Suspension Control System - Suspension Damping Cadillac STS I

Fastener Tightening Specifications

Fastener Tightening Specifications

Suspension Controls Schematic Icons

Suspension Controls Schematic Icons Icon Icon Definition IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)

Scheme 10

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Scheme 14

Suspension Controls Connector End Views

Electronic Suspension Control (ESC) Module Connector End Connector Part Information OEM: 54210060 Service: 48-Way F FCI (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function 1 RD/WH 2340 Battery Positive Voltage 2 BK 1050 Ground 3 WH/BK 1006 Right Front Strut Motor Increase Damping Control 4 OG 1010 Left Rear Strut Motor Increase Damping Control 5 - - Not Used 6 YE 321 Electronic Level Control Relay Output - Coil 7-12 - - Not Used 13 L-GN/WH 1216 Right Rear Strut Position Sensor Signal 14 L-GN/WH 1210 Left Rear Strut Position Sensor Signal 15 TN/WH 1213 Right Front Strut Position Sensor Signal 16 TN/WH 1207 Left Front Strut Position Sensor Signal 17 OG/BK 1448 Left Front Strut Motor Increase Damping 18 YE 1014 Right Rear Strut Motor Increase Damping 19 YE 5727 High Speed GMLAN Serial Data Wake Up 20 WH 320 Automatic Level Control Exhaust Solenoid Control 21 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 22 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 23-26 - - Not Used 27 OG/BK 1214 Right Rear Strut Position Sensor Voltage Reference 28 OG/BK 1208 Left Rear Strut Position Sensor Voltage Reference 29 PU/WH 1211 Right Front Strut Position Sensor Voltage Reference 30 PU/WH 1205 Left Front Strut Position Sensor Voltage Reference 31 L-GN 1005 Left Front Strut Motor Decrease Damping Control 32 BN 1007 Ride Control Strut Motor - Feed - Right Front - Decrease Damping 33 OG/BK 1013 Left Rear Strut Motor Decrease Damping Control 34 PU 1017 Right Rear Strut Motor Decrease Damping 35-38 - - Not Used 39 TN 2501 High Speed GMLAN Serial Data (-) (1) 40 TN 2501 High Speed GMLAN Serial Data (-) (1) 41-44 - - Not Used 45 L-GN/BK 1215 Right Rear Strut Position Sensor Low Reference 46 L-GN/BK 1209 Left Rear Strut Position Sensor Low Reference 47 L-BU/BK 1212 Right Front Strut Position Sensor Low Reference 48 L-BU/BK 1206 Left Front Strut Position Sensor Low Reference

Suspension Damper - LF Connector End Connector Part Information OEM: 15305168 Service: 12167117 2-Way F Metri-Pack 150 Series (GY) Suspension Damper Adapter OEM: 15359261 Service: 88953232 2-Way M Metri-Pack 150 Series (L-GY) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A OG/BK 1448 Left Front Strut Motor Increase Damping B L-GN 1005 Left Front Strut Motor Decrease Damping Control

Suspension Damper - LR Connector End Connector Part Information OEM: 15305168 Service: 12167117 2-Way F Metri-Pack 150 Series (GY) Suspension Damper Adapter OEM: 15359261 Service: 88953232 2-Way M Metri-Pack 150 Series (L-GY) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A OG 1010 Left Rear Strut Motor Increase Damping Control B OG/BK 1013 Left Rear Strut Motor Decrease Damping Control

Suspension Damper - RF Connector End Connector Part Information OEM: 15305168 Service: 12167117 2-Way F Metri-Pack 150 Series (GY) Suspension Damper Adapter OEM: 15359261 Service: 88953232 2-Way M Metri-Pack 150 Series (L-GY) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A WH/BK 1006 Right Front Strut Motor Increase Damping Control B BN 1007 Ride Control Strut Motor - Feed - Right Front - Decrease Damping

Suspension Damper - RR Connector End Connector Part Information OEM: 15305168 Service: 12167117 2-Way F Metri-Pack 150 Series (GY) Suspension Damper Adapter OEM: 15359261 Service: 88953232 2-Way M Metri-Pack 150 Series (L-GY) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A YE 1014 Right Rear Strut Motor Increase Damping B PU 1017 Right Rear Strut Motor Decrease Damping

