Circuit Description
The electronic suspension control (ESC) module provides a common regulated voltage of approximately 5 volts to all four of the body-to-wheel suspension position sensors and air pressure sensor. The ESC module monitors this reference voltage for any malfunctions that could prevent it from outputting a regulated 5 volts.
Conditions for Running the DTC
Continuously with the ignition on.
Conditions for Setting the DTC
The ESC module senses a sensor reference voltage of less than 4.0 volts or greater than 6.0 volts.
Action Taken When the DTC Sets
| • | Disable all compressor leveling functions, and assume default pressure. |
| • | Disable all suspension damper solenoid outputs. |
| • | The SERVICE RIDE CONTROL message will be displayed. |
| • | Stores a DTC C0870 in the ESC module memory. |
Conditions for Clearing the DTC
| • | The ESC module senses the correct voltage output to the suspension position sensors upon the next ignition cycle. |
| • | 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: Ignition cycle counting is used by the ESC module to detect faults in the system. The objective is to eliminate false/intermittent codes while maintaining an acceptable level of system performance. The operation of the ignition cycle counting requires that a fault condition be present for four consecutive ignition cycles before it will set the fault code and display the "SERVICE RIDE CONTROL" message. If a fault code is present (without a fault being current), the system will go into one or more degraded modes without displaying a message. Resetting the ignition cycle counter is done by clearing codes with a scan tool. Clearing codes will override ignition cycle counting for one ignition cycle. Therefore, a fault condition will set the fault code immediately if it occurs on the first ignition cycle after the codes are cleared.
| • | The following conditions may cause a malfunction to occur: |
| - | A short to voltage in any one of the body-to-wheel suspension position sensor reference voltage circuit |
| - | A short to ground in any one of the body-to-wheel suspension position sensor reference voltage circuit |
| • | If the circuit is shorted to ground, the scan tool will display all suspension position sensor voltage as zero. |
| • | If the circuit is shorted to an unwanted voltage source, the scan tool may display all suspension position sensor voltage as that voltage. |
| • | A short to voltage in the 5 volt reference of the air pressure sensor |
| • | A short to ground in the 5 volt reference of the air pressure sensor |
| • | An intermittent malfunction or DTC may cause a random firm/soft ride condition. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests all suspension position sensors reference voltage circuits.
-
Tests the 5 volt reference circuit of the air pressure sensor for a short to ground and a short to voltage.
-
Clear DTCs and checks to see if DTC will reset.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Suspension Controls Schematics and Automatic Level Control Schematics | |||
1 | Did you perform the ESC Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Electronic Suspension Control |
2 |
Does the scan tool indicate that all the above mentioned data parameters are less than 4 volts or greater than 6 volts? | Go to Step 3 | Go to Diagnostic Aids |
Test all 4 body-to-wheel suspension position sensor 5 volt reference circuits for a short to ground and a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 4 | |
Test the air pressure sensor 5 volt reference circuit for a short to ground and a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 | |
5 | Replace the ESC module. Refer to Electronic Suspension Control Module Replacement . Did you complete the replacement? | Go to Step 6 | -- |
Does the DTC reset? | Go to Step 2 | System OK | |
