Diagnostic Aids
Check for the following conditions:
- Poor connection at the ECM. Inspect harness connectors for the following conditions:
- Backed-out terminals.
- Improper mating.
- Broken locks.
- Damaged terminals.
- Poor terminal-to-wire connection.
- Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the Fuel Tank Vacuum Pressure display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.
- Incorrect purge or vacuum source line routing. Verify that the source vacuum and purge lines to the EVAP canister purge valve are not switched.
DIAGNOSIS CHART
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Perform an ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK
. Is the check complete? |
- | Go to Step 2 | Go to ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK . |
| 2 |
Are any Diagnostic Trouble Codes (DTCs) set? |
- | Go to applicable DTC table. | Go to Step 3 |
| 3 |
Is the voltage near the specified value? |
5 V | Go to Step 6 | Go to Step 4 |
| 4 | Check the 5 volt reference circuit for a poor terminal connection at the Engine Control Module (ECM). Is a problem found? |
- | Go to Step 12 | Go to Step 5 |
| 5 | Check for an open 5 volt reference circuit to the fuel tank pressure sensor harness connector. Is a problem found? |
- | Go to Step 11 | Go to Step 9 |
| 6 |
Is the voltage between the specified values? |
1.3 - 1.7 V | Go to Step 7 | Go to Step 14 |
| 7 | Check the fuel tank pressure sensor signal circuit for a poor terminal connection at the ECM. Is a repair necessary? |
- | Go to Step 12 | Go to Step 8 |
| 8 | Check the fuel tank pressure sensor signal circuit between the fuel tank pressure sensor connector and the ECM for an open, short to ground, or short to voltage. Is a repair necessary? |
- | Go to Step 13 | Go to Step 15 |
| 9 | Check the sensor ground circuit for a poor terminal connection at the ECM. Is a repair necessary? |
- | Go to Step 12 | Go to Step 10 |
| 10 | Check for an open in the sensor ground circuit. Is a problem found? |
- | Go to Step 13 | Go to Step 15 |
| 11 | Check for a poor circuit terminal connection at the fuel tank pressure sensor connector. Is a repair necessary? |
- | Go to Step 12 | Go to Step 14 |
| 12 | Repair the malfunctioning harness connector terminals. Is the repair complete? |
- | System OK | - |
| 13 | Locate and repair the open/short circuit in the wiring harness. Is the repair complete? |
- | System OK | - |
| 14 | Replace the fuel tank pressure sensor. Is the repair complete? |
- | System OK | - |
| 15 | Replace the ECM. Is the repair complete? |
- | System OK | - |