U0293

DTC U0293

CIRCUIT DESCRIPTION
Modules connected to the high 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. 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. When a message that indicates the availability of the transmitter module is not received, the receiver module sets a DTC.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC U0111 Lost Communication With Energy Storage Control Module (ESCM)
- DTC U0120 Lost Communication With Starter/Generator Control Module (SGCM)
- DTC U0131 Lost Communication With Electro-Hydraulic Power Steering (EHPS) Module
- DTC U0293 Lost Communication With Hybrid Control Module (HCM)

CONDITIONS FOR RUNNING THE DTCS
Voltage supplied to the modules is in the normal operating voltage range.

CONDITIONS FOR SETTING THE DTC
A supervised periodic message that includes the transmitter module availability has not been received by the powertrain control module (PCM) from any of the high speed GMLAN modules.

ACTION TAKEN WHEN THE DTC SETS
The module uses a default value for the missing parameter.

CONDITIONS FOR CLEARING THE MIL/DTC
- The malfunction indicator lamp (MIL) clears after 3 ignition cycles when the malfunction is no longer present.
- 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.

DIAGNOSTIC AIDS
The following conditions may cause the DTC to set:
- A poor connection at the inoperative module
- An intermittent open on high speed GMLAN
- An open voltage or ground circuit to a module
- An internal module malfunction

TEST DESCRIPTION

Step 1:

Step 2:

Steps 3 - 6:

Step 7:

Steps 8 - 9:

Step 10:

Steps 11 - 14:

The number below refers to the step number on the diagnostic table.
12. The module which was not communicating may have set Loss of Communication DTCs for those modules that it was monitoring.