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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 U0100 Lost Communication With Engine Control Module (ECM)
DTC U0101 Lost Communication With Transmission Control Module (TCM)
DTC U0104 Lost Communication With Distance Sensing and Cruise Control (DSCC) Module
DTC U0121 Lost Communication With Electronic Brake Control Module (EBCM)
DTC U0141 Lost Communication With Instrument Panel Module (IPM)
DTC U0181 Lost Communication With Dynamic Headlamp Leveling (DHL) Control Module
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
DTC Symptom
DTC Symptom Descriptor
00
No Additional Information
Conditions for Running the DTC
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
No
Schematic Reference: Data Link Connector (DLC) Schematics
Connector End View Reference: Master Electrical Component List in Wiring Systems
1
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
Did you record any DTC in the range of U2105-U2199?
Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information
Go to Step 3
3
Important
Use the DTC list in DTC Descriptors to determine which module 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 voltage input circuits
The battery positive voltage output circuits
The ignition voltage input circuits
The ignition voltage output circuits
The switched battery positive voltage circuits
Refer to the following:
Control Module References for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 8
Go to Step 4
4
Turn OFF the ignition.
Test the ground circuits of the module that is not communicating for an open. If the module is the body control module (BCM), test its class 2 serial data circuit for an open, also.
Refer to the following:
Control Module References for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 8
Go to Step 5
5
Test the high speed GMLAN serial data circuits of the module that is not communicating for an open. Refer to Circuit Testing and GMLAN Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 8
Go to Step 6
6
Inspect the harness connectors of the module that is not communicating for poor connections and terminal tension at the following circuits:
The battery positive voltage input circuits
The battery positive voltage output circuits
The ignition voltage input circuits
The ignition voltage output circuits
The switched battery positive voltage supply circuits
The ground circuits
The high speed GMLAN serial data circuits
Refer to the following:
Control Module References for the applicable schematic
Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Connector Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 8
Go to Step 7
7
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 8
--
8
Use the scan tool in order to clear the DTCs.
Does the scan tool still display other current DTCs?
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
:blink:
太不环保了，所以，车子环保系统警告你，给你来了这么一下
