Diagnostic Instructions
DTC Descriptors
DTC C126C: Control Module Communication Bus B Off
DTC C126D: Control Module Communication Bus B Off
DTC C12E3: Control Module Communication Bus B Off
DTC U180F: Control Module Communication Bus B Off
Circuit/System Description
The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system
is inoperative the modules will still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial
data system.
Conditions for Running the DTCs
| • | Supply voltage to the modules are in the normal operating range. |
| • | The ignition switch in any position other than START. |
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.
Action Taken When the DTCs Sets
| • | The module suspends all message transmission. |
| • | The MIL and battery indicators will illuminate, along with several DIC messages. |
| • | The vehicle may continue to run for several minutes, then will stall and not start. |
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Reference Information
Schematic Reference
Connector End View Reference
Component Connector End Views
Description and Operation
Data Link Communications Description and Operation
Electrical Information Reference
Circuit/System Testing
Verify that DTC U0074 is not set.
