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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Suspension 🢒 Real Time Damping (RTD) 🢒 DTC C1658 EEPROM Calibration Malfunction

Circuit Description

The RTD system calibrations are stored in the EEPROM. When the ignition switch is first turned to the ON position, the ESC module performs internal tests on the EEPROM and can determine the integrity of the EEPROM's non-volatile memory. The ESC module compares the previously stored checksum with the checksum calculated when the ignition switch is first turned ON. If the two checksums do not match, the ESC module will indicate that a calibration malfunction (checksum error) is current.

Conditions for Setting the DTC
    • The stored checksum does not match the calculated checksum.
    • The ESC module detects an internal memory malfunction (checksum error).
    • The malfunction must be detected when the ignition switch is first turned to the ON position. The ignition switch must be OFF first for 10 seconds.

Action Taken When the DTC Sets
    • Stores a DTC C1658 in the ESC memory.
    • Depending on which internal circuitry was affected by this malfunction, the ESC module will command one of the following actions:
       - Command 0% PWM duty cycle in order to disable all four shock absorber solenoids.
       - Ignore the steering position input.
       - Provide shock absorber solenoid control based on the vehicle speed only.
       - Sends a message to the IPC to display the SERVICE RIDE CONTROL message.
       - Sends a message to the IPC to display the SHOCKS INOPERATIVE message.
    • If the disable all four shock absorber solenoids action was taken, the ESC module sends a message to the 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.

Conditions for Clearing the DTC
    • Under all fault conditions, the ignition must be cycled before this DTC can change from current to history.
    • The ESC module no longer detects an internal memory malfunction (checksum error) condition when the ignition is cycled from OFF to ON.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Use the IPC clearing DTC feature.
    • Using a scan tool.

Diagnostic Aids
    • Since DTC C1658 is an internal malfunction to the ESC module, there is no repair procedure, and the module must be replaced.
    • The ESC module tests for multiple internal malfunctions, and will store a DTC C1658 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 numbers below refer to the step numbers on the diagnostic table:

  1. This step checks if DTC C1658 will reset in the ESC module's memory. If DTC C1658 resets, the ESC module must be replaced.

Step

Action

Value(s)

Yes

No

1

Was the RTD Diagnostic System Check performed?

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Go to Step 2

Go to RTD Diagnostic System Check

2

  1. Using a scan tool, select clear DTCs.
  2. Cycle the ignition OFF then ON.
  3. Using a scan tool, check for DTCs.

Does DTC C1658 reset?

--

Go to Step 3

System OK

3

Replace the ESC module. Refer to Electronic Suspension Control Module Replacement .

Is the repair complete?

--

Go to Step 4

--

4
  1. Turn OFF the ignition switch.
  2. Connect or install any connectors or components that were disconnected or removed.
  3. Turn ON the ignition switch.
  4. Using the scan tool, select clear DTCs.

Is the repair complete?

--

Go to RTD Diagnostic System Check

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