Suspension - Electronic (Computer Command Ride) Cadillac Seville IV

DESCRIPTION & OPERATION

Computer Command Ride (CCR) system automatically controls the firmness of vehicle ride. CCR control module, located on instrument panel right sound insulator, controls an electric actuator in each strut. The actuator rotates a selector valve which has 3 differently sized orifices. The position of the selector valve affects the firmness of the strut damping characteristics. (Scheme 33) CCR control module monitors driver selection, vehicle speed and lateral acceleration, and then positions the selector valve to adjust ride firmness accordingly.

Scheme 33

CONTROL MODULE

The CCR control module is a computer used exclusively to control and monitor the CCR system. It is located on a bracket under the package shelf in the trunk. The control module receives speed, lift/dive and lateral acceleration switch input and determines the optimum mode strut valving for current operating conditions. The control module also receives feedback from the struts to determine proper system operation. If the control module receives an incorrect feedback signal an error code will be set in CCR memory and a "SERVICE CCR SYSTEM" message will be displayed on the Driver Information Center. For diagnostic purposes, grounding the Diagnostic Enable circuit will cause a Light Emitting Diode (LED) on the control module to flash error codes.

STRUT

The strut contains an electrical actuator which rotates a selector valve to a specific location commanded by the control module. The selector valve contains different sized orifices which will increase or decrease the damping rate of the strut to control ride firmness. Actuators are an integral part of the strut and are not serviceable from the strut.

VEHICLE SPEED

Vehicle speed affects ride firmness. (Scheme 34)

LIFT/DIVE INPUT

Lift/Dive input is received from the Powertrain Control Module (PCM). The system goes to the Firm mode during wide open throttle to provide anti-lift. The system will also go to the Firm mode when a high deceleration rate is seen to provide anti-dive.

LATERAL ACCELERATION

The lateral acceleration switch is used to provide the CCR control module with body roll information. The CCR control module will command struts to the Firm mode when lateral acceleration is sensed.

Scheme 34

FEEDBACK VOLTAGE

Each actuator provides a feedback voltage signifying actuator position relative to a "Home" position. A single 3.0 volt pad signifies the home position which correlates to the first Comfort damping position of the actuator, while subsequent 0 - 1.0 volt pad signify the remaining damping positions. Each damping position is separated by a 5.0 volt pad.

ERROR LAMP

When the ignition switch is turned on the system performs a self test which lasts for 7.5 seconds. The error lamp will be on for this period. After the self test, the control module may be in one of the following modes

1. Normal operating mode - the error lamp in on below 10 mph and goes off above 10 mph to indicate proper operation of the CCR system and to verify that the control module is receiving speed information.
2. Error Mode - The error lamp is off below 10 mph and turns on above 10 mph.
3. Reset Mode - The error lamp is turned off to indicate a CCR" control module problem.

Any system error will cause a "SERVICE CCR SYSTEM" message to be displayed on the Driver Information Center. The message will be displayed as long as the error code is active. If the fault corrects itself, the "SERVICE CCR SYSTEM" message will turn off, but the error code will be retained in the control module memory.

Error codes are stored in the control module in non-volatile memory. In diagnostics, the error codes are read via the LED by grounding the Diagnostic Enable circuit an counting the LED flashes.

If a code is set, a one second self diagnostic test is performed at three minute intervals. The error lamp will be on during this test and will go out if the fault is corrected. If the fault still exists, the lamp will be off below 10 mph and on above 10 mph.

Retrieving Codes

The CCR diagnostic system may be actuated by grounding the Diagnostic Enable circuit at pin C of the ALDL connector or by grounding pin D2 to D16 of the control module connector. After pin C is grounded, the lamp will be on for 7.5 seconds before beginning the blink code diagnostic sequence. This is followed by displaying code 12, three times to mark the beginning of the sequence. Then each stored error code is blinked out, in ascending order. Each code is displayed three times before proceeding to the next code. When all codes have been read, the entire code sequence will repeat, starting by blinking code 12, three times. The sequence will repeat until the Diagnostic Enable circuit is disconnected.

Codes are read by counting the number of flashes of the LED on the CCR control module. A code 12 would be indicated by the lamp flashing once, followed by a one second pause, followed by a one second pause, followed by a two flashes with a half second pause between flashes. There is a three second pause between codes.

