GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Regal 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC U1064 Loss of Communications with DIM

Object Number: 308553 Size: SF
Instrument Cluster Components
Instrument Cluster: Analog Schematics
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The instrument cluster receives a state of health message from modules whose source IDs it has learned. If the instrument cluster does not see a state of health message from the Body Control Module (BCM), this DTC will set.

Conditions for Setting the DTC

The instrument cluster does not receive a state of health message from the Body Control Module (BCM).

Action Taken When the DTC Sets
    • The instrument cluster stores DTC U1064 in memory.
    • The SERVICE VEHICLE SOON indicator turns on.

Conditions for Clearing the DTC
    • Under all fault conditions the ignition switch must be cycled from on to off, back to on before this DTC can change from current to history.
    • The instrument cluster detects a state of health message from the BCM.
    • A history DTC will clear after 100 drive cycles if the condition for this DTC is no longer present.
    • Use a scan tool.

Diagnostic Aids

The following conditions may cause an intermittent malfunction to occur:

   • 

An intermittent open in circuit 1037.

   • 

Poor connections at the instrument cluster or the BCM.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for an internal open in the Splice Pack SP205.

    2.

  2. This step tests for a short to ground in circuit 1037.

    3.

  3. This step tests for a short to B+ in circuit 1037.

    4.

  4. This step tests for an open in circuit 1037.

    5.

  5. This step determines whether the malfunction is intermittent or the BCM is faulty.

Step

Action

Value(s)

Yes

No

1

Was the instrument cluster diagnostic system check performed?

--

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console

2

  1. Turn the ignition switch off.

    2. Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  2. Disconnect the battery negative terminal.
  3. Disconnect the scan tool from the DLC.
  4. Using a DMM, backprobe to measure the resistance between the SP205 terminal A and each of the SP205 terminals B, E, G, L, and M; one terminal at a time.

Is the resistance less than the specified value?

2ohms

Go to Step 3

Go to Step 7

3

  1. Disconnect the Body Control Module (BCM) harness connector C2.
  2. Using a DMM, in measure the resistance between the SP205 harness connector terminal M and ground.

Is the resistance within the specified range?

∞

Go to Step 4

Go to Step 8

4

  1. Reconnect the negative battery terminal.
  2. Turn the ignition switch on.
  3. Using a DMM, measure the voltage between the SP205 harness connector terminal M and ground.

Is the voltage less than the specified value?

2 V

Go to Step 5

Go to Step 9

5

  1. Turn the ignition switch off.
  2. Using a DMM, measure the resistance between the SP205 harness connector terminal M and the BCM harness connector C2 terminal B5.

Is the resistance less than the specified value?

2ohms

Go to Step 6

Go to Step 10

6
  1. Turn the ignition switch off.
  2. Reconnect the BCM.
  3. Turn the ignition switch on.
  4. Using a scan tool, attempt to communicate with the BCM.

Does the scan tool communicate with the BCM?

--

Go to Step 11

Go to Diagnostic System Check - Body Control System

7

Replace the SP205.

Is the repair complete?

--

Go to Step 11

--

8

Repair short to ground in circuit 1037.

Is the repair complete?

--

Go to Step 11

--

9

Repair short to B+ in circuit 1037.

Is the repair complete?

--

Go to Step 11

--

10

Repair poor connection or open in circuit 1037.

Is the repair complete?

--

Go to Step 11

--

11

  1. Turn the ignition switch off.
  2. Reconnect or install any connectors or components that were disconnected or removed.
  3. Clear DTCs in the instrument cluster. Refer to Clearing DTCs in Instrument Panel, Gauges and Console for more information.
  4. Test for DTCs in the instrument cluster. Refer to Diagnostic Trouble Code (DTC) Displaying in Instrument Panel, Gauges and Console for more information.

Are any DTCs stored in the instrument cluster?

--

Go to Diagnostic System Check - Instrument Cluster

System OK