U1064 - Loss of Communications with DIM (Dash Integration Module)
Here is some TSB
Refer to Data Link Connector (DLC) Schematics
Circuit Description
The class 2 serial data line communicates information between modules.
Each module connected to the serial data line is assigned a recognition
code, or address. This code is used in order to identify which modules
are communicating. Modules communicate with each other by periodically
sending state of health (SOH) messages. When the ignition switch is in
RUN, each module communicating on the serial data line sends a SOH
message every 2 seconds. This ensures that the system is operating
properly. When the dash integration module (DIM) stops communicating on
the class 2 serial data line, the SOH that is normally sent on the
serial data line every 2 seconds disappears. The module, which expects
to receive that message, detects the absence of the message. The module
in turn sets DTC U1064 associated with the loss of SOH of the DIM.
Conditions for Setting the DTC
The module does not receive a state of health (SOH) message back from
the DIM. The module retries the request 3 times, and then sets DTC
U1064.
This DTC only sets if U1300 or U1301 is not current.
Action Taken When the DTC Sets
DTC U1064 is stored in the module.
The module uses the default values for the initialization data. This DTC does not cause driver warning message to appear.
Conditions for Clearing the DTC
This DTC clears (status changes from current to history) under any of the following conditions:
The module detects a state of health message from the DIM.
At each ignition cycle.
A history DTC clears after 50 consecutive ignition cycles if the conditions for setting the DTC are no longer present.
Current and history DTCs may be cleared using a scan tool.
Diagnostic Aids
DTC U1064 does not normally represent a failure within the module.
When loss of class 2 serial data communication DTCs (DTCs with the
letter U as the prefix) are stored as history DTCs, know all possible
serial data DTCs set in each module before diagnosing the serial data
line.
If U1064 is stored in the module memory, inspect for the same DTC stored in other modules capable of storing this DTC.
If the DTC is a history DTC, the problem may be intermittent.
Test Description: The numbers below refer to the step numbers on the diagnostic table:
U1064 is the result of loss of communication with the dash integration
module (DIM). Note that other modules on the class 2 serial data line
may also set U1064 if the DIM is not communicating with the serial data
line.
Clear all DTCs after the repair procedure is complete.
Step
Action
Value(s)
Yes
No
1
Did you perform the Data Link Communications Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - Data Link Communications
2
Use a scan tool in order to attempt the establish communication with the dash integration module (DIM).
Does the scan tool communicate with the DIM?
--
Go to Step 3
Go to Diagnostic System Check - Body Control System in Body Control System.
3
Inspect and repair the class 2 serial data line CKT 1807 (PPL) for
intermittent connections. Refer to Intermittents and Poor Connections
Diagnosis in Wiring Systems.
Is the repair complete?
--
Go to Step 4
--
4
Turn off the ignition switch.
Reconnect or install any connectors or components that were disconnected or removed.
Turn on the ignition switch.
Clear any DTCs.
Is the repair complete?
U1096 - Loss of Communications with IPC
The computers on the Chevy require a certain voltage to operate and if the
voltage drops below a preset limit then it will tripper a loss of
communication with the other modules, this drop in voltage happens when
the car is started and the draw on the starter uses a large amount of
amperage. I suggest to check power/ground in the instrument cluster and if good do a resistance test on Data wire.
If your car is not experincing any messages like "service vehicle soon"
and no warning lights are illuminating then disregard these codes.
Hope helps.
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