GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Tahoe - 4WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC U1885

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 U1885 00: Battery Energy Control Module Lost Communication With Hybrid Powertrain Control Module

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

HSGMLAN + (circuit 2500)

U0073*

U1885*

U0073*

--

HSGMLAN - (circuit 2501)

U0073*

U1885*

U0073*

--

* Other modules/DTCs will set with this fault.

Circuit/System Description

Modules connected to the 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.

DTC U1885 will set in the hybrid powertrain control module (HPCM) when the drive motor generator battery control module (BECM) looses communication with the serial data gateway module (SDGM) on the HSGMLAN serial data bus . The BECM communicates only on the PTLAN serial data bus while the HPCM communicates on the PTLAN and the HSGMLAN serial data bus.

Conditions for Running the DTC
    • The system voltage is between 9-16 volts.
    • The vehicle power mode master requires serial data communication to occur from 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.

Diagnostic Aids
    • When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to Instrument Panel Center Trim Panel Replacement .
    • Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Circuit/System Verification

Verify the following DTCs are not set in the modules as follows:

  1. Verify DTC U0111 is not set in the SDGM.
    2. ⇒If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Verify DTC U1888 is not set in the HPCM.
    3. ⇒If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .