Scan Tool Does Not Communicate with Component. Chevrolet Epica 2005

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 Epica 🢒 Engine 🢒 Engine Electrical 🢒 Scan Tool Does Not Communicate with Component

Circuit Description

The provisions for communicating with the engine control module (ECM), electronic brake control module (EBCM), SIR module, Immobilizer Module, and the Theft Deterrent module are located in the data link connector (DLC). The DLC is located under the instrument panel (IP). The 16 pin DLC provides the serial data signal at terminals 7 (ECM, TCM, ABS and ISU serial data), terminals 3 (2.5 L speed sensitive power steering), terminals 14 (2.0 L speed sensitive power steering), and terminals 13 (SIR serial data). The DLC is used to link a scan tool to the ECM, EBCM, SIR, intelligent switching unit (ISU), and speed sensitive steering module (SSPS) serial data stream. Some common uses of the scan tool are listed below:

•	Identifying the stored diagnostic trouble codes (DTC)

•	Reading the serial data stream

•	Clearing the DTCs

•	Storing the Freeze Frame data

Diagnostic Aids

Some scan tools may require an external power supply . Ensure the scan tool is correctly connected to the power feed.

Ensure that the correct application (module year, carline, VIN code) has been selected on the scan tool. If communications are still not established, try the scan tool on another vehicle in order to ensure that the scan tool or the connecting cables are not the cause of the malfunction. Always try the scan tool on a vehicle that uses the same DLC terminal for serial data communication.

Any circuitry that is suspect to an intermittent complaint should be thoroughly inspected for the following:

Backed-out terminals
Broken electrical connector locks
Improperly formed or damaged terminals
Faulty terminal-to-wiring connections
Physical damage to the wiring harness
A broken conductor inside the wire insulation
Corrosion of the electrical connections, the splices, or the terminals

Test Description

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

This step checks whether the scan tool can communicate with other control modules on the vehicle. If the scan tool can communicate with one of the other modules then the DLC connector, the shared Circuits, and the scan tool are OK.

This step checks whether the ECM is receiving ignition positive voltage from the fuse F16 when the ignition is ON. The ECM cannot provide serial data without ignition positive voltage.

This step checks for a high resistance or open/short in the ECM serial data circuit.

This step checks the ECM DLC Diagnostic circuit high resistance or open/short. This could cause the ECM not to communicate.

This step checks to see if the EBCM is not communicating with the scan tool.

This step checks to see if the SIR system is not communicating with the scan tool.

This step checks to see if the Theft Deterrent-Immobilizer system is not communicating with the scan tool.

Step	Action	Yes	No
Schematic Reference: Data Link Connector Schematics
1	Have you performed the Diagnostic System Check for the system in which the customer concern is apparent?	Go to Step 2	Go to Diagnostic System Check - Engine Controls in Engine Controls 2.0 L, or Diagnostic System Check - ABS in Antilock Brake System, or Diagnostic System Check - SIR in SIR, or Diagnostic Starting Point - Theft Deterrent in Theft Deterrent
2	Does the scan tool power up?	Go to Step 3	Go to Scan Tool Does Not Power Up
3	Does the scan tool communicate with the engine control module (ECM)?	Go to Step 9	Go to Step 4
4	With the ignition OFF: Disconnect the ECM connector. Turn ON the ignition. Test the ECM battery positive (B+) and/or ignition voltage circuits with a test lamp connected to ground. Does the test lamp illuminate for all circuits?	Go to Step 5	Go to Step 24
5	With the ECM still disconnected, test the ECM ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all ground circuits?	Go to Step 6	Go to Step 24
6	Reconnect the ECM connector. Connect the scan tool. Turn ON the ignition, with the engine OFF. Does the scan tool display serial data?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 7
7	Test the serial data circuit for an open, high resistance, or a short circuit. Refer to Circuit Testing in Wring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 8
8	Test the DLC Diagnostic circuit for an open, high resistance or a short circuit. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 25
9	Does the scan tool communicate with the EBCM?	Go to Step 14	Go to Step 10
10	Test the EBCM battery positive (B+) and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits?	Go to Step 11	Go to Step 24
11	Test the EBCM ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits?	Go to Step 12	Go to Step 24
12	Test the EBCM serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 13
13	Check the EBCM connectors. Refer to Wiring Repairs or Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 26
14	Does the scan tool communicate with the SIR Module?	Go to Step 19	Go to Step 15
15	Test the SIR Module battery positive (B+) and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits?	Go to Step 19	Go to Step 24
16	Test the SIR Module ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits?	Go to Step 17	Go to Step 24
17	Test the SIR serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 18
18	Check the SIR Module connectors. Refer to Wiring Repairs or Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 27
19	Does the scan tool communicate with the intelligent switching unit (ISU)?	Go to Step 29	Go to Step 20
20	Test the ISU battery positive (B+) and/or ignition voltage circuits with a test lamp to ground. Does the test lamp illuminate for all circuits?	Go to Step 21	Go to Step 24
21	Test the ISU ground circuits with a test lamp connected to B+. Does the test lamp illuminate for all circuits?	Go to Step 22	Go to Step 24
22	Test the ISU serial data circuit for an open, high resistance, or short circuit. Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 23
23	Check the ISU connectors. Refer to Wiring Repairs or Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 29	Go to Step 28
24	Repair the circuit as necessary. Refer to Wiring Repairs or Connector Repairs in Wiring Systems. Is the action complete?	Go to Step 29	--
25	Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls 2.0 L, or Engine Control Module Replacement in Engine Controls 2.5 L. Is the action complete?	Go to Step 29	--
26	Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement in Antilock Brake System. Is the action complete?	Go to Step 29	--
27	Replace the SIR Module. Refer top Inflatable Restraint Sensing and Diagnostic Module Replacement in SIR. Is the action complete?	Go to Step 29	--
28	Replace the ISU. Refer to Intelligent Switching Unit Replacement in Body Control Systems. Is the action complete?	Go to Step 29	--
29	Operate the system in order to verify the repair. Is the action complete?	System OK	Go to Step 3