GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C Sierra - 2WD 🢒 Suspension 🢒 Real Time Damping (RTD) 🢒 DTC C0000

Circuit Description

The suspension control module receives a vehicle speed signal input from the powertrain control module via the vehicle speed signal circuit and also receives vehicle speed data over the serial data class 2 circuit. Once vehicle speed has been detected, the suspension control module compares the two inputs for accuracy.

Conditions for Running the DTC

Continuously after vehicle speed has been detected from one or both inputs.

Conditions for Setting the DTC

Class 2 vehicle speed is greater than 32 km/h (20 mph) and the calculated speed input (hard wire) is less than 5 km/h (3 mph) continuously for 10 seconds.

Action Taken When the DTC Sets
    • Disable EVO outputs.
    • Stores a DTC C0550 in the suspension control module memory.

Conditions for Clearing the DTC
    • The suspension control module detects a vehicle speed signal from the PCM of greater than 32 km/h (20 mph).
    • Using a scan tool.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

Diagnostic Aids

Important:  Calibrate the suspension control module before replacement and cycle the ignition off and on to see if the DTC C0550 resets.

The replacement suspension control module must be calibrated when replacement is necessary.

Test Description

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

  1. Tests whether the condition is module, system, or condition related.

    2.

  2. Tests whether the condition has been corrected or identified as specified in the supporting text.

    3.

  3. Tests for an open or short in the vehicle speed circuit of the suspension control module.

Step

Action

Yes

No

Schematic Reference: Suspension Controls Schematics

1

Did you perform the RTD Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Real Time Damping

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC information for DTC C0000 in the suspension control module.

Does the scan tool indicate that DTC C000 is current?

Go to Step 4

Go to Step 3

3

Since most occurrences of this DTC are caused by a short or open vehicle speed signal circuit to the suspension control module, review the RTD system operation or, with the customer to verify the conditions under which the DTC set.

Did the vehicle operation cause this DTC to set?

Go to Step 7

Go to Step 4

4

  1. Use the scan tool in order to clear the DTCs.

    2. Important: Do not cycle the ignition.

  2. Operate the vehicle within normal operating conditions.

Does the DTC reset?

Go to Step 5

System OK

5

Test the vehicle speed signal circuit of the suspension control module for a short to ground, short to voltage and an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Important: After replacement, use the scan tool to perform the set up procedure (re-calibrate) located under Special Functions (F8: Recalibration) for the suspension control module.

Replace the suspension control module. Refer to Electronic Suspension Control Module Replacement .

Did you complete the replacement?

Go to Step 7

--

7
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle (road test) within normal operating conditions.

Does the DTC reset?

Go to Step 2

System OK