If the diagnostic mode is entered, and no codes are stored in memory, the control module will continually display code 12.

Error Codes

The computer command ride system has the ability to display the following diagnostic codes in the CODE DEFINITION TABLE .

CODE DEFINITION

Clearing Codes

The error codes can be cleared by grounding the diagnostic enable circuit (pin C to pin A of the ALDL connector or pin D2 to D16 of the control module connector) three times (for approximately one second duration each) within 30 seconds. The control module indicates codes clear by turning the error lamp off for one second. The codes are not cleared when the battery or control module connectors are disconnected.

Continuous Strut Cycling

Grounding the Diagnostic Enable circuit through a 6.6k +/- 1k ohm resistor causes the system to enter a continuous cycling mode. The module will continuously cycle the actuators from comfort to Firm to normal, at the rate of one change every 2 seconds, and check for errors. If a fault exists with a strut, that strut will not cycle until a retest is performed. If the fault has cleared prior to the 3 minute retest, the strut will cycle when the retest is complete.

Strut Connectors

Strut connectors are attached to the top of the strut tenon w/locking tabs. To remove the connector, squeeze the tabs and lift the connector vertically.

In order to maintain the sealing integrity of the connector, strut connectors should be disconnected from the strut only when necessary. When strut connectors are removed for service or diagnosis, before reconnecting, be certain that the connector cavity in the strut is clean and dry, and the connector seal are in the proper position.

Intermittent Codes

Since many intermittent conditions are caused at electrical connections, diagnosis of intermittent conditions should include a visual and physical inspection of the connectors involved in the circuit. These connectors should be examined before replacing any components of the system. Some causes of connector problems are

1. Corrosion, moisture or other foreign matter in the strut cavity or on the terminal mating surfaces which could insulate the terminals.
2. Incomplete mating of the connector halves.
3. Damaged terminals or connector bodies.

CCR System Check, Flow Chart. Scheme 35

Computer Command Ride Message Circuit. Scheme 36

Description

If the control module loses any of the following inputs, a "SERVICE CCR SYSTEM" message will display, but no codes will be set

1. Power (Message displayed under 10 mph only)
2. Message signal (Message displayed under 10 mph only)
3. Speed signal (Message displayed over 10 mph only)
4. System ground

Service CCR System Message Displayed No Codes Set. Scheme 37

Test Conditions

The control module will check individual actuator current draw.

Fault Conditions

If the actuator motor start-up current exceeds 1.5 amps, set code.

Action Taken

Record actuator over current error, Turn on "SERVICE CCR SYSTEM" message, Disable actuator for 10 seconds, retest every 3 minutes.

Following an actuator repositioning command the actuators are energized at intervals of 12.5 milliseconds to allow individual actuator startup current monitoring. The system current is monitored before each actuator is turned on and one millisecond after turn on, these values are subtracted to determine the actuator startup current. An actuator startup current in excess of 1.5 amps results in an error code 13, a disabling of the faulted actuator, and an activation of the "SERVICE CCR SYSTEM" message. The system will continue to operate all non faulted actuators normally.

Note On Intermittents

Actuator over current conditions may occur as a result of moisture, corrosion, or foreign material in the strut cavity.

Code 13, Schematic, Left Front Actuator Over Current. Scheme 38

Code 13, Flow Chart, Left Front Actuator Over Current. Scheme 39

The control module will check individual actuator current draw.

If the actuator motor start-up current exceeds 1.5 amps, set code.

Record actuator over current error, Turn on "SERVICE CCR SYSTEM" message, Disable actuator for 10 seconds, retest every 3 minutes.

Following an actuator repositioning command the actuators are energized at intervals of 12.5 milliseconds to allow individual actuator startup current monitoring. The system current is monitored before each actuator is turned on and one millisecond after turn on, these values are subtracted to determine the actuator startup current. An actuator startup current in excess of 1.5 amps results in an error code 14, a disabling of the faulted actuator, and an activation of the "SERVICE CCR SYSTEM" message. The system will continue to operate all non faulted actuators normally.

Actuator over current conditions may occur as a result of moisture, corrosion, or foreign material in the strut cavity.

