GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Suspension 🢒 Road Sensing Suspension (RSS) 🢒 DTC C1787 Damper Control Relay Short to GND

Object Number: 258353 Size: LF

Circuit Description

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

Conditions for Setting the DTC

The DTC is set when the CVRSS control module measures a feedback voltage less than a preset threshold during a damper relay OFF state.

The DTC turns HISTORY when the CVRSS control module no longer senses a low feedback voltage during a damper relay OFF state.

Action Taken When the DTC Sets
    • ALL the damper actuators may be disabled by commanding 0 % PWM duty cycle. The vehicle ride may be soft.
    • The vehicle speed may be limited.
    • The SERVICE RIDE CONTROL message may 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 for a blown RSS fuse.

    2.

  2. This step checks for an open circuit condition in CKT 2240

    3.

  3. This step checks the resistance of the relay coil.

    4.

  4. This step checks for an open circuit condition in CKT 1112.

    5.

  5. This step checks for a short circuit to ground condition in CKT 1112.

    6.

  6. This step checks for a short circuit to ground condition in CKTs 2240 and 998.

Step

Action

Value(s)

Yes

No

1

Was the CVRSS System Check performed?

--

Go to Step 2

Go to Road Sensing Suspension Diagnostic System Check

2

Check the RSS 20 Amp for a blown (open) condition. The RSS 20 Amp fuse (HOT AT ALL TIMES) is located in the rear compartment fuse block.

Is the fuse blown (open)?

--

Go to Step 7

Go to Step 3

3

  1. Install the RSS 20 Amp fuse (HOT AT ALL TIMES)
  2. ignition OFF.
  3. Remove the RTD BODY relay.
  4. Measure the voltage between pin B5 of the RTD BODY relay socket (harness side) and ground.

Is the measurement greater than the specified value?

10 V

Go to Step 4

Go to Step 10

4

Measure the resistance between pin B7 and pin C5 of the RTD BODY relay (device side).

Is the measurement within the specified values?

50-125 ohms

Go to Step 5

Go to Step 12

5

  1. Disconnect CVRSS control module connector C1.
  2. Check for an open circuit condition or a poor connection in CKT 1112.

Is an open circuit or poor connection condition present?

--

Go to Step 11

Go to Step 6

6

Check for a short circuit (continuity) to ground in CKT 1112.

Is a short circuit to ground condition present?

--

Go to Step 15

Go to Step 8

7

  1. Disconnect CVRSS control module connector C1.
  2. Check for a short circuit (continuity) to ground condition in CKTs 2240 (qty 2), 1333, 1107, 1114, 1116, and 1118.

Is a short circuit to ground condition present?

--

Go to Step 9

Go to Step 13

8
  1. Check all connections on CKTs 2240 and 1112 for debris, corrosion, and/or intermittent open circuit conditions. Refer to Intermittents and Poor Connections .
  2. Check CKT 1112 for intermittent short circuit to ground conditions.
  3. Install all of the connectors and/or components that were removed.
  4. Clear the DTCs. Refer to Clearing DTCs .
  5. Check the DTCs. Refer to Displaying Diagnostic Trouble Codes (DTC) .

Is DTC C1787 set?

--

Go to Step 14

Go to Road Sensing Suspension Diagnostic System Check

9

Repair the short circuit to ground condition in the affected circuit.

Is the repair complete?

--

Go to Step 13

--

10

Repair the open circuit condition in CKT 2240.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

11

Repair the open circuit condition in CKT 1112.

Is the repair complete?

--

Go to the Road Sensing Suspension Diagnostic System Check

--

12

Replace the RTD BODY Relay.

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

13

Replace the RSS 20 Amp fuse (HOT AT ALL TIMES).

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

14
  1. Turn the ignition OFF.
  2. Replace the CVRSS control module. Refer to Electronic Suspension Control Module Replacement .
  3. Install all of the connectors and components that were removed.
  4. Install the scan tool.
  5. Turn the ignition ON with the engine off.

    6. Important: The controller must be calibrated.

  6. 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

--

15

Repair the short circuit to ground condition in CKT 1112.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--