GM SPO Group Numbers
| Application | GM SPO Group Number |
|---|---|
| Power Steering Control Module | 6.605 |
GM SPO Group Numbers
Scheme 1
Steering Controls Components
| Name | Location |
|---|---|
| Data Link Connector (DLC) | Attached to the I/P carrier, to the left of the steering column |
| Electronic Brake/Traction Control Module (EBTCM) | LH front of the engine compartment, mounted to the lower rail |
| Fuse Block | Mounted to the I/P, lower LH side of the steering column |
| Power Steering Control Module | Underneath the LH side of the I/P |
| Power Steering Fluid Flow Control Valve Actuator | Attached to the power steering gear |
| C200A | I/P wiring harness to body wiring harness, at the lower LH A-pillar |
| G103 | Body and I/P wiring harnesses, located at the LH front of the engine compartment, near C102, C105, and C106 |
| P103 | Lower LH A-pillar, forward to G200 |
| P110 | Rear LH corner of the engine compartment |
| S210 | I/P wiring harness, near the multifunction relay K134 connector branch break off |
| S212 | I/P wiring harness, near the multifunction relay K134 connector branch break off |
| S222 | I/P wiring harness, near G201 branch break off |
| S252 | I/P wiring harness, near G201 branch break off |
| S267 | Body wiring harness, near G200 branch break off |
STEERING CONTROLS COMPONENTS
Scheme 2
- 1 Multifunction Relay K134
- 2 Passenger Seat Heater Relay K56
- 3 Driver Seat Heater Relay K55
- 4 Power Steering Control Module
Power Steering Control Module
Pin Wire Color Circuit No. Function 1 BRN/WHT XM88 Serial data 2 BLK/PPL FY102 Fluid control valve actuator signal 3 -- -- NOT USED 4 BLU/RED PA12 Vehicle speed signal 5 BLK/GRY FR4 Fluid control valve actuator signal 6 BRN X83 IGN 7 -- -- NOT USED 8 BLK F88 Ground to G103 9 -- -- NOT USED
Power Steering Fluid Flow Control Valve Actuator
Pin Wire Color Circuit No. Function 1 BLK/GRY FR4 Actuator signal HI 2 BLK/PPL FY102 Actuator signal LO
Variable Effort Steering System Check
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | 1. Connect the scan tool to the data link connector (DLC). 2. Turn the ignition switch to the ON position. Do not start the engine. 3. Attempt to establish communication with the power steering control module. Does the scan tool communicate with the power steering control module? | Go to Step 3 | Go to Step 2 | |
| 2 | Go to SCAN TOOL DOES NOT COMMUNICATE WITH POWER STEERING CONTROL MODULE . Did you complete the repair or replacement? | Go to Step 4 | ||
| 3 | Use the scan tool to read the power steering control DTCs. Does the scan tool display any current DTCs? | Go to DTC INDEX | Go to Step 5 | |
| 4 | 1. Drive the vehicle above 24 km/h (15 mph) for several minutes. 2. Connect the scan tool to the data link connector (DLC). 3. Turn the ignition switch to the ON position. Do not start the engine. 4. Use the scan tool to read the power steering control DTCs. Does the scan tool display any current DTCs? | Go to DTC INDEX | Go to Step 5 | |
| 5 | Are there any history DTCs stored in memory? | Go to Step 6 | System OK | |
| 6 | 1. Review the appropriate DTC diagnosis table for the history DTC. 2. Review the diagnostic aids and the conditions for setting the DTC. 3. Review the procedures in TESTING FOR INTERMITTENT AND POOR CONNECTIONS Did you complete any repairs? | System OK |
VARIABLE EFFORT STEERING SYSTEM CHECK
Diagnostic Trouble Code (DTC) List
| DTC | Description |
|---|---|
| 21 | No Speed Signal |
| 22 | Solenoid Circuit Short to Ground/Open |
| 23 | Power Steering Control Module Malfunction |
DIAGNOSTIC TROUBLE CODE (DTC) LIST
Variable Effort Steering Diagnosis
A variable effort steering electrical system malfunction causes the power steering fluid flow actuator to default to a full restriction. A full restriction increases the steering effort. Refer to Variable Effort Steering System Check if the vehicle is experiencing this condition.
A mechanical/hydraulic steering system malfunction causes the loss of power steering at all times and/or objectionable noises
Refer to TESTING if a mechanical or a hydraulic malfunction of the pump or the steering gear is suspected
Scheme 3
Circuit Description
The electronic brake/traction control module (EBTCM), transmits a processed vehicle speed signal (VSS) from terminal 23 to terminal 4 of the power steering control module (PSCM). The PSCM uses the speed signal and the characteristic curve programmed in the microprocessor to determine the electric current variable for the power steering fluid flow control valve actuator
Conditions for Setting the DTC
The power steering control module detects that the vehicle speed signal (VSS) is no longer present at terminal 4
Action Taken When the DTC Sets
- Power steering assist will default to partial manual steering
- The PSCM will store a DTC 21 in memory
Conditions for Clearing the DTC
- Conditions for the fault are no longer present
- Using the scan tool.
