On a 2005 mazda b4000 can i test continuity for the evap system from the pcm? I had the box up and no voltage at the vapour can solenoid. Codes p0453 and p0446.

initially i thought it was a vacuum leak but after pressuring the tank via a wet rag and hose technique suggested in an old thread it seems to hold pressure....

im stumped

 

Yes you can but wiring is a bit convoluted

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction
P0453 Evaporative Emission Control System Pressure Sensor High Input

P0446 is a "circuit" code so device or wiring issue, the computer sees voltage passing thru a device via the wires, so if there is no or lower voltage it will set a "Circuit" code, this can be a fault in the device itself or in the wiring, you can usually test a device with OHM meter, to see it its connected inside, can pass voltage, and for some devices you can find OHM acceptable ranges for that device

P0453 is a "parameter" code the sensor is working but its data is out of range, in this case reading higher than it should, this can be a sensor fault but usually not, it would be a fault in another part of the same system causing the "parameter" code

Here are the 4 engine/PCM wiring diagrams for a 2005 V6 Ranger, 4cyl should be the same as far as EVAP system
I can only post 2 at a time

 

Sensors generally use 5volts from PCM
Valve/solenoids use 12volt key on from PCM relay in most cases

The other 2

 

Well that looks confusing lol

thanks for the info

 

Yes, looks confusing at first, but its just like a road map

Find a device you want to check and follow the wire/road to its next "stop" or all the way PCM

Devices often share positive volts and have a ground that runs back to the PCM that's used for control(valve/solenoid) or for data(sensors)

page 2 has the purge valve and vent valve wiring, when wire goes off the page there will be a number, same number will be on next page to match wire, until you get to PCM or termination of that wire

 

Jumping in here late, but found this thread to be helpful with the persistent P0453 (gurrrrrrr), on my 2004 Ranger XLT 4WD 4.0l. Been reading a lot and have changed the gas cap after sanding a tiny amount of corrosion on the sealing surface and changed the EGT sensor, didn't help but the old one sounded kind of 'loose' and the new one did not rattle. I would clear the code and it would return almost immediately, SO after seeing a number of posts' that said to continue to try clearing the code more than a few times, so today while running errands I left my scan tool plugged in cleared it after getting gas, (No 'whooshing' noise when opening tank), started up and no code, drove 11 miles and stopped, started back up and there was the code, cleared it and drove 5 miles, same situation for three more cycles. Got home, cleared the codes and restarted with no code right away. Sound familiar to anyone? Your insight would be appreciated.