P1653

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The EGR flow is controlled by the vacuum actuated EGR valve. The EGR vent solenoid purges to atmosphere the vacuum level at the EGR valve actuator as commanded by the PCM. This is done when the EGR flow is desired to turn off quickly. When the PCM is commanding the EGR vent ON, the voltage potential of the circuit will be low (near o volts). When the PCM is commanding the EGR vent OFF, the voltage potential of the circuit will be high (near battery volts). The primary function of the PCM in this circuit is to supply the ground for the EGR vent solenoid.

Conditions for Setting the DTC

^ PCM requested EGR vent ON.

^ Voltage on EGR vent control circuit high (near battery volts).

^ Conditions met for 2 seconds.

or

^ PCM requested EGR vent solenoid OFF.

^ Voltage on EGR vent control circuit low (near

o volts).

^ Conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.

^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL off after three consecutive trips without a fault condition.

^ A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

^ Use of a Scan Tool

Diagnostic Aids

The scan tool has a 5 second ON time abort. The EGR vent solenoid can be commanded ON for as many times as needed, in 5 second intervals. Its possible other EGR DTCs may set along with DTC P1653. This diagnostic can be checked at key up. A quick operational check can be made by commanding the EGR vent solenoid ON and OFF with the scan tool while monitoring Actual EGR. Actual EGR will display Barometric pressure (BARO) (approximately) when EGR solenoid is OFF.

The Adaptive Learn Matrix (ALM) is used to adjust the EGR vacuum control based on Mass Air Flow (MAF). The ALM may change as a result of back

pressure increases over the life of the vehicle or other engine system variations. The ALM is made up of sixteen cells (numbered from zero to fifteen) in which each cell covers a range of engine speed (RPM) and load (mm3).

An intermittent may be caused by the following:

^ Poor connections.

^ Rubbed through wire insulation.

^ Broken wire inside the insulation.

Test Description

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

2. Be sure that both the ON and OFF states are commanded. Repeat the commands as many times as necessary.

3. This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may open (Amps drop to zero, or short (Amp draw greater than 0.75 A).

7. Listen tor an audible click when the solenoid operates.