Suspension Position Sensor - LF Connector End Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A PU/WH 1205 Left Front Strut Position Sensor Voltage Reference B TN/WH 1207 Left Front Strut Position Sensor Signal C L-BU/BK 1206 Left Front Strut Position Sensor Low Reference

Suspension Position Sensor - LF Connector End (Export w/TT7/TT8, w/o F55) Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A PU/WH 1205 Left Front Strut Position Sensor Voltage Reference B TN/WH 1207 Left Front Strut Position Sensor Signal C L-BU/BK 1206 Left Front Strut Position Sensor Low Reference

Suspension Position Sensor - LR Connector End Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A OG/BK 1208 Left Rear Strut Position Sensor Voltage Reference B L-GN/WH 1210 Left Rear Strut Position Sensor Signal C L-GN/BK 1209 Left Rear Strut Position Sensor Low Reference

Suspension Position Sensor - LR Connector End (Export w/TT7/TT8, w/o F55) Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A OG/BK 1208 Left Rear Strut Position Sensor Voltage Reference B L-GN/WH 1210 Left Rear Strut Position Sensor Signal C L-GN/BK 1209 Left Rear Strut Position Sensor Low Reference

Suspension Position Sensor - RF Connector End Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A PU/WH 1211 Right Front Strut Position Sensor Voltage Reference B TN/WH 1213 Right Front Strut Position Sensor Signal C L-BU/BK 1212 Right Front Strut Position Sensor Low Reference

Suspension Position Sensor - RR Connector End Connector Part Information OEM: 15326556 Service: 88953359 3-Way F GT 150 Series (BK) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe: Pin Wire Color Circuit No. Function A OG/BK 1214 Right Rear Strut Position Sensor Voltage Reference B L-GN/WH 1216 Right Rear Strut Position Sensor Signal C L-GN/BK 1215 Right Rear Strut Position Sensor Low Reference

Diagnostic Starting Point - Electronic Suspension Control

Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check - Vehicle 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 DTCs and their status

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

Scan Tool Output Controls

A scan tool may be used in order to command the shock absorbers ON or OFF, without the need for input information from other components. This can be very helpful in determining if a certain portion of a circuit or a component is in working order. The table below lists the tests that are available for the electronic suspension control system. The tests are listed in alphabetical order.

Using a scan tool, select the ESC Special Functions from the scan tool menu. The status of the output being cycled will be shown on the scan tool's display screen. The shock absorbers can be cycled to turn ON or OFF by selecting ESC Special Functions on the scan tool.

Using the LF shock absorber as an example, commanding the LF shock absorber ON can indicate whether the ESC system is able to correctly operate the LF shock absorber. This can determine if a DTC that pertains to that shock absorber is able to reset, and if the ESC module's internal circuitry is able to operate the LF shock absorber. For example, suppose the ESC system sets an intermittent DTC C0577, which is LF Shock Absorber Solenoid Short to Ground. In order to diagnose this condition using a scan tool, select the ESC special Functions. Then, cycle the LF shock absorber solenoid while moving the suspected wiring/connector. Attempt to duplicate the malfunction conditions. This scan tool feature allows checks that could not be performed while driving the vehicle. This example can be applied to the other shock absorbers.

Suspension Control Module

Scan Tool Data List

The ESC Scan Tool Data List contains all the electronic suspension control system related parameters that are available on the scan tool. The parameters in the list are arranged in alphabetical order. The column, "Data List," indicates the location of the parameter within the scan tool menu selections.

Use the ESC Scan Tool Data List as directed by a diagnostic table or in order to supplement the diagnostic procedures. Begin all of the diagnostic procedures with the Vehicle Diagnostic System Check.

Use the ESC Scan Tool Data List only after the following is determined

1. There is no published DTC procedure nor published symptom procedure for the customer concern.
2. The DTC or symptom diagnostic procedure indicated by the diagnostic system check does not resolve the customer concern.

The Typical Data Values are obtained from a properly operating vehicle under the conditions specified in the first row of the Scan Tool Data List table. Comparison of the parameter values from the suspect vehicle with the Typical Data Values may reveal the source of the customer concern.

