Enhanced EVAP Functions

By monitoring tank pressure, the M96.5 and later TRIONIC ECM is able to determine that the basic purge function is working AND detects the presence of any vapor leaks in the fuel supply system from the filler cap to the intake manifold. First, a review of the hardware used to accomplish this:

Tank Pressure Sensor

This sealed three wire sensor is mounted on the tank filler pipe above the rear axle. The output from this sensor may be monitored with Tech 2 or ISAT by selecting "READ FUNCTIONS-TANK PRESSURE". The possible range of readings is +/- 3.0 kPa, in normal operation the display will be close to 0 and the readings will be in tenths of kPa. (For example: 0.3 kPA).

Canister Close Valve (CCV)

The canister close valve is a NORMALLY OPEN two wire solenoid valve whose function is to control the flow of purge air into the charcoal canister The main relay supplies this valve with power and the ECM provides a ground. For the vast majority of the time this valve is wide open and only closes for a few seconds when the enhanced diagnostic routine runs. The valve is connected to the canister by a short length of hose and is located between the fender liner and outer fender above the right front wheel.