Diagnostic Aids
Check for the following conditions if a history or intermittent DTC is indicated
- A poor connection at the PSCM. Inspect the harness connectors for backed out terminals, improper mating, improperly formed or damaged terminals, and poor terminal to wire connections
- A damaged wiring harness. Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the circuits. A change in the DMM display during this test will indicate the location of the fault
- For additional information, refer to «TESTING FOR INTERMITTENT AND POOR CONNECTIONS»(/cadillac/catera/i-1996-2001/remont/body-electrical/#testing-wiring-systems-for-intermittent-poor-connections)
The number(s) below refer to the step number(s) on the diagnostic table. There is no information omitted.
- 2. This step checks to see if the speedometer is operating properly
- 3. This step checks for the speed signal input into the power steering control module
- 5. This step replaces the power steering control module
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Was the Variable Effort Steering System Check performed? | Go to Step 2 | Go to Variable Effort Steering System Check | |
| 2 | Does the speedometer operate properly? | Go to Step 3 | Go to SPEEDOMETER/ODOMETER INOPERATIVE in ANALOG INSTRUMENT PANELS - CATERA. | |
| 3 | 1. Disconnect the power steering control module connector. 2. Raise the drive wheels. 3. Turn the ignition switch to the ON position. 4. Use the DMM, on the AC scale, to measure the voltage between terminals 4 and 8 of the power steering control module connector while rotating the LH rear wheel. Is the measured voltage within the specified value? | Greater than 1 VAC | Go to Step 5 | Go to Step 4 |
| 4 | 1. Locate an open or a high resistance in circuit PA12. 2. Repair the open or the high resistance in circuit PA12. Is the repair complete? | Go to Step 6 | ||
| 5 | Replace the power steering control module. Refer to Power Steering Control Module Replacement Is the replacement complete? | Go to Step 6 | ||
| 6 | 1. Connect all connectors and components that were disconnected. 2. Road test the vehicle. 3. After road test, install the scan tool again. 4. Check for DTC 21. Is DTC 21 present? | Go to Variable Effort Steering System Check | System OK |
DTC 21 NO SPEED SIGNAL
Scheme 4
The power steering control module (PSCM) determines current flow of the power steering fluid flow control valve actuator (solenoid) which is relative to the vehicle speed
The solenoid converts the electrical signal into a corresponding hydraulic control variable, which determines the amount of reaction pressure and thus the steering force
- Short to ground or open in CKTs FR4 (BLK/GRY) or FY102 (BLK/PPL).
- A defective power steering control valve actuator
- Power steering assist will default to partial manual steering effort
- The PSCM will store a DTC 22 in memory
- Conditions for the fault are no longer present
- Using the scan tool
Check for the following conditions if a history or intermittent DTC is indicated
- A poor connection at the PSCM. Inspect the harness connectors for backed out terminals, improper mating, improperly formed or damaged terminals, and poor terminal to wire connections
- A damaged wiring harness. Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the actuator. A change in the DMM display during the test will indicate the location of the fault.
- For additional information, refer to «TESTING FOR INTERMITTENT AND POOR CONNECTIONS»(/cadillac/catera/i-1996-2001/remont/body-electrical/#testing-wiring-systems-for-intermittent-poor-connections)
Test Description
The number(s) below refer to the step number(s) on the diagnostic table. There is no information omitted.
- 3. This test checks for an open circuit in the wiring and control valve actuator windings
- 6. This test checks for a short to ground in both circuit FY102 and FR4
- 8. Before replacing the module, check the power and ground circuits
- 10. This step determines after all repair attempts and DTC 22 is still present, that an internal malfunction exists in the Power Steering Control Module
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Was the Variable Effort Steering System Check performed? | Go to Step 2 | Go to Variable Effort Steering System Check | |
| 2 | 1. Connect the scan tool to the data link connector (DTC). 2. Check for a current DTC 22. Is a current DTC 22 displayed? | Go to Step 3 | Go to Step 4 | |
| 3 | 1. Remove the power steering control module (PSCM). 2. Use a DMM to measure the resistance across terminals 2 and 5 of the module connector. Is the measured resistance within the specified value? | 7-8 ohms | Go to Step 6 | Go to Step 7 |
| 4 | Check for a history or an intermittent DTC 22. Is a history or an intermittent DTC 22 displayed? | Go to Step 5 | Go to Step 6 | |
| 5 | 1. Locate an intermittent in circuits FR4 and/or FY102. 2. Repair the intermittent in circuits FR4 and/or FY102. Is the repair complete? | Go to Step 10 | ||
| 6 | 1. Use the DMM to measure the resistance between terminal 2 of the PSCM connector and a known good ground. 2. Use the DMM to measure the resistance between terminal 5 of the PSCM connector and a known good ground. Is the measured resistance for both measurements within the specified value? | OL | Go to Step 8 | Go to Step 9 |
| 7 | 1. Locate an open or a high resistance in circuits FR4 and/or FY102. 2. Repair the open or the high resistance in circuits FR4 and/or FY102. 3. Replace the power steering fluid flow control valve actuator if these circuits are OK. Is the repair or replacement complete? | Go to Step 10 | ||
| 8 | 1. Check power and ground circuits to the module. 2. Replace the power steering control module if power and ground is OK. Refer to Power Steering Control Module Replacement Is the replacement complete? | Go to Step 10 | ||
| 9 | 1. If any continuity readings were observed, locate a short to ground in circuits FR4 and/or FY102. 2. Repair the short to ground in circuits FR4 and/or FY102. Is the repair complete? | Go to Step 10 | ||
| 10 | 1. Connect all connectors or components that were disconnected. 2. Road test the vehicle. 3. After the road test, install the scan tool again. 4. Check for DTC 22. Is DTC 22 displayed? | Go to Variable Effort Steering System Check | System OK |
DTC 22 SOLENOID CIRCUIT SHORT TO GROUND/OPEN
Circuit Operation
As part of its normal processing, the power steering control module (PSCM) performs data checks to RAM on a continious basis. Certain data is stored in RAM until it is summoned by the microprocessor or superseded by more recent data. Data stored in RAM is erased when the system is switched off
DTC 23 is an internal PSCM fault (RAM defect).
