For 1990-2009 cars only
Schematic Reference HVAC Air Delivery/Temperature Control Schematics
Circuit Description
The HVAC (ECC) module communicates with the Body Control Module (BCM) via the data bus. This communication link is used by all modules on the Class II data link.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
| • | There is a checksum (EEPROM) and (ROM) error within the HVAC (ECC) controller. |
| • | The above conditions are present for 30 seconds. |
Action Taken When the DTC Sets
| • | The automatic portion of the heater and A/C system will be disabled. |
| • | Upon any ignition signal to the HVAC (ECC) module, the ECC shall compute a checksum value for EEPROM and a check sum value for ROM and compare them to their respective checksum reference values stored in the ECC controller. If either calculated chedksum value is not equal to its respective checksum reference value, the DTC shall set to a current code. |
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC Module no longer detects a failure. |
| • | The history DTC will clear after 50 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 |
Does the scan tool display DTC B1000? | -- | Go to Step 3 | Go to Diagnostic System Check |
3 |
Important: When ever the HVAC (ECC) module is replaced, the reconfiguring process must be followed in the repair procedure. Replace the HVAC (ECC ) control module. Refer to Control Assembly Replacement . Is the repair complete? | -- | System OK | -- |
