Fuel pump running with truck off

Great stress relief!. Just noticed my 15 doing it for the first couple times today. Right about 5 hours later. Can't believe I've never noticed this. Great post!

 

I've had my truck for five years now and have never caught it doing this but I did hear my wife's 2015 Corolla doing it the other night. Fortunately, I've seen these threads before.
Yes, perfectly normal. And yes, it's an old thread.

 

Hey, does anybody know how to disable this feature, or to create a condition where this check does not occur? -- I go car camping a lot, and I sleep in the truck bed in a camper shell. This stupid goddamn fuel evap check always kicks on in the middle of the night and wakes me up. I would LOVE to be able to disable this thing so it doesn't kick on and wake me up in the middle of the night. -- 2014 4 cyl 2.7 --- P.S. I live in Utah, no state inspection here, so I'm not concerned about passing/failing emissions inspection.

 

the motor is powered by the ECM. best way to disable would just be to unplug the connector at the canister.

 

...And have a permanent CEL unless you "tune" it.

 

Yep, Im assuming he'd be ok with that being that it was stated no emissions inspection there.

 

Probably but just making sure he's aware, with CEL on for a EVAP code you won't know if any other issues pop up unless you do regular code scans. also likely will have a Trac off light on as well.

 

Thank you both for your responses! -- Have had a look at the canister and pulled out the plug (CEL and TRAC OFF, just as you said). The connector plug looks as though it has 5 wires coming in (didn't get a great look, it was getting dark, my glasses suck, didn't take note of the wire colors, I will look more closely tomorrow). Let's say I wanted to splice in, run wiring to the camper bed, and wire a toggle switch so I could power off and on as I please. Would it be possible to do that on only one of the wires (power coming in), or maybe two? and thus avoid having to splice and run all 5 wires? I tried to find a wiring diagram online, but no luck so far.

 

I'd suggest interrupting the ground of the pump, terminal #6 of the L1 connector.

 

You would still get a CEL but yes you could just interrupt that single wire.
@6 gearT444E what if one were to temporarily interrupt the EFI 10A fuse, would that prevent it from running the test without flagging a code?

 

Excuse me butting in, but I think EFI 10Amp fuse just powers the Vent Valve doesn't it?

The pump motor is powered via MTRB Pin 1 Green Wire from the ECU MPMP pin # 6 from what I am seeing.

 

Pulling the 10A EFI No. 2 fuse may accomplish the same thing as the pump won't have any power, but it looks like the pump takes power from the ECM, which also gets power from the 20A EFI no. 1 fuse so I'm not sure if pulling that fuse would prevent the pump from running or not. Even so, if the fuse is pulled or the pump motor was interrupted via a switch, the test would still fail and a MIL would be stored in the ECM. Personally, I'd rather have the switch, as to keep pulling that fuse out can cause connection issues in the long run.

Yes, it is powered from MTRB, but I was suggesting to interrupt the ground rather than the +12V to the motor, less risk of a fuse blowing if a short occurs in the wiring. The vent valve is powered via the 10A EFI No. 2 fuse and the ECM switches the ground via the VPMP pin.

 

@Jimmyh @Dm93 @6 gearT444E

You guys know more than I.
Is it possible that if we interrupt the Soak Timer, we could stop the EVAP Test?
As Dm93 said, pull the EFI cut power to the IC of the ECM that powers the Soak Timer?

Or maybe, this isn’t at how it works.

 

the soak timer is integral to the ECM, so yes in theory you could cut power to it, but you’d be killing power to the whole ECM. Each time you did this the truck would have to relearn idle curves which would get annoying id think.

another option would be to trick the ECM into thinking the tank level is >90% full or the ECT, or IAT is failed high/low. those are three of the permissives required to start the test. That’s getting to be more work than it’s worth though I think.

 

I’d just turn the ignition on before I go to sleep.
You’d have at least 5 hours before the test starts.

I never sleep longer than 5 hours at a time when camping.
It’s like I wake up every couple hours anyways.

 

yeah you could just do that was well. If you are to interrupt the EVAP test, it will require two failed tests to generate a MIL, so if say you are camping for the weekend it would probably only do 1 test when you parked the truck anyhow. It will show as a pending code until a second time it's checked and confirms the error.