Power steering assist will default to partial manual steering effort
Replacing the power steering control module.
- Before replacing the PSCM, test the power circuit (BRN wire) and ground circuit (BLK wire).
- Perform a voltage drop test when testing the power and ground circuit. Refer to Testing for Voltage Drop in Wiring Systems
The number(s) below refer to the step number(s) on the diagnostic table. There is no information omitted.
- 2. This step checks for the proper voltage to the module. Proper voltage is needed by the module to operate properly
- 4. This step checks for the proper ground to the module. A proper ground is needed by the module to operate properly
- 6. This step replaces the power steering control module
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Was the Variable Effort Steering System Check performed? | Go to Step 2 | Go to Variable Effort Steering System Check | |
| 2 | 1. Remove the power steering control module (PSCM). 2. Turn the ignition switch to the ON position. 3. Use a DMM to measure the voltage between terminal 6 of the PSCM connector and a known good ground. Is the measured voltage within the specified value? | B+ | Go to Step 4 | Go to Step 3 |
| 3 | 1. Locate an open or a high resistance in circuit X83. 2. Repair the open or the high resistance in circuit X83. Is the repair complete? | Go to Step 7 | ||
| 4 | Use the DMM to measure the resistance between terminal 8 of the PSCM connector and a known good ground. Is the measured resistance within the specified value? | Less than.5 ohms | Go to Step 6 | Go to Step 5 |
| 5 | 1. Locate an open or a high resistance in circuit F88. 2. Repair the open or the high resistance in circuit F88. Is the repair complete? | Go to Step 7 | ||
| 6 | Replace the power steering control module. Is the replacement complete? | Go to Step 7 | ||
| 7 | 1. Connect all of the connectors and components that were disconnected. 2. Road test the vehicle. 3. Install the scan tool after the road test. 4. Check for DTC 23. Is DTC 23 displayed? | Go to Variable Effort Steering System Check | System OK |
DTC 23 POWER STEERING CONTROL MODULE MALFUNCTION
Removal Procedure
| CAUTION | This vehicle is equipped with a Supplemental Inflatable Restraint (SIR) System. Failure to follow the correct procedure could cause the following conditions: Air bag deployment Personal injury Unnecessary SIR system repairs In order to avoid the above conditions, observe the following guidelines: Refer to COMPONENT LOCATION for SIR Component Views in order to determine if you are performing service on or near the SIR components or the SIR wiring If you are performing service on or near the air components or wiring, see COMPONENT LOCATION or SUPPLEMENTAL RESTRAINTS wiring, disable the SIR system. Refer to DISABLING & ACTIVATING AIR BAG SYSTEM |
Scheme 5
- Twist the self-locking screws to allow for the front of the sound insulator to drop down to remove the sound insulator
- Remove the power steering control module (1) from the electrical connector
Scheme 6
- Install the power steering control module (1) to the electrical connector
- Twist the self-locking screws to attach the sound insulator to the instrument panel to install the sound insulator
Variable Effort Steering Description
The Variable Effort Steering (VES) system varies the driver effort required to steer the vehicle at different speeds. At low speeds the system provides maximum power assist for ease of turning and for parking maneuvers. At higher speeds increased steering effort will provide the driver with firmer steering (road feel) and directional stability
The VES system reduces the power steering fluid flow from the pump as the vehicle speed increases. The system provides maximum fluid flow when the vehicle is stationary. The fluid flow decreases as the vehicle speed increases
The power steering control module uses the vehicle speed input from the Electronic Brake Traction Control Module/Brake Pressure Modulator Valve (EBTCM/BPMV).
Input from the EBTCM/BPMV to the power steering control module causes an appropriate change in the power steering fluid flow control valve actuator
The power steering fluid flow control valve actuator is mounted on the steering gear. The power steering fluid flow control valve actuator utilizes a pintle valve to control the fluid flow
The system defaults to a full restriction in the event of a failure. A full restriction results in stiffer than normal steering at lower speeds