GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 S10 - Electric 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Scan Tool Does Not Communicate with Class 2 Data Line

Step

Action

Value(s)

Yes

No

Tools Required

    • Scan Tool
    • J 39200 Digital Multimeter (DMM)
    • J 35616 Connector Test Adapter Kit

1

Did you perform the Data Link Communications System check?

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Go to Step 2

Go to Diagnostic System Check - Data Link Communications

2
  1. Connect a scan tool
  2. Turn the ignition switch to the RUN position.
  3. Use the scan tool to attempt to establish communication with each module on the Class 2 data link. If using a Tech 2, the Class 2 Message Monitor feature can be used to obtain this information.

Are there any modules on the Class 2 data link which are communicating?

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Go to Step 3

Go to Step 4

3

Is DTC U1000 or DTC U1XXX (Lost Communications With XXX) set in the modules which will communicate?

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Go to Diagnostic System Check - Data Link Communications

Go to Step 18

4

    2. Turn ignition OFF.

  2. Test continuity of terminal 5 of DLC to ground. Refer to Testing for Continuity in Wiring Systems.

Is the resistance within the specified value?

0-5 ohms

Go to Step 6

Go to Step 5

5

Repair open ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

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6
  1. Disconnect SP201.
  2. Measure the resistance from terminal 2 of the DLC to terminal A of SP201. Refer to Testing for Continuity in Wiring Systems.

Is the resistance within the specified value?

0-5 ohms

Go to Step 8

Go to Step 7

7

Repair open in Class 2 data circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

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8

Test terminal 2 of the DLC for short to ground. Refer to Testing for Short to Ground in Wiring Systems.

Did you find and repair a short to ground?

--

Go to Step 17

Go to Step 9

9
  1. Turn Ignition switch to RUN
  2. Test voltage on DLC cavity 2. Refer to Measuring Voltage in Wiring Systems.

Is voltage within specified value?

0-1 V

Go to Step 11

Go to Step 10

10
  1. Turn ignition switch to OFF.
  2. Repair short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

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11
  1. Turn the ignition switch OFF.
  2. Connect a jumper wire to terminal A of splice pack SP201.
  3. Connect the other end of the jumper wire to a terminal in splice pack SP201 that is connected with a module.
  4. Turn the ignition switch to the RUN position.
  5. Use the scan tool to attempt to establish communication with the module which is jumpered to the DLC.

Can communication be established?

--

Go to Step 12

Go to Step 13

12

Repeat step 11 for each module on the Class 2 serial data link.

Can communication be established for each module on the Class 2 serial data link?

--

Go to Step 17

Go to Step 13

13
  1. Turn ignition switch OFF.
  2. Disconnect the module which does not communicate.
  3. Test disconnected module Class 2 serial data circuit for short to ground. Refer to Testing for Short to Ground in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 14

14
  1. Turn the ignition switch to the RUN position.
  2. Measure the voltage of the disconnected module Class 2 serial data circuit. Refer to Measuring Voltage in Wiring Systems.

Is the voltage within the specified range?

0-1 V

Go to Step 16

Go to Step 15

15
  1. Turn the ignition switch OFF.
  2. Repair the short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

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16
  1. Turn ignition switch OFF.
  2. Check connections at the module. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  3. Replace the module that does not communicate. Refer to the appropriate on-vehicle service procedures for the module being replaced to ensure a complete repair.

Did you complete the repair?

--

Go to Step 17

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17
  1. Reconnect splice pack SP201.
  2. Reconnect all the modules on the Class 2 serial data link.
  3. Turn ignition switch to RUN.
  4. Wait for 10 seconds.
  5. Inspect for DTCs in each module on the Class 2 serial data link.

Are there any DTCs that begin with a U set?

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Go to Step 19

Go to Step 18

18

Are there any DTCs that do not begin with a U set?

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Go to Step 19

Go to Step 20

19

Diagnose the DTCs as directed by the diagnostic procedures for the particular module or malfunction.

Is the procedure complete?

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Go to Step 20

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20

Clear all the DTCs.

Is the procedure complete?

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Go to Diagnostic System Check - Data Link Communications

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