DTC U0100-U0299. Pontiac GTO 2006

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2006 🢒 GTO 🢒 DTC 🢒 DTC U0100-U0299

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, 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. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•	DTC U0101 Lost Communication With Transmission Control Module (TCM)

•	DTC U0121 Lost Communication With Electronic Brake Control Module (EBCM)

Conditions for Running the DTCs

•	Voltage supplied to the modules is in the normal operating voltage range.

•	The vehicle power mode requires serial data communication to occur.

•	The DTC U0001 does not have a current status.

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 module uses a default value for the missing parameter.

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.

Diagnostic Aids

•	A poor connection at the inoperative module may cause this code to set.

•	An improperly powered module may cause this code to set.

Step

Action

Yes

Schematic Reference: Data Link Connector Schematics

Connector End View Reference: Computer/Integrating Systems Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Attempt to communicate with the electronic brake control module (EBCM) and the transmission control module (TCM).

Were you able to communicate with EBCM and TCM?

Go to Step 6

Go to Step 3

Turn OFF the ignition.
Test all the high speed GMLAN serial data circuits between the EBCM, the TCM, and the Engine Control Module (ECM) for an open.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

Important: Use the DTC list from DTC Descriptors to determine the closest module to DLC which is not communicating.

Test the following circuits of the module that is not communicating, for an open or a short to ground:

•	The battery positive circuits

•	The battery voltage output circuits

•	The switched battery positive voltage circuits

Did you find and correct the condition?

Go to Step 6

Go to Step 5

Replace the module that is not communicating. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 6

Retrieve DTCs from the modules which had the Loss of Communications DTC set.

Does the scan tool display any DTCs which do not begin with a "U"?

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Go to Step 7

Use the scan tool in order to clear the DTCs.
Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared.

Did you complete the action?

System OK