Circuit Description
This diagnostic is performed as part of the purge solenoid diagnostic inhibit criteria and will detect a diagnostic vacuum switch stuck in the open (high vacuum) position.
Conditions for Setting the DTC
| • | The ignition is ON and the engine is OFF. |
| • | The EVAP purge pressure switch state is "High". |
| • | This diagnostic runs once per ignition cycle. |
Action Taken When the DTC Sets
The VCM turns the MIL ON after 2 consecutive driving cycles with the fault active.
Conditions for Clearing the MIL/DTC
The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used.
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.
Check for the following:
| • | Poor connection or damaged harness -- Inspect VCM-A harness connectors for backed out terminals "BL12" and "GR15" improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness. |
| • | Intermittent test -- If connections and harness check OK, monitor a digital voltmeter connected between VCM-A terminal "GR15" and "BL12" while moving the related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction. |
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||||||||
1 |
Important: Before clearing the DTCs, use the scan tool to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | Go to Step 2 | |||||||
2 | With the engine idling, the Tech 1 should display EVAP Purge Pressure Switch to be OFF. Does it? | Go to Step 3 | Go to Step 6 | ||||||
3 |
| Go to Diagnostic Aids | Go to Step 4 | ||||||
4 |
| Go to Step 9 | Go to Step 5 | ||||||
5 |
| Go to Step 7 | Go to Step 8 | ||||||
6 |
| Go to Step 9 | Go to Step 8 | ||||||
7 | Check circuit 451 for an open or poor connection to ground. Did you find and correct the condition? | Go to Step 13 | -- | ||||||
8 | Check circuit 928 for an open or a short to ground. Did you find and correct the condition? | Go to Step 13 | Go to Step 10 | ||||||
9 | Check the EVAP Purge Pressure Switch connector for a poor or intermittent connection. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 l switch | ||||||
10 | Check the ECM connector for a poor or intermittent connection. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 | ||||||
11 | Replace the EVAP Purge Pressure Switch. Did you complete the replacement? | Go to Step 13 | -- | ||||||
12 | Replace the VCM. Refer to VCM Replacement/Programming . Did you complete the replacement? | Go to Step 13 | -- | ||||||
13 |
Does the scan tool indicate that this diagnostic ran and passed? | Go to Step 14 | Go to Step 2 | ||||||
14 | With a scan tool, select Capture Info in order to observe the stored information. Does the scan tool display any DTCs that you have not diagnosed? | Go to the applicable DTC table | System OK | ||||||
