GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Seville 🢒 DTC 🢒 DTC C1786 Damper Control Relay Fault

Circuit Description
Object Number: 305509 Size: LF

The high-side (battery) voltage for the CVRSS damper actuators is supplied to the CVRSS module through the CVRSS Damper Control Relay circuit. The Damper Control Relay circuit is controlled by the CVRSS module. The CVRSS module monitors the relay drive circuit and each damper actuator high-side and low-side drive circuits for fault conditions.

DTC C1786 is used to detect a fault condition with the damper control relay contacts and associated wiring.

Conditions for Setting the DTC

The DTC is set when there is a loss of battery voltage on pin D1 of the CVRSS module.

The DTC turns HISTORY when the CVRSS module senses a battery voltage at pin D1 after the ignition has been cycled.

Action Taken When the DTC Sets
    • ALL the damper actuators will be disabled by commanding 0 % PWM duty cycle. The vehicle ride will be soft.
    • The vehicle speed will be limited.
    • The SERVICE RIDE CONTROL message will be displayed.

Conditions for Clearing the MIL/DTC
    • Use the scan tool.
    • Use the On-Board diagnostic CLEAR RSS CODES feature.

Test Description

Important: 

   • Do not backprobe the sensors, actuators, or any sealed connectors.
   • When all the diagnostics and repairs are complete, clear the DTCs and verify the operation.

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks the contacts of the relay for proper operation.

    2.

  2. This step checks circuit 1333 for an open circuit condition.

Step

Action

Value(s)

Yes

No

1

Was the Road Sensing Suspension Diagnostic System Check performed?

--

Go to Step 2

Go to Road Sensing Suspension Diagnostic System Check

2

Is DTC C1787 or C1788 set?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 3

3

  1. Turn the ignition ON with the engine off.
  2. Backprobe from CVRSS module connector C1, terminal D1, to ground with a J 39200 DMM.

Is the voltage greater than the specified value?

10 V

Go to Step 9

Go to Step 4

4

  1. Disconnect CVRSS control module connector C1.
  2. Check for continuity between rear junction block connector C3, terminal A8, and CVRSS control module connector C1, terminal D1 (harness side), with a DMM.

Is there continuity?

--

Go to Step 5

Go to Step 8

5
  1. Turn the ignition OFF.
  2. Remove the Damper relay.
  3. Measure the voltage at the right front damper relay terminal of the Rear Junction Block

Is the voltage greater than the specified value?

10 V

Go to Step 7

Go to Step 6

6

Repair the the poor connection condition or open circuit condition in the power circuit to the Damper relay.

Refer to Wiring Systems, Power Distibution.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

7

Replace the Damper relay.

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

8

Repair the open circuit condition in CKT 1333.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

9

Check for an intermittent open in CKT 1333.

Was an intermittent open found?

--

Go to Step 10

Go to Step

10

Repair the intermittent open in CKT 1333.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

11

Check Damper relay for intermittent operation.

Does the Damper relay operate intermittently?

--

Go to Step 7

Go to Step 12

12
  1. Replace the CVRSS control module. Refer to Electronic Suspension Control Module Replacement .
  2. Install all of the connectors and components that were removed.
  3. Install the scan tool.
  4. Turn the ignition ON with the engine off.

    5. Important: The controller must be calibrated.

  5. Calibrate the CVRSS service controller using the scan tool. Refer to Electronic Suspension Control Module Calibration .

Is the CVRSS control module calibrated?

--

Go to Road Sensing Suspension Diagnostic System Check

--