Looking for a little bit of assistance. A while back I popped a P0453 code. I found the electrical connector going to the charcoal cannister had a few broken wires on it. I don't know if a rock or something flew up and cut them, but they were not clean cuts and some of the insulation on the other wires had some nicks in them. A replacement connector was ordered, but the wire colors were not the same. I spliced each wire one at a time. Connected everything back up and cleared the code and all was right in the world. After a few days of driving the CEL was on again. This time I get a P2420 Evaporative Emission System Switching Valve Control Circuit High (vent valve stuck open (vent)). It will clear, but after a couple of starts it comes back. There is always the possibility I inadvertently swapped a wire when replacing the connector since a few of the wires were already broken. However, I no longer have the old connector to check and make sure I matched up the wires correctly.

Does anyone have a wiring diagram and/or the troubleshooting chart for evap emissions? I found one for an 1st gen, but they used a 10 pin connector vice an 8 pin on the charcoal cannister so the wire locations don't match up.

 

Greetings & Salutations!

You probably did repair OK, this new code is not related to previous one.

Could be you dislodged a vacuum-hose during repair-process. Or vacuum-line was damaged by whatever broke the wiring initially.

Follow test procedure in manual for P2420 and it'll narrow down what issue is. Most EVAP and emissions codes are due to broken/disconnect vacuum-lines and/or plastic T-fittings in system.

 

Thank you for the reply.

I am usually pretty good with wiring and electrical work, but there is always the possibility I goobered something up. I just find it a bit odd that this code wasn't present before I swapped the connector. So my mind instantly goes to me inducing a failure.

I will double check the vacuum lines and the canister itself.

I can't really follow the test procedures from the 1st gen manual. A number of them require checking voltages and resistance. The difference in the pin out of the connectors prohibits that. I could guess that the wire colors are the same between gen 1 and gen 2 vehicles and deduct where the pins are on the connector. However, if I am not getting the correct voltage or resistance values I can't be sure if I am actually taking a reading on the correct pin or if the measured values I get are correct.
Likewise, using the same guess and deduction technique to find the pins that activate the vent valve to manually test it is a crapshhoot. I can do that with a 9 volt battery, but I am a bit apprehensive about applying power to a pin on the cannister that may not like it.

 

Don't worry about wiring colours. Go with terminal positions in connector. Back-probe connector to leave everything plugged in and operational. Then you're testing for voltages yes/no conditions to follow flow-chart. Same with testing vacuums at various valves and junctions.

Usually when they have you apply voltages to test actuators, testing is done with part removed or connector unplugged to isolate just that component.

 

The terminal positions aren't the same between the 1st gen and the 2nd gen. Which is why I mentioned the wire colors and using those to possibly deduct the positions in the 2nd gen connector. Based on the 1st gen wiring diagram I have, it uses a 10 pin connector. Having had the 2nd gen connector in my hand I can confirm it uses an 8 pin connector. The 1st gen has a pin in position 9 which obviously doesn't exist on the 2nd gen.

I completely understand testing the actuators/valves with the connector unplugged or back probing to read voltage etc. I am no stranger to electronics since I have been working in the field since 1990. Having an accurate wiring diagram can be crucial to getting accurate results/readings without inducing (more) failures.