Circuit Description
Modules connected to the controller area network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. If no communication is detected on
CAN serial data circuit, the DTC is set. A total non communication condition may be caused by one of the following conditions:
| • | A short to ground on any of the CAN circuits |
| • | A short to voltage on any of the CAN circuits |
| • | A short between the CAN high and low circuits |
The following modules communicate on CAN serial data circuits:
| • | The engine control module (ECM) |
| • | The transmission control module (TCM) |
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P1672 Controller Area Network (CAN) Bus Communication
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | DTC P1672 runs continuously once the above condition is met for more than 10 seconds. |
Conditions for Setting the DTC
A total non communication condition is detected on CAN serial data circuit.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp
(MIL) on the second consecutive ignition cycle that the diagnostic runs and
fails. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The first time the diagnostic fails, the control module
stores this information in the Failure Records. If the diagnostic reports
a failure on the second consecutive ignition cycle, the control module
records the operating conditions at the time of the failure. The control
module writes the operating conditions to the Freeze Frame and updates
the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL)
after 3 consecutive ignition cycles that the diagnostic runs and does
not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs
and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles,
if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