Code 14, Schematic, Right Front Actuator Over Current. Scheme 40

Code 14, Flow Chart, Right Front Actuator Over Current. Scheme 41

The control module will check individual actuator current draw.

If the actuator motor start-up current exceeds 1.5 amps, set code.

Record actuator over current error, Turn on "SERVICE CCR SYSTEM" message, Disable actuator for 10 seconds, retest every 3 minutes.

Following an actuator repositioning command the actuators are energized at intervals of 12.5 milliseconds to allow individual actuator startup current monitoring. The system current is monitored before each actuator is turned on and one millisecond after turn on, these values are subtracted to determine the actuator startup current. An actuator startup current in excess of 1.5 amps results in an error code 15, a disabling of the faulted actuator, and an activation of the "SERVICE CCR SYSTEM" message. The system will continue to operate all non faulted actuators normally.

Actuator over current conditions may occur as a result of moisture, corrosion, or foreign material in the strut cavity.

Code 15, Schematic, Left Rear Actuator Over Current. Scheme 42

Code 15, Flow Chart, Left Rear Actuator Over Current. Scheme 43

The control module will check individual actuator current draw.

If the actuator motor start-up current exceeds 1.5 amps, set code.

Record actuator over current error, Turn on "SERVICE CCR SYSTEM" message, Disable actuator for 10 seconds, retest every 3 minutes.

Following an actuator repositioning command the actuators are energized at intervals of 12.5 milliseconds to allow individual actuator startup current monitoring. The system current is monitored before each actuator is turned on and one millisecond after turn on, these values are subtracted to determine the actuator startup current. An actuator startup current in excess of 1.5 amps results in an error code 16, a disabling of the faulted actuator, and an activation of the "SERVICE CCR SYSTEM" message. The system will continue to operate all non faulted actuators normally.

Actuator over current conditions may occur as a result of moisture, corrosion, or foreign material in the strut cavity.

Code 16, Schematic, Right Rear Actuator Over Current. Scheme 44

Code 16, Flow Chart, Right Rear Actuator Over Current. Scheme 45

CODE 23 - LEFT FRONT ACTUATOR POSITION ERROR

CCR control module monitors actuator position voltage for correct feedback sequence during an actuator move. A fault is detected if actuator position feedback sequence is incorrect or if more than 6 seconds is required to complete an actuator move.

When this occurs, CCR control module records error (sets appropriate code), turns on select switch LEDs and disables faulted actuator. CCR control module then performs a one-second test of system every 3 minutes until all faults (conditions which set code) are cleared. If actuator passes one of these tests, CCR control module will again command faulted actuator to operate.

A mismatch of commanded feedback signal and actual feedback signal which occurs after 6 seconds will not be detected as an error. Actuators will not be repositioned until CCR system commands a new actuator position as a result of new inputs from vehicle speed signal (ECM), lateral accelerator switch or select switch or until a 3-minute retest occurs.

If Code 23 sets intermittently, problem may be caused by extremely cold ambient temperatures (-40°F or less) which affect viscosity of strut fluid. Increased viscosity index may prevent actuator from moving within 6 seconds, setting a false code. Codes may also set intermittently because of poor electrical connections, especially at strut connector.

Scheme 46

Scheme 47

CODE 24 - RIGHT FRONT ACTUATOR POSITION ERROR

CCR control module monitors actuator position voltage for correct feedback sequence during an actuator move. A fault is detected if actuator position feedback sequence is incorrect or if more than 6 seconds is required to complete an actuator move.

When this occurs, CCR control module records error (sets appropriate code), turns on select switch LEDs and disables faulted actuator. CCR control module then performs a one-second test of system every 3 minutes until all faults (conditions which set code) are cleared. If actuator passes one of these tests, CCR control module will again command faulted actuator to operate.

A mismatch of commanded feedback signal and actual feedback signal which occurs after 6 seconds will not be detected as an error. Actuators will not be repositioned until CCR system commands a new actuator position as a result of new inputs from vehicle speed signal (ECM), lateral accelerator switch or select switch or until a 3-minute retest occurs.

