For 1990-2009 cars only
Circuit Description
DTC 55 is an internal control unit hardware failure (RAM, ROM defective) in the heater and A/C control.
Conditions for Setting the DTC
| • | The heater and A/C control detects an internal hardware malfunction. |
| • | The heater and A/C control checks the hardware on a continuous basis every 200 ms. |
Action Taken When the DTC Sets
| • | Stores a DTC 55 in the controllers memory. |
| • | Disables all heater and A/C control functions. |
Conditions for Clearing the DTC
| • | The condition for the fault is no longer present. |
| • | The use of a scan tool. |
| • | A history DTC will clear after 20 consecutive ignition cycles if the condition for the fault is no longer present. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the HVAC Systems Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
Replace the heater and A/C control module. Did you complete the replacement? | -- | System OK | -- |