A scan tool must be used in diagnosing system malfunctions before removing or replacing any of the components. Become familiar with the scan tool diagnostic capabilities and thoroughly understand each of the diagnostic features described before attempting any diagnostic procedures. The scan tool is capable of displaying data and input/output information from all of the systems connected to the serial data line. The scan tool is also capable of commanding the shock absorbers ON or OFF without the need for any input information.

Data Display

The scan tools input display function can be helpful in determining if the ESC module is receiving the correct input status. This can assist in determining if the ESC system is actually operating normally. For example, the ESC system requires the input from the position sensors in order to determine the ride settings. A starting point might be to select the LF position sensor data display function from the scan tool menu. The voltage status should change when the LF corner of the car is pressed down and released. If no change occurred, then the problem is possibly a disconnected link or a stuck sensor. If change did occur, then the problem is intermittent. In order to diagnose this condition using a scan tool, watch the data display for the LF position sensor while moving the suspected wiring/connector. Try to duplicate the malfunction conditions. This scan tool feature allows checks that could not be performed while driving the vehicle.

ESC Scan Tool Data List

ESC Scan Tool Data Definitions

The ESC Scan Tool Data Definitions contain a brief description of all the scan tool parameters. This list is in alphanumeric order.

Circuit Description

When the ignition switch is turned ON, the electronic suspension control (ESC) module monitors communications between its internal microprocessors and performs self-diagnostic tests. If an internal malfunction is detected, the ESC module will store a DTC C0550 in its memory.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC C0550 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 C0550

Conditions for Running the DTC

The ignition ON.

Conditions for Setting the DTC

1. The ESC module detected an internal malfunction.
2. The malfunction must be detected when the ignition switch is first turned ON.

Action Taken When the DTC Sets

1. Stores a DTC C0550 in the ESC memory
2. Disable all functionality
3. Sends a message to the instrument panel cluster (IPC) to display the SERVICE SUSPENSION SYSTEM message.

Conditions for Clearing the DTC

1. Under all fault conditions, the ignition must be cycled before this DTC can change from current to history.
2. The ESC module no longer detects any internal malfunctions when the ignition is first turned to the ON position.
3. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
4. Use the IPC clearing DTC feature.
5. Using a scan tool.

Diagnostic Aids

1. Since DTC C0550 is an internal malfunction to the ESC module, there is no repair procedure and the ESC module must be replaced.
2. The ESC module tests for multiple internal malfunctions and will store a DTC C0550 if one or more internal malfunctions are detected. Therefore, depending on which malfunction was detected, and what internal circuitry was affected, this DTC may cause various symptoms.

Test Description

The number below refers to the step number on the diagnostic table.

1. 2: This DTC requires ESC module replacement.

DTC C0550

The electronic suspension control (ESC) module performs checks of internal calibration data. If a fault condition is detected, the ESC module will set the fault DTC, and may, depending upon the fault type, turn on the SERVICE SUSPENSION SYSTEM message. Recovery from any controller fault condition is attempted only after the ignition is cycled ON and OFF.

This diagnostic procedure supports the following DTC

DTC C0558 Calibration Data Not Programmed

The ignition is ON.

1. The DTC is set when any calibration faults internal to the ESC module are detected.
2. The fault is detected during 3 consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with the scan tool.

1. Disable all functionality.
2. Sends a message to the instrument panel cluster (IPC) to display the SERVICE SUSPENSION SYSTEM message.

Conditions for Clearing the MIL/DTC

1. The scan tool can be used to clear the DTC.
2. The DTC is saved as HISTORY when the ESC module no longer senses the hardware fault and the ignition is cycled OFF and ON.

The number below refers to the step number on the diagnostic table.

1. 2: This step checks to see if the problem has cleared after the ESC module has been calibrated.

DTC C0558

The electronic suspension control (ESC) module uses the pulse-width modulation (PWM) method in order to control each shock absorber actuator. Switching the voltage ON and OFF at each shock absorber actuator, or pulse width modulating, limits the amount of current supplied to that particular actuator. The ESC module periodically commands each shock absorber to a set PWM duty cycle in order to override the normal PWM command. During this set PWM duty cycle, the ESC module is able to perform a diagnostic test on each shock absorber actuator, and can determine if a malfunction is present. The ESC module is only able to detect certain malfunctions during a given state, which are ON or OFF.

