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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 DTC 🢒 DTC U1016 Loss of PCM Class 2 Serial Data Com

Object Number: 385137 Size: MF

Circuit Description

The BCM receives a state of health message from the Powertrain Control Module (PCM) through the Class 2 serial data link.

Conditions for Setting the DTC

The BCM does not receive a state of health message from the PCM after receiving other messages from the PCM.

Action Taken When the DTC Sets
    • The BCM stores DTC U1016 in memory.
    • The SERVICE VEHICLE SOON indicator lamp turns on.

Conditions for Clearing the DTC
    • DTC U1016 changes the status from current to history when the BCM detects a state of health message from the PCM.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
    • Using a scan tool.

Diagnostic Aids
    • The following conditions may cause an intermittent malfunction to occur:
      • An intermittent open, short to ground, or short to B+ in circuit 1037 or 1049.
      • Poor connections at the BCM or the PCM.
    • The Body Control Module (BCM) may store DTC U1016 if certain diagnostics are performed between the Powertrain Control Module (PCM) and the Data Link Connector (DLC).
    • DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is on with the Body Control Module (BCM) disconnected. When BCM diagnostics and repairs are completed, refer to Engine Controls for additional information on PCM related DTCs.

Test Description

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

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

    2.

  2. This step checks for a short to ground in circuit 1049.

    3.

  3. This step checks for a short to B+ in circuit 1049.

    4.

  4. This step checks for an open in circuit 1049.

    5.

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

Step

Action

Value(s)

Yes

No

1

Was the BCM diagnostic system check performed?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the scan tool from the DLC.
  3. Disconnect battery negative terminal.
  4. Using a DMM, measure the resistance between the SP205 terminal A and each of the SP205 terminals B, E, G, M and the SIR terminal one terminal at a time.

Is the resistance measured within the specified range?

Less than 2 ohms

Go to Step 3

Go to Step 7

3

  1. Disconnect the Powertrain Control Module (PCM) connector C1.
  2. Using a DMM, measure the resistance between the SP205 harness connector terminal B and ground.

Is the resistance measured same as the specified value?

∞

Go to Step 4

Go to Step 8

4

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

Is the voltage measured within the specified range?

Less than 2 V

Go to Step 5

Go to Step 9

5

  1. Turn the ignition switch to the OFF position.
  2. Using a DMM, measure the resistance between the SP205 harness connector terminal B and the PCM harness connector C1 terminal 58.

Is the resistance measured within the specified range?

Less than 5 ohms

Go to Step 6

Go to Step 10

6

  1. Reconnect the PCM connector C1.
  2. Turn the ignition switch to the ON position.
  3. Using a scan tool, communicate with the PCM.

Does the scan tool communicate with PCM?

--

Go to Step 11

Go to Powertrain Control Module Diagnosis in Engine Controls

7

Replace the Splice Pack SP205.

Is the repair complete?

--

Go to Step 11

--

8

Repair short to ground in circuit 1049.

Is the repair complete?

--

Go to Step 11

--

9

Repair short to B+ in circuit 1049.

Is the repair complete?

--

Go to Step 11

--

10

Repair poor connection or open in circuit 1049.

Is the repair complete?

--

Go to Step 11

--

11
  1. Turn the ignition switch to the OFF position.
  2. Reinstall connectors/components removed.
  3. Turn the ignition switch to the ON position.
  4. Clear BCM DTCs. Refer to Clearing DTCs for more information.
  5. Check for BCM current DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information.

Are there any BCM current DTCs set?

--

Go to Diagnostic System Check - Body Control System

System OK