions require them to be awake.

ECM and TCM Power Mode Backup Strategy

The ECM and TCM remain in the last known power mode state until it can determine its backup system power mode based on their discrete Accessory voltage and Run/Crank Ignition 1 voltage inputs.

Power Mode Description and Operation

Serial Data Control of Retained Accessory Power (RAP)

Retained accessory power (RAP) permits the operation of some devices after the ignition switch is turned OFF. These selected items will remain in operation until any of the front passenger doors is opened or until the RAP function timer reaches its shut-off limit, which is 10 minutes. The instrument panel module (IPM) monitors the ignition mode signal from the ignition mode switch, battery condition and the front doors status to determine whether RAP should be initiated.

RAP will end when one of the following conditions is met

1. The IPM receives information about the opening of the driver or the front passenger door.
2. The RAP timer expires.
3. The battery capacity decreases below a prescribed limit.
4. Any other ignition switch state is chosen.

The functions supported in the RAP power mode are

1. The power windows
2. The instrument panel cluster (IPC) and driver information center (DIC) displays
3. The entertainment devices
4. The sunroof

The sunroof operation is allowed when sunroof enable signal circuit from rear integration module (RIM) to sunroof module is active. The circuit is activated by RIM anytime, in all power modes, except Off-Awake. In Off-Awake power mode, the sunroof enable signal circuit is activated by RIM for the RAP period.