In order to test for the conditions that set a DTC C0575, C0580, C0585, or C0590, the ESC module must first command the actuator ON. The ESC module must be in a command ON state. If a low voltage level is detected in the actuator control circuit during the ON state, the test is again repeated. If the ESC module determines that the voltage levels detected in both tests are lower than expected, a malfunction is present and a DTC will set.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC C0575 Left Front Solenoid/Motor/Actuator Circuit
2. DTC C0580 Right Front Solenoid/Motor/Actuator Circuit
3. DTC C0585 Left Rear Solenoid/Motor/Actuator Circuit
4. DTC C0590 Right Rear Solenoid/Motor/Actuator Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0575, C0580, C0585, or C0590

The following conditions must be present to run the DTC

1. The ignition ON.
2. The ESC module in command ON state.
3. The ESC function enabled.

The ESC module detects a abnormal voltage level, which is a short to ground, open circuit or short to battery on the actuator control circuit during 2 diagnostic tests performed.

The following actions will occur when a DTC sets

1. Stores a DTC C0575, C0580, C0585 or C0590 in the ESC memory.
2. Commands 0 percent PWM duty cycle in order to disable all 4 actuators.
3. Sends a message to the instrument panel cluster (IPC) to display the SERVICE RIDE CONTROL message.
4. Sends a message to the powertrain control module (PCM) to limit the speed. The PCM then sends a message to the IPC to display the MAXIMUM SPEED 129 km/h (80 mph) message.

The following conditions must exist to clear the DTC

1. The ignition must be cycled before this DTC can change from current to history even if the malfunction is no longer present.
2. The ESC module no longer detects a abnormal voltage level, which is a short to ground, open circuit or short to battery on the actuator control circuit during two diagnostic tests.
3. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
4. Use the IPC clearing DTC feature.
5. Using a scan tool.

The following conditions may cause an intermittent malfunction to occur

1. There is an intermittent short to ground, open circuit or short to battery on the actuator control circuit.
2. There is an internal shock absorber actuator short.
3. If the conditions for a DTC C0575, C0580, C0585 or C0590 are current, the ESC module will disable all 4 actuators by commanding 0 percent duty cycle, and the RTD relay. The vehicle will experience a soft ride condition on the side of the vehicle.
4. The RTD relay provides supply voltage to all 4 shock absorber actuators; therefore, multiple shock absorber actuator DTCs which are open or short to ground may also be stored along with a DTC C0550. Always diagnose a DTC C0550 first before attempting to diagnose multiple shock absorber actuator DTCs.
5. If a short to ground is present on the actuator supply circuit, the RTD fuse will open and DTC C0550 may set.
6. If the DTC is a history DTC, the problem may be intermittent. Using a scan tool, cycle the shock absorber actuator while moving the wiring and the connectors. This can often cause the malfunction to occur.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests for short to ground and short to B+ on the control circuit.
2. 4: This step tests for continuity from the ESC module on the control circuit and the low reference circuit.

DTC C0575, C0580, C0585, or C0590

The electronic suspension control (ESC) module supplies 5 volts to the position sensors. The position sensors use the supplied 5 volts to produce an analog output range of 0-5 volts. The ESC module calculates vehicle suspension settings based upon the voltage levels received back from the position sensors. The ESC model monitors for an out of range condition.

This diagnostic procedure supports the following DTCs

1. DTC C0615 Left Front Position Sensor Circuit
2. DTC C0620 Right Front Position Sensor Circuit
3. DTC C0625 Left Rear Position Sensor Circuit
4. DTC C0630 Right Rear Position Sensor Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0615, C0620, C0625 or C0630

1. The ignition is ON.
2. The ESC function is enabled.

1. The ESC module senses position sensor output voltage under 0.35 or over 4.75 volts.
2. The condition must be detected for 1 second in 4 consecutive ignition cycles.
3. No activity on the position sensor when activity detected on 2 or more other position sensors.

