GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Regal 🢒 DTC 🢒 DTC U1016 Loss of PCM Class 2 Serial Data Com

Object Number: 338989 Size: MF

Circuit Description

The BCM receives a state of health message from the powertrain control module (PCM) through the Class II serial data link.

Conditions for Running the DTC

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

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.

Conditions for Clearing the MIL/DTC
    • The DTC U1016 changes 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 malfunction is no longer present.
    • Use 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 CKT 1037 or CKT 1049.
       - Poor connections at the BCM or the PCM.
       - An intermittent open in the splice pack SP205.
    • The Body Control Module (BCM) may store DTC U1016 if certain diagnostics are performed between the powertrain control module (PCM) and the Date Link Connector.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step inspects for an open in the SP205.

    2.

  2. This step inspects for a short to ground in CKT 1049.

    3.

  3. This step inspects for a short to B+ in CKT 1049.

    4.

  4. This step inspect for an open in CKT 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 On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the scan tool from the DLC.
  3. Disconnect SP205.
  4. Use a digital multimeter (DMM) in order to measure the resistance between the SP205 terminal A and each of the SP205 terminals B, E, G, L an M, one at a time.

Is the resistance less than the specified value?

2ohms

Go to Step 3

Go to Step 7

3

  1. Disconnect the powertrain control module (PCM) connector C1.
  2. Use a DMM in order to measure the resistance between the SP205 harness connector terminal B and ground.

Is the resistance within the specified range?

∞

Go to Step 4

Go to Step 8

4

  1. Turn the ignition switch to the RUN position.
  2. Use a DMM in order to measure the voltage between the SP205 harness connector terminal B and ground.

Is the voltage less than specified range?

2V

Go to Step 5

Go to Step 9

5

Use a DMM in order to measure the resistance between the SP205 harness connector terminal B and ground.

Is the resistance same as the specified value?

∞

Go to Step 6

Go to Step 10

6
  1. Turn the ignition switch to the LOCK position.
  2. Reconnect the PCM connector C1.
  3. Turn the ignition switch to the RUN position.
  4. Use a scan tool in order to attempt to communicate with the PCM.

Does the scan tool communicate with the PCM?

--

Go to Step 11

Refer to Engine Controls.

7

Replace the SP205.

Is the repair complete?

--

Go to Step 11

--

8

Repair the short to ground in CKT 1049.

Is the repair complete?

--

Go to Step 11

--

9

Repair the short to B+ in CKT 1049.

Is the repair complete?

--

Go to Step 11

--

10

Repair the poor connection or the open in CKT 1049.

Is the repair complete?

--

Go to Step 11

--

11

  1. Turn the ignition switch to the LOCK position.
  2. Reinstall the connectors/components removed.
  3. Turn the ignition switch to the RUN position.
  4. Use the Tech 2 scan tool in order to clear the BCM DTCs.
  5. Use the Tech 2 scan tool in order to inspect for the BCM current DTCs.

Are there any BCM current DTCs set?

--

Refer to Diagnostic System Check - Body Control System

System OK