If Code 24 sets intermittently, problem may be caused by extremely cold ambient temperatures (-40°F or less) which affect viscosity of strut fluid. Increased viscosity index may prevent actuator from moving within 6 seconds, setting a false code. Codes may also set intermittently because of poor electrical connections, especially at strut connector.

Scheme 48

CODE 25 - LEFT REAR ACTUATOR POSITION ERROR

CCR control module monitors actuator position voltage for correct feedback sequence during an actuator move. A fault is detected if actuator position feedback sequence is incorrect or if more than 6 seconds is required to complete an actuator move.

When this occurs, CCR control module records error (sets appropriate code), turns on select switch LEDs and disables faulted actuator. CCR control module then performs a one-second test of system every 3 minutes until all faults (conditions which set code) are cleared. If actuator passes one of these tests, CCR control module will again command faulted actuator to operate.

A mismatch of commanded feedback signal and actual feedback signal which occurs after 6 seconds will not be detected as an error. Actuators will not be repositioned until CCR system commands a new actuator position as a result of new inputs from vehicle speed signal (ECM), lateral accelerator switch or select switch or until a 3-minute retest occurs.

If Code 25 sets intermittently, problem may be caused by extremely cold ambient temperatures (-40°F or less) which affect viscosity of strut fluid. Increased viscosity index may prevent actuator from moving within 6 seconds, setting a false code. Codes may also set intermittently because of poor electrical connections, especially at strut connector.

Scheme 49

CCR control module monitors actuator position voltage for correct feedback sequence during an actuator move. A fault is detected if actuator position feedback sequence is incorrect or if more than 6 seconds is required to complete an actuator move.

When this occurs, CCR control module records error (sets appropriate code), turns on select switch LEDs and disables faulted actuator. CCR control module then performs a one-second test of system every 3 minutes until all faults (conditions which set code) are cleared. If actuator passes one of these tests, CCR control module will again command faulted actuator to operate.

A mismatch of commanded feedback signal and actual feedback signal which occurs after 6 seconds will not be detected as an error. Actuators will not be repositioned until CCR system commands a new actuator position as a result of new inputs from vehicle speed signal (ECM), lateral accelerator switch or select switch or until a 3-minute retest occurs.

If Code 26 sets intermittently, problem may be caused by extremely cold ambient temperatures (-40°F or less) which affect viscosity of strut fluid. Increased viscosity index may prevent actuator from moving within 6 seconds, setting a false code. Codes may also set intermittently because of poor electrical connections, especially at strut connector.

Scheme 50

CODE 32 - LATERAL ACCELERATOR SWITCH ERROR

CCR control module monitors voltage level of lateral accelerator switch signal. If switch circuit is shorted to battery or ground or if it is open (disconnected or broken wire), CCR will detect an invalid voltage level. When this occurs, CCR control module records error (sets Code 32), turns on select switch LEDs and disables lateral accelerator switch input until a valid voltage level is detected.

Scheme 51

CODE 33 - DRIVER SELECT SWITCH INPUT ERROR

CCR control module monitors select switch for a valid combination of inputs. A valid combination of inputs exists when CCR control module detects a grounded condition at only one of 3 select switch terminals (C4, C5 or C6) and other 2 terminals are open (ungrounded).

If CCR control module detects an invalid combination (all 3 switch inputs are open or more than one terminal is grounded at same time for more than 3 seconds), it records error (sets Code 33) and turns on select switch LEDs. CCR control module then defaults to SOFT mode until a valid combination of switch inputs is detected.

Scheme 52

CODE 34 - VEHICLE SPEED SIGNAL ERROR

Note. For information on ECM Code 24, see appropriate G - TEST W/ CODES article in the ENGINE PERFORMANCE Section.

If CCR control module does not detect a vehicle speed signal within 20 seconds and it has received 5 or more inputs from lateral accelerator switch, it records error (sets Code 34) and turns on select switch LEDs. It then defaults to zero speed damping level (firm ride). If this code sets intermittently, check lateral accelerator switch circuit and ECM. Code may also set intermittently because of poor electrical connections.

Scheme 53

Computer Command Ride System Wiring Diagram. Scheme 54

Computer Command Ride System Wiring Diagram. Scheme 55

Computer Command Ride Code Playout. Scheme 56

Scheme 57

Scheme 58

See also:
• CODE DEFINITION TABLE