Circuit Description
The serial data line allows all the modules on the line to transmit information to each other as needed.
Each module is assigned an ID and all the information sent out on the line is assigned a priority by which the data is received. When the ignition switch is turned to the ON position, each module begins to send and receive information.
Each module on the serial data line knows what information to send out and what information to expect.
The module does NOT know who is sending this information until the ID of the sending module is received with the information.
This information is then remembered until the ignition switch is turned OFF. If a module never receives the information or the ID of the PCM, DTC U1016 will be set.
Conditions for Setting the DTC
The ignition is turned to the ON position, and the EBCM or the BCM does not receive the PCM message for 5 seconds.
Action Taken When the DTC Sets
A malfunction DTC is stored in the BCM, EBCM, and the PCM.
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists and the scan tool CLEAR DTCs function is used. |
| • | The EBCM clears when 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF. |
| • | The BCM history codes clear when 100 ignition cycles pass with no DTCs detected. |
Diagnostic Aids
| • | Perform a thorough inspection of the wiring and connectors. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing unnecessary part replacement with reappearance of the malfunction. |
| • | An intermittent malfunction is most likely caused by a poor connection, rubbed-through wire insulation, or a wire that is broken inside the insulation. |
Possible Causes
| - | Serial Data transmit malfunction on the PCM |
| - | Serial Data receiver malfunction on the EBCM or BCM |
| - | Open serial data line |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the diagnostic system check performed? | -- | Go to Step 2 | |
2 | Using a scan tool, read the BCM DTC(s). Is DTC U1016 also set as a current BCM DTC? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 2.4L or Powertrain On Board Diagnostic (OBD) System Check Engine Controls 3.1L | Go to Step 3 |
3 | Is DTC U1016 set as a current ABS DTC? | -- | Go to Step 4 | Go to Diagnostic System Check in Antilock Brake System |
4 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Is the replacement complete? | -- | Go to Diagnostic System Check in Antilock Brake System | -- |