1. Stores a DTC C0615, C0620, C0625, or C0630 in the ESC memory.
2. Command speed dependent damping system default AND command normal force signals to default state.
3. Sends a message to the instrument panel cluster (IPC) to display the SERVICE SUSPENSION SYSTEM message.

1. The ESC module senses the correct position sensor output voltage between 0.35-4.75 volts.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Use the IPC clearing DTC feature.
4. Using a scan tool

1. The following conditions may cause an intermittent malfunction to occur: There is an intermittent open or short in the position sensor circuit. Bent, disconnected, or damaged position sensor linkage.
2. When using a scan tool in order to read position sensor voltage, always make sure the vehicle is sitting with the full vehicle weight on its wheels. Measuring position sensor voltage with the vehicle raised and the wheels hanging may lead to incorrect diagnosis.
3. An intermittent DTC C0615, C0620, C0625 or C0630 may produce a random firm/soft ride condition.
4. The ESC module uses an ignition cycle counter diagnosis approach to set this DTC. This requires the ESC module to detect a malfunction 4 times before setting the DTC. To disable this feature, use a scan tool to clear all DTCs before performing diagnosis procedures.
5. If the DTC is a history DTC, the problem may be intermittent. Using a scan tool, monitor the position sensor voltage while test driving the vehicle or moving the wiring and connectors. This can often cause the malfunction to occur.

If the left front position sensor DTC symptom was 08 then allow 30 seconds for redetection following clear codes.

If the left front position sensor DTC symptom was 55 then redetection requires driving the vehicle.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests the position sensor signal voltage range using a scan tool. Normal signal voltage is between 1.5-3.5 volts.
2. 3: This step tests the position sensor signal voltage range using a scan tool with the sensor disconnected. Normal signal voltage range with the sensor disconnected is approximately 0 volts.
3. 4: This step tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
4. 5: This step tests for a short to voltage in the 5-volt reference circuit.
5. 6: This step tests for high resistance or an open in the ground circuit.
6. 11: This step tests for an open or high resistance in the position sensor ground circuit.

DTC C0615, C0620, C0625 or C0630

The electronic suspension control (ESC) module provides a common regulated power supply of about 5 volts to all of the position sensors. The ESC module monitors this power supply for a malfunction that could prevent it from correctly regulating the supply voltage.

This diagnostic procedure supports the following DTC

DTC C0696 Position Sensor Overcurrent (5-volt supply)

The ignition is ON.

1. The ESC module senses position sensor supply voltage under 4.5 volts or over 5.5 volts.
2. The condition must be detected for 1 second in 4 consecutive ignition cycles.

1. Stores a DTC C0696 in the ESC memory
2. Command speed dependent damping system default AND command normal force signals to default state.
3. Sends a message to the instrument panel cluster (IPC) to display the SERVICE SUSPENSION SYSTEM message

1. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
2. The ESC module senses the correct sensor supply voltage (4.5-5.5 volts).
3. The IPC clearing DTCs feature
4. Using a scan tool

1. The following conditions may cause an intermittent malfunction to occur: An intermittent short to ground is detected on any of the position sensor supply circuits. An intermittent short to voltage is detected on any of the position sensor supply circuits.
2. The ESC module uses a common power supply in order to provide voltage to all of the position sensors. Therefore, a position sensor overcurrent code may be set if a malfunction is detected on any position sensor supply circuit.
3. The ESC module uses an ignition cycle counter diagnostic approach to set this DTC. This requires the ESC module to detect the malfunction 4 times before setting the DTC. To disable this feature, use a scan tool to clear all DTCs before preforming diagnostic procedures.
4. If any position sensor supply circuit is shorted to ground, the scan tool will indicate all of the position sensor voltage readings as zero.
5. If any position sensor is shorted to voltage, the position sensor will still function properly and the scan tool will display a valid position sensor voltage reading.
6. An intermittent DTC C0696 may produce a random firm/soft condition.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This tests the position sensor signal voltage range using a scan tool. The scan tool will display 0 volts for all position sensors if any position sensor 5-volt reference circuit is shorted to ground.
2. 3: This tests if any position sensor is shorted to ground.
3. 4: This tests determines which position sensor is shorted to ground.
4. 5: Tests for a short to ground in the position sensor 5-volt reference circuits.
5. 6: Tests for a short to voltage in the position sensor 5-volt reference circuits.

