Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC U1866 00: Battery Energy Control Module Lost Communication With Body Control ModuleDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
BCM B+ | U1866*, U0140 in EBCM | U1866*, U0140 in EBCM | -- | -- |
BCM Ground | -- | U1866*, U0140 in EBCM | -- | -- |
HSGMLAN + (circuit 2500) | 1* | U1866*, U0140 in EBCM | 1* | -- |
HSGMLAN - (circuit 2501) | 1* | U1866*, U0140 in EBCM | 1* | -- |
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device. | ||||
Circuit/System Description
Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.
Conditions for Running the DTC
| • | The system voltage is between 9-16 volts. |
| • | The vehicle power mode master requires serial data communication to occur fro this specific module. |
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTC Sets
The modules is never signaled, therefore the specific subsystems will not function.
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 of 50, without a repeat of the malfunction. |
Circuit/System Verification
Verify that DTC U0140 is not set in the electronic brake control module (EBCM).
| ⇒ | If DTC U0140 is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
