Herro

Back at it, trying to finally put a P0410 to rest.

- Air Pump whines and puts out air
- wiring tests good from solenoid to PCM
- Get B+ when key is IG-ON before starting
- I haven’t seen any cracking or pinch in my hose, seems fine
- Pulled original solenoid and replaced with a new one that tested good before install. I don’t recall if the original tested good (was a while back sorry)

So as far as I can tell this should all work, yet I get no vacuum at the control valve. I can “cheat” the code by pulling roughly 10psi at the valve with my vacuum pump, so my assumption is the new solenoid is already done or some voltage issue.

Hence my question. I pulled the blue connector and tested voltage to this solenoid as I started the car today. 14.5V while the Pump ran. Then dropped to 13.8 as it shut off and engine warmed up.

Should this not be 0V when the pump shuts off?

My understanding based on the DIY for testing here, the service manual, and how this system functions that this solenoid should only get voltage while the pump is running? Am I wrong?

Anyways, trying to see if the PCM is sending constant B+ to the solenoid and burning it up. Need to pull this one again (yay) and check, but wanted to ask this as well.

Thanks

 

Did you check continuity of the ground wire from the connector? Because it won’t matter if you have power on one side and no ground on the other. The wires are really small and known to become brittle/fragile with age. It seems like that might be it based on your description, but potentially that ground node in the pcm could be bad or burned out. That’s not likely compared to the wiring issue imo.

I suppose the other thing is; did you verify the vacuum supply tank is actually holding vacuum? Because even if the solenoid opens, it won’t matter if there’s no vacuum from the supply source.
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Hey Team, thanks for the reply!

I did check my ground continuity before; I get open on the power side (well, high resistance), and then continuous on what should be the ground side. I did check it again just now, pull about 30ohms on that side, but I don’t know how it routes through the PCM so that could be normal.

Now I did not think to check the vacuum chamber...that should have been obvious. Pulled it apart it again and hooked it up to my pump. It wouldn’t say it holds, but it takes a solid two minutes to lose 20psi. I will have to pressurize it somehow and see if I can find any leaks.

I did check the solenoid(s) again cold and they were all good.

So unless I missed something here, I guess the chamber could be the issue. I need to confirm what vacuum we should be pulling through there, but maybe it simply can’t build up vacuum in time.

Edit (next day):
So I said all this; started putting together a little pressure device with a smoke option this afternoon. Then decided to test the vacuum on the box again.

May have just gotten a better seal on the three solenoid holes this time...but it seemed to hold about 20psi just fine. Left it for five minutes with no drop.

Plan to still pressure test anyways since it is out. But now I am stumped. I should be getting something down that line to the control valve I would think.