Evaporative Emission Control System Diagnosis. Oldsmobile Silhouette Ext. 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Silhouette Ext. 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 Evaporative Emission Control System Diagnosis

Refer to

EVAP Control System Overview


(1)	EAVP Vent Valve/Solenoid
(2)	EVAP Vent Valve/Solenoid Ignition Feed Circuit Terminal
(3)	EVAP Vent Valve/Solenoid Control Circuit Terminal
(4)	EVAP Vent Valve/Solenoid Filter
(5)	EVAP Vapor Lines
(6)	Fuel Tank Pressure Sensor
(7)	Fuel Tank Pressure Sensor Ground Circuit Terminal
(8)	Fuel Tank Pressure Sensor Signal Circuit Terminal
(9)	Fuel Tank Pressure Sensor Circuit 5 Volt Reference Circuit Terminal
(10)	Fuel Filler Pipe
(11)	Modular Fuel Sender Assembly
(12)	Fuel Limiter Vent Valve (FLVV)
(13)	Pressure/Vacuum Relief Valve (Optional)
(14)	EVAP Canister
(15)	EVAP Canister Purge Valve/Solenoid Ignition Feed Circuit Terminal
(16)	EVAP Canister Purge Valve/Solenoid Control Circuit Terminal
(17)	Intake Manifold Vacuum Source
(18)	EVAP Canister Purge Valve/Solenoid
(19)	EVAP Service Port

Circuit Description

The evaporative system includes the following components:

•	The fuel tank

•	The EVAP vent solenoid

•	The fuel tank pressure sensor

•	The fuel pipes and hoses

•	The vapor lines

•	The fuel cap

•	The evaporative emission canister

•	The purge lines

•	The EVAP purge solenoid

The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the solenoid valve (purge ON). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. The duty cycle is calculated by the PCM and the output is commanded when the appropriate conditions have been met.

The EVAP Vent solenoid is used to seal the EVAP system during the EVAP leak diagnostic tests. The fuel tank pressure sensor is used to monitor vacuum in the system during the diagnostic tests.

A stuck closed EVAP purge solenoid, stuck open EVAP vent solenoid, disconnected or damaged EVAP purge line or vent hose, leaking fuel cap, or fill neck should set a DTC P0440 Evaporative Emission (EVAP) System . A small leak in the EVAP system should set a DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected An EVAP vent solenoid stuck closed, a restricted vent hose, or a blocked EVAP canister should set a DTC P0446 Evaporative Emission (EVAP) Vent System Performance . A continuous purge condition with no purge commanded by the PCM (EVAP purge solenoid stuck open or leaking) should set a DTC P.O.W. EVAP System Flow During Non-Purge. Refer to the DTC tables for further diagnostic procedures regarding the EVAP system.

Diagnostic Aids

Check for the following conditions:

•	Poor connection at PCM

•	Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•	Damaged harness

•	Inspect the wiring harness for damage. If the harness appears to be OK, observe the Fuel Tank 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 malfunction.

•	Incorrect EVAP purge or vacuum source line routing

•	Verify that the source vacuum and EVAP purge lines to the canister purge valve are not switched.

Important: Although these diagnostics are considered type A, they act like type B.A. diagnostics under certain conditions. Whenever the EVAP diagnostics report that the system has passed, or if the battery has been disconnected, the diagnostic must fail during two consecutive cold start trips before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

The powertrain OBD System Check Paramus you to complete some of the basic checks and store the freeze frame and failure records data on the Scan Tool if applicable.

If a vent valve or EVAP purge valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction that caused the DTC to set will very likely correct the condition.

Checks for a fuel tank pressure sensor stuck high condition. The scan tool should read within +/- 1.0 in. H2O of the specified value.

Checks for a large leak in the EVAP system.

Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes. The EVAP station is pressurizing a sensor that normally reads vacuum. The tech II reads high pressure at 0 volts and high vacuum at 5 volts. The tech II can only read a max pressure of 6.0 in. of H2O (0 Volts). However the EVAP service station can pressurize the system to much higher pressures. The scan tool value should be within +/- 0.5 of the specified value.

Checks for a stuck closed EVAP Vent Valve/Solenoid. The value should decrease to within +/- 1.0 in. Hg of the specified value.

Checks for a leaking or stuck open EVAP canister purge valve/solenoid. The scan tool should read within +/- 1.0 in Hg of the specified value.

Ensures that sufficient source vacuum is present at the EVAP canister purge valve/solenoid.

