Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
- The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
- Unlike the UART serial data circuit, the only time a Class II serial data circuit has any voltage on it is when a scan tool asks the ECM for information and sends the information out.
- (5) Locate and repair any shorts that may have caused the fuse to open before replacement, if the no voltage condition was due to an open fuse.
- (10) The scan tool or associated cables could be malfunctioning. Refer to the scan tool's manual for repair information.
DIAGNOSTIC PROCEDURE
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Perform an On-Board Diagnostic (OBD II) system check. Was the check performed? |
- | Go to Step 2 | Go to "ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK :" |
| 2 | With a test light connected to the ground, probe the Data Link Connector (DLC) battery feed terminal 16. Is the test light illuminate? |
- | Go to Step 4 | Go to Step 3 |
| 3 | Repair an open or short to ground in the DLC battery feed circuit. Is the repair complete? |
- | Go to Step 4 | - |
| 4 | With a test light connected to the battery, probe the DLC ground terminal 4 and 5. Is the test light illuminate? |
- | Go to Step 6 | Go to Step 5 |
| 5 | Repair an open circuit. Is the repair complete? |
- | Go to Step 6 | - |
| 6 |
Does the scan tool power up? |
- | Go to Step 8 | Go to Step 7 |
| 7 | Check for damages in the terminal of DLC and scan tool, and repair as needed. Is the repair complete? |
- | Go to Step 8 | - |
| 8 | Using a scan tool, request engine data of Engine Control Module (ECM). Does the scan tool display any data? |
- | Go to Step 12 | Go to Step 9 |
| 9 | Install the scan tool on another vehicle and check for proper operation. Does the scan tool work properly on a different vehicle. |
- | Go to Step 11 | Go to Step 10 |
| 10 | The scan tool is malfunctioning. Refer to the scan tool's manual for repair. Is the repair complete? |
- | Go to Step 12 | - |
| 11 | Repair communication circuit between ECM and DLC. Is the repair complete? |
- | Go to Step 12 | - |
| 12 |
Does the engine and continue to run? |
- | Go to Step 13 | Go to Step 2 |
| 13 |
Are any DTCs displayed that have not been diagnosed? |
- | Go to "APPLICABLE DTC TABLE " | System OK |