Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.
The engine will not start when there is a total loss of class 2 serial data communication while the ignition is OFF. The following conditions will cause a total loss of class 2 serial data communication:
• | A class 2 serial data circuit shorted to ground. |
• | A class 2 serial data circuit shorted to voltage. |
• | An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial data circuit. |
The numbers below refer to the step numbers on the diagnostic table.
A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit. The following modules communicate on the class 2 serial data circuit:
• | Air Suspension Module (ESC) |
• | Audio Amplifier |
• | BCM |
• | DDM |
• | EBCM |
• | FPDM |
• | HVAC Control Module |
• | IPC |
• | MSM-Driver |
• | PCM |
• | Radio |
• | RSA Module |
• | SDM |
• | TCSCM |
• | VCIM |
The following DTCs may be retrieved with a history status, but are not the cause of the present condition.
• | U1300 |
• | U1301 |
• | U1305 |
A state of health DTC with a history status may be present along with a U1000 or U1255 code having a current status. This indicates that the malfunction occurred when the ignition was ON.
Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
A poor connection at DLC terminal of the splice pack - SP205 would cause this condition but will not set a DTC.
An open in the class 2 serial data circuit between the DLC and splice pack - SP205 will prevent the scan tool from communicating with any module. This condition will not set a DTC.
The class 2 serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the BCM and the PCM class 2 serial data circuits.
This test isolates the BCM class 2 serial data circuits.
The BCM detects that the ignition is ON and sends the appropriate power mode message to the other modules. Therefore, the BCM must remain connected to the DLC for any other module to communicate with the scan tool. This test isolates the splice pack - SP207 serial data circuits.
This test isolates the splice pack - SP206 serial data circuits and radio.
This test isolates the EBCM and TCSCM class 2 serial data circuits.
This test isolates the rest of the splice pack - SP205 serial data circuits.
If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
The communication malfunction may have prevented diagnosis of the customer complaint.
Step | Action | Yes | No | ||
---|---|---|---|---|---|
Schematic Reference: Data Link Connector Schematics Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views in Wiring Systems | |||||
1 | Does the scan tool power up? | Go to Step 2 | |||
Does the scan tool communicate with any module on the class 2 serial data circuit? | Go to Step 3 | Go to Step 8 | |||
Did you record any DTCs in the range of U1000 to U1305? | Go to Step 4 | Go to Step 7 | |||
4 | Are the history DTCs U1300, U1301 or U1305 retrieved from any module? | Go to Step 5 | Go to Step 6 | ||
5 |
Important:: Turn ON the ignition, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions. Test the class 2 serial data circuit for an intermittent short to ground or an intermittent short to voltage. Refer to the following:
Did you find and correct the condition? | Go to Step 36 | Go to Step 6 | ||
Is U1000 or U1255 the only DTC displayed in the previously specified range? | Go to DTC U1000 and U1255 | Go to DTC U1001-U1254 | |||
Diagnose the non-communicating module by using the DTC U1001-U1254 procedure for the module which is not communicating. Refer to DTC U1001-U1254 Did you complete the action? | Go to Control Module References in Body Control System for the applicable Diagnostic System Check | -- | |||
8 |
Did you find and correct the condition? | Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 9 | ||
9 | Test the DLC ground circuit at terminal 5 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 10 | ||
Did you find and correct the condition? | Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 11 | |||
Test the class 2 serial data circuit between the DLC and the splice pack - SP205 for an open, a short to ground, or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Control Module References in Body Control System for the applicable Diagnostic System Check | Go to Step 12 | |||
Does the scan tool communicate with the BCM? | Go to Step 16 | Go to Step 13 | |||
Does the scan tool communicate with the BCM? | Go to Step 14 | Go to Step 15 | |||
14 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 34 | ||
15 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 34 | ||
Does the scan tool communicate with the BCM? | Go to Step 21 | Go to Step 17 | |||
17 |
Does the scan tool communicate with the BCM? | Go to Step 19 | Go to Step 18 | ||
18 | Repair the class 2 serial data circuit for a short to ground or a short to voltage between the splice pack - SP205 and the splice pack - SP207. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | -- | ||
19 | Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP207 until the concern is located:
Does the scan tool communicate with the BCM? | Go to Step 36 | Go to Step 20 | ||
20 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 34 | ||
Does the scan tool communicate with the BCM? | Go to Step 28 | Go to Step 22 | |||
22 |
Does the scan tool communicate with the BCM? | Go to Step 34 | Go to Step 23 | ||
23 | Test the class 2 serial data circuit between the splice pack - SP205 and the radio for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find the condition? | Go to Step 36 | Go to Step 24 | ||
24 |
Does the scan tool communicate with the BCM? | Go to Step 26 | Go to Step 25 | ||
25 | Repair the class 2 serial data circuit for a short to ground or a short to voltage between the splice pack - SP205 and the splice pack - SP206. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | -- | ||
26 | Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP206 until the concern is located:
Does the scan tool communicate with the BCM? | Go to Step 36 | Go to Step 27 | ||
27 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 34 | ||
Does the scan tool communicate with the BCM? | Go to Step 32 | Go to Step 29 | |||
29 |
Does the scan tool communicate with the BCM? | Go to Step 34 | Go to Step 30 | ||
30 |
Does the scan tool communicate with the BCM? | Go to Step 34 | Go to Step 31 | ||
31 | Repair the class 2 serial data circuit between the splice pack - SP205 and either the EBCM or TCSCM for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 36 | -- | ||
Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP205 until the concern is located:
Does the scan tool communicate with the BCM? | Go to Step 36 | Go to Step 33 | |||
33 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 34 | ||
34 | Inspect for poor connections at the class 2 serial data circuit of the last disconnected module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 35 | ||
35 |
Important: Perform the module setup procedure if required. Replace the last disconnected module. Refer to Control Module References in Body Control System for the appropriate repair instructions. Did you complete the replacement? | Go to Step 36 | -- | ||
The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn OFF the scan tool prior to performing this test. Did you record any DTCs which begin with a "U" and with a current status? | Go to Step 38 | Go to Step 37 | |||
Did you record any DTCs which do not begin with a "U"? | Go to Step 38 | Go to Step 40 | |||
38 | Diagnose the DTCs as directed by the diagnostic procedures for the particular module or malfunction. Refer to Control Module References in Body Control System for the applicable Diagnostic System Check. Did you complete the action? | Go to Step 39 | -- | ||
39 | Did you diagnose all of the DTCs? | Go to Step 40 | Go to Step 38 | ||
40 | Use the scan tool in order to clear the DTCs. Did you complete the action? | System OK | -- |