Checks for a small leak in the EVAP system.

Enhanced Evaporative Emission System Check

Step

Action

Value(s)

Yes

Was the Powertrain OBD System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Important: : Visually/physically inspect for the following conditions:

•	Vacuum or purge lines disconnected--Refer to Emission Hose Routing Diagram .

•	Loose or missing fuel fill cap

Is DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit or DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit also set?

0 in. H2O

Go to the other DTC first

Go to Step 3

Ignition Switch OFF.
Remove the fuel fill cap. This will relieve the fuel tank pressure.
Ignition Switch ON, Engine OFF.
Observe Fuel Tank Pressure on the scan tool.

Is the Fuel Tank Pressure at the specified value?

0 in. H2O

Go to Step 4

Go to DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage

Important: Before continuing with diagnosis, zero the EVAP Pressure and Vacuum (inches of H2O) gauges on the
Object Number: 20803 Size: SH


(1)	Main Valve
(2)	Evaporative Emission System Purge/Presure Diagnostic Station J 41413
(3)	Nitrogen Cylinder
(4)	Black Connecting Hose
(5)	Threaded Fitting
(6)	Gauge Set

EVAP pressure/purge diagnostic station.

Important: Do not exceed the pressure in the specified value.

Ignition Switch OFF.
Reinstall the fuel fill cap.
Connect the EVAP station to the EVAP service port.
Ignition Switch ON, Engine OFF.
Capture Fail Record data for DTC P0440 and clear DTCs.
Using the scan tool, EVAP Purge/Seal, select seal option to seal the EVAP System.
Attempt to pressurize the system to the specified value by slowly turning the EVAP Service Station rotary switch to the "pressure" position (monitor the pressure with the rotary switch in the "Off/Hold" position).

Can specified value be achieved?

5 in. H2O

Go to Step 5

Go to DTC P0440 Evaporative Emission (EVAP) System

Maintain the Fuel Tank Pressure at the specified value (monitor the pressure with the rotary switch in the "Off/Hold" position).
Observe Fuel Tank Pressure on the scan tool.

Is Fuel Tank Pressure at the specified value?

5 in. H2O

Go to Step 6

Go to Step 10

Command the Vent Valve/Solenoid OFF (open) to relieve the pressure through the Vent Valve.

Does the EVAP pressure gauge decrease to near the specified value within 2 minutes with the rotary switch in the "OFF/Hold" position?

-5 in H2O

Go to Step 7

Go to DTC P0446 Evaporative Emission (EVAP) Vent System Performance

Connect the in. Hg vacuum gauge on the EVAP Service station to the Purge valve/solenoid canister side.
Ignition Switch ON, Engine OFF.
Using the Scan Tool, EVAP Purge/Seal, select the seal option to seal the EVAP System.
Start the engine and idle.
Run the engine from 1200-1500 RPM and observe the vacuum level.

Is the vacuum level near the specified value?

0 in. Hg

Go to Step 8

Go to Step 11

Using the scan tool, increase purge to 100%.
Run the engine from 1200-1500 RPM and observe vacuum level.

Is vacuum level above the specified value?

15 in. Hg

Go to Step 13

Go to Step 12

Check for a kinked or restricted canister purge line between the EVAP canister purge valve and EVAP canister.
Repair the canister purge line as necessary.

Is the action complete?

Go to Step 13

Visually/physically check for the following conditions:

•	Restricted fuel tank vapor line

•	Restricted EVAP purge line

If a problem is found, repair as necessary.

Was a problem found?

Go to Step 13

Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage

Important: Check for carbon release into the EVAP system. Refer to diagnostic aids.

Replace the EVAP canister purge valve/solenoid. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Is the action complete?

Go to Step 13

Check for no source vacuum to the EVAP purge valve.
If a problem was found repair as necessary.

Was a problem found?

Go to Step 13

Go to Step 12

Important: Do not exceed the pressure in the specified value.

Reconnect all EVAP hardware that was previously disconnected.
Ignition switch ON, Engine Off.
Using the scan tool, EVAP purge/seal select the seal option to seal the system.
Pressurize the system to the first specified (higher) value by slowly turning the EVAP Service Station rotary switch to the "pressure" position (monitor the pressure with the gauge on the cart with the rotary switch in the "Off/Hold position).

Does the EVAP pressure decrease to less than the second specified (lower) value within 2 minutes with the rotary switch in the "Off/Hold" position?

15 in. H2O

10 in. H2O

Go to DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

System OK