C0870

DTC C0870
Circuit Description
The Electronic Suspension Control (ESC) module provides a common regulated voltage of approximately 5 volts to all 4 of the body-to-wheel suspension position sensors and the air pressure sensor. The ESC module monitors this reference voltage for any malfunctions that could prevent it from outputting a regulated 5 volts.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0870 Device Voltage Reference Output (Signal or 1) Circuit

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 volts or greater than 6 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 4 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.
3. This step tests all suspension position sensor reference voltage circuits.
4. This step tests the 5-volt reference circuit of the air pressure sensor for a short to ground and a short to voltage.
6. Clear DTCs and check to see if the DTC will reset.