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Hello everyone need some help ......got under truck found canister and vent ,found bed support rusted dropped down on vent solenoid wire and cut through + wire. repaired wire and checked and replaced fuse. drove for few days code did not clear so pulled vent and tested off battery ,solenoid works closes vent . started truck used test light getting + voltage when light camped on frame for ground.. rigged up paper clips in plug contacts, put test light between to test , no light .Using multimeter did a continuity test from wire connectors that are mounted by fuel filter under drivers side door area ,show continuity from there back to vent solenoid. Hooked up a long wire from pos+ battery post back to canister vent solenoid and hooked test light between it and neg - side of connector ...no light .Trying to find out if there should be pos + volt supply to vent solenoid and other wire is a chassis ground.,if so i have lost the connection , or is it possible that it is a neg - that signal is controlled by PCM and it is failing at PCM.have had no luck tracking down a wire diagram. Had thought about just splicing in a new ground but with out a diagram to see how it should be wired I didnt want to risk casing further damage . Thanks for any help
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Thank you Chad that confirms what I was thinking how it worked . Is there any other items that fall under the P1451 , or is it specific to canister vent . I was thinking maybe the vent solenoid issue has been taken care of but there is another issue causing the check engine light not to clear ,like gas gap not sealing causing leak and system not able to pressurize . Also how does the system work what has to happen to make PCM energize solenoid and close vent , and is there a way that I can test to see if the PCM is grounding the purp/white wire . Thank You
Do you have a bidirectional scan tool where you can control the valve? That would be ideal here.
With the valve in it's normal off state, you should have 12v on both sides of the connectors, all the way from that fuse, through the solenoid, to the ECM. With the valve on, you should have near battery voltage on the power side and near 0v on the ground side (or less than .5v). If these are both the case, the wiring is God and component is good.
You can "be the computer" and use your test light to go from the ground side of the valve connector to a known good ground and see if the valve operates. You aren't looking for the light to turn on here, just for the valve to operate. This will tell you if the valve is good and the power side of the circuit is good.
After typing all of that, I think I remember you said you bench tested the valve and it worked...
You really want to have the valve in its original place and activated to check wire integrity on both sides of the circuit. Looking for that near zero volts on the ground side now, after providing the ground with your test light. If the valve is good, the wires are good, that only leaves the ECM. To condemn the ECM, I'd really want to be able to bi-directionally control it though with the codes erased. I'm not sure if you'll ever be able to catch the valve closed to be able to do the test with out that scantool.
Anyone else have any ideas on how to go about this?
It's possible that the ECM valve driver is shut down until the code is cleared.
set it up tested in position canister vent solenoid working got code cleared , put 80 miles on and no check engine light ,will put another 40 miles on tomorrow if no engine I will assume repair was good .Thank You for help
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