DTC C0696

Voltage is supplied to the electronic suspension control (ESC) module in the battery positive voltage circuit and the ignition voltage circuit. The ESC module monitors the supplied voltage to determine if it is within a valid operating range.

This diagnostic procedure supports the following DTC

DTC C0895 Device Voltage

The ignition is ON.

The DTC is set when the battery voltage is outside the normal range of 9-15.5 volts.

Disable All Functionality

1. The scan tool can be used to clear the DTC.
2. The DTC is saved as history when the ESC module no longer sees battery voltage outside the normal range of 9-15.5 volts. The DTC will clear if the fault does not return after 50 consecutive ignition cycles.

DTC C0895 may set when the vehicle is placed on a battery charger, on fast charge, for a long period of time. It may also be set by an intermittent charging system malfunction.

The numbers below refer to the step numbers on the diagnostic table.

1. 1: This test determines whether the malfunction is in the supply voltage or the ESC module.
2. 2: Checks for high resistance, a short to ground, or an open in the battery positive voltage circuit.

DTC C0895

Removal Procedure

1. Remove the right rear trim panel.
2. Loosen the electronic suspension control (ESC) module nuts (3)
3. Disconnect the ESC module electrical connector (1).
4. Remove the ESC module (2).

Installation Procedure

1. Install the ESC module (2).
2. Connect the ESC module electrical connector (1).
3. Tighten the ESC module nuts (3). Tighten: Tighten the nuts to 9 N.m (80 lb in).
4. Install the right rear trim panel.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/cadillac/sts/i-2004-2007/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
3. Disconnect the front ride sensor link from the upper control arm ball stud.
4. Disconnect the front ride sensor harness connector.
5. Loosen the front ride sensor retaining nut.
6. Gently tap the front ride sensor retaining stud in order to loosen the stud to fender connection.
7. Remove the front ride sender from the vehicle.

1. Position the sensor to the vehicle.
2. Install the front ride sensor retaining nut. Tighten: Tighten the nut to 9 N.m (80 lb in).
3. Connect the front ride sensor link to the upper control arm ball stud.
4. Connect the front ride sensor harness connector.
5. Install the tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/cadillac/sts/i-2004-2007/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
6. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/sts/i-2004-2007/remont/hoistjack/#general-information) in General Information.
2. Remove the tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/cadillac/sts/i-2004-2007/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
3. Disconnect the ride sensor link from the upper control arm ball stud.
4. Disconnect the ride sensor harness connector.
5. Loosen the rear ride sensor retaining nut.
6. Gently tap the rear ride sensor retaining stud in order to loosen the stud to frame connection.
7. Remove the rear ride sender from the vehicle.

1. Install the sensor to the vehicle.
2. Bottom out the captured stud in the key hole.
3. Rotate the sensor and bracket until the tab on the bracket bottoms out in the slot.
4. If the sensor bracket is not yet level, continue to rotate it allowing the captured stud to lift slightly from the bottom of the keyhole, until the sensor is level.
5. Install the rear ride height sensor retaining nut. Tighten: Tighten the nut to 9 N.m (80 lb in).
6. Connect the ride sensor link to the upper control arm ball stud.
7. Connect the ride sensor harness connector.
8. Install the tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/cadillac/sts/i-2004-2007/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
9. Lower the vehicle.

Electronic Suspension Control Description

The Electronic Suspension Control system, also known as the Magneto-Rheological Real Time Damping (MRRTD) system independently controls the fluid viscosity in each of the four shock absorbers in order to control the vehicle ride characteristics. The ESC system is capable of making these changes within milliseconds. The ESC system consists of the following major components

1. The electronic suspension (ESC) module
2. The front/rear position sensors
3. The front/rear adjustable shock absorbers
4. The shock absorber electrical actuators, which are integrated within the shock absorbers.

