C0870

DTC C0870





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, air pressure sensor and the steering handwheel position/speed 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 EVO outputs.
^ 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 BIDE 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 theta 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.
^ A short to voltage in the 5 volt reference of the steering handwheel position/speed sensor.
^ A short to ground in the 5 volt reference of the steering handwheel position/speed 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. Tests all suspension position sensors reference voltage circuits.
4. Tests the 5 volt reference circuit of the steering handwheel position/speed sensor for a short to ground and a short to voltage.
5. Tests the 5 volt reference circuit of the air pressure sensor for a short to ground and a short to voltage.
7. Clear DTCs and checks to see if DTC will reset.