 

Too much work for too little gain in my opinion. I have to wake up to pee too often for that little pump to bother me...

 

Hey all,
First off, 6 gearT444E and others, thank you VERY much for your input and assistance, I appreciate it.

So, I have it all wired up and plugged in, just finished a few minutes ago. I cleared the CEL and TRAC OFF by doing the "trip A, ignition off, restart w/ button held down" (I don't know if that's as official as using a OBD2, but that's all I have right now). Now, when I interrupt the ground (W-B) circuit (both running and off), there is no indication of any fault on the dash lights, nothing comes on. It's just the same as it was before I ever unplugged the connector, regardless of whether or not the circuit is interrupted.
So, can I surmise for the time being, that no fault is detected because the EVAP leakage check is not initiated? Perhaps when the EVAP leakage check initiates (in the middle of the night or whenever), if that circuit is open at that time, a fault will be detected and I will get a CEL (or whatever)? I am bit surprised by this, because when I first unplugged the connector, I got fault indications immediately, but I guess simply interrupting the ground circuit is not the same thing as unplugging all 7 wires to the unit.
Frankly, I don't even care whether or not interrupting this circuit triggers fault lights, as long as it (hopefully) prevents the EVAP leakage check from occurring during that idle period, but I did sort of expect the fault lights to correlate with ground circuit interruption (perhaps I'm wrong about that).

I will now leave the circuit open, and see what happens. I will be pleased (?) if I go out in the morning and see a CEL or some sort of fault indication, indicating that (?) when the EVAP leakage check attempted to initiate, it ran into problems and flagged?

 

You are welcome. The key-off check is only performed several hours after shutdown for pre-determined conditions. So essentially, the ECM isn't looking for motor circuit continuity or test data when the truck is running. With the switch open, I'd only expect you to see a CEL if you met the initiating conditions twice with the switch open as it's a 2 trip detection logic.

I would surmise if you met the conditions, and the test tried to initiate with the ground isolated to the vacuum pump, you will find the following MIL after you go to start the truck again.

When you unplugged the connector, you also disconnected the canister pressure sensor from the ECM, which IS used when the engine is running for the purge flow monitor function. It also checks for a gross fail of the canister pressure sensor (P0452 - Canister pressure sensor (built into canister pump module) voltage low.

 

So, I thought I would report back on how this all went, just so it is here as a reference if anyone else delves into the same or similar situation and project. Also, by the way, this place and you guys are awesome, totally helpful (6 gearT44E especially).

I got everything wired up. I left the switch in an OFF position for the last 2 weeks to test it out, to see A) if I had achieved the desired effect of not having the test occur in the middle of the night, and B) If and when it would trigger fault codes, and what codes it would trigger.

The whole thing seems like a success to me. I only spent one night out camping recently, but I did NOT get any test in the night, and I was able to sleep straight through without interruption, so far so good.
Yesterday, I finally got CEL codes, so I guess it took that long (2 weeks or so) for the 2 trip detection logic to signal for codes. I got, all at once, 14 total code signals, in the form of 5 distinct codes, repeating thru almost 3 cycles.

it looked like this..
1/14 - P043E (evap sys leak detection orifice low flow)
2/14 - P043F (evap sys leak detection orifice high flow)
3/14 - P2401 (esld pump control circuit low)
4/14 - P2402 (esld pump control circuit high)
5/14 - P2419 (evap sys switching valve control circuit low)
then 6 thru 10, exact same codes, same sequence
then 11 thru 14, same codes, same sequence except for no P2419 at the end.

Seems good to me, seems like it tried to run the test twice over the last couple weeks, wasn't able to properly test because of the ground interruption, got confused, and registered and stored a bunch of conflicting codes. Maybe after 2 fails, it tried a third and then finally flagged in the middle of the attempt?

For now, I'm calling it a win.
I'm gonna switch to the ON position, hopefully it goes back to normal, and I can switch it on and off as I please, getting the desired result, possibly never even triggering any codes on the dash as long as I switch it back on every time after I'm done in the backcountry.

Thanks all!