The ESC controls the damping mode selection according to the following factors

1. The vehicle speed
2. The chassis pitch input
3. The steering position
4. The body to wheel displacement

The ESC module evaluates these inputs in order to separately control the shock absorbers, providing an enhanced ride and comfort level over the widest possible range of operating conditions.

Electronic Suspension Control Module

The ESC module provides electronic control logic and output drive for each shock absorber. The ESC module makes decisions due to road and driving conditions based on various inputs. The ESC module receives input information by sensors that are directly connected to the ESC module or by other systems through the serial data line.

The ESC module uses these inputs in order to independently control the shock absorbers at each corner. The ESC module is located in the LH rear storage.

Electronic Suspension Control Position Sensors

The ESC position sensors provide the ESC module with the body to wheel displacement input. The ESC module uses this and other inputs in order to control the stiffness of the shock absorber. If any body or wheel motion is detected, the ESC module will determine how soft or firm each shock absorber should be to provide the best ride. The ESC position sensors are mounted at each corner of the vehicle between the control arm and the body.

Electronic Suspension Control Shock Absorber or Strut

The ESC shock absorbers are monotube type which provide damping by increasing magnetic flux to magnetic particles to resist suspension movement. The ESC shock absorber has the capability of providing multiple modes or values of damping forces, in both compression and rebound direction. The damping forces are achieved by increasing or decreasing the magnetic flux to shock absorbers.

The front ESC actuator connector is located at the top of the shock absorber. The rear ESC actuator connector is at the top of the shock absorber. The rear shock absorbers have jumper harnesses for ease of maintenance.

Electronic Suspension Control Operation

The ESC system uses the information from other systems in order to execute certain functions.

The ESC system does not have a malfunction indicator lamp, but instead uses the Instrument Panel Cluster (IPC) for the display functions. When the ESC system detects a malfunction that sets a DTC, the ESC system sends a message on the serial data line directly or through the PCM to the IPC, which will display one of the following messages

1. SHOCKS INOPERATIVE
2. SERVICE RIDE CONTROL
3. MAXIMUM SPEED 129 km/h (80 mph)

The SHOCKS INOPERATIVE message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all four shock absorbers. The ESC system will send a message on the serial data line to the IPC to display this message.

The SERVICE RIDE CONTROL message will only be displayed if the ESC system detects any malfunction that sets a DTC. The ESC system will send a message on the serial data line to the IPC to display this message.

The MAXIMUM SPEED message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all four shock absorbers. The ESC system will send a message on the serial data line to the PCM indicating that all four shock absorbers were disabled. The PCM then sends a message to the IPC to display this message.

The ESC module has the ability to store diagnostic trouble codes (DTCs) as current or history codes. Most ESC system malfunctions will display a message in the IPC and set a DTC. The message will remain ON until the RESET button is pressed on the Driver Information Center (DIC). As long as the DTC is current, the message will be displayed after every ignition cycle and the RESET button must be pressed to bypass the message.

The ESC system uses an ignition cycling diagnostic approach in order to reduce the occurrence of false or intermittent DTCs that do not affect the functionality of the ESC system. This allows for the fail-soft actions to be taken whenever a malfunction condition is current, but requires the malfunction to be current for a certain number of ignition cycles before the corresponding malfunction code and message will be stored or displayed.

If the ESC detects a malfunction, the ESC system defaults with a fail-soft action. A fail-soft action refers to any specific action the ESC system takes in order to compensate for a detected malfunction. A typical ESC fail-soft action would be if the ESC system detects a malfunction with a shock absorber, the ESC system will ignore this input and fail-soft to the TOUR ride setting.

It is possible for a suspension position sensor to become stuck. This fault would not be detected by the ESC module, therefore a DTC would not be set and no message would be displayed by the IPC. This fault is addressed under Symptoms - Electronic Suspension Control.

See also:
• Diagnostic System Check - Vehicle
• DTC Symptom Description
• Control Module References
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Shock, Shock Component, and/or Spring Replacement
• Shock Absorber Replacement
• Battery Inspection/Test
• Fastener Notice
• Lifting and Jacking the Vehicle
• Tire and Wheel Removal and Installation
• Suspension Controls Schematics
• Suspension Controls Connector End Views