EGR VSV testing

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Aug 21, 2016
I might have revived a cursed thread earlier. Apologies?

Any ideas what my issue is?

I removed throttle body and saw an impressive amount of hardened carbon. Cleaned that all off.

Here's the mystery to me, I removed VSV and tested with ohm meter and applied vacuum and voltage. My factory vsv is behaving just like the new replacement. Both reading about 33 ohms. However, when applying vacuum with no voltage neither hold at all, air passes right through. If I plug the open port, of course it'll hold. My impression is that they should hold vacuum until voltage is applied. Both exhibit a clear audible click with voltage.

Any help would be appreciated. I'm unsure whether to replace the vsv and throw everything back together or use my original because maybe it was the carbon build-up. What are the odds my replacement VSV is malfunctioning the same way my current one is?
The VSV is a normally-open valve.
The VSV is a normally-open valve.
Well that would explain a ton. Thank you.

Just seemed so many posts I searched out treated this video (and others like it) like gospel so I went with it. Maybe I'll try applying voltage then seeing what happens when I create vacuum.

I would refer to FSM but I lost my digital copy and all the links are to the data base (hell of a deal) is no longer active.
Hi all,

This was originally shared by @BirfMark, but his link is dead so I thought I would share a link to the folder in my Google Drive. If you download this locally to you computer, it is fully text-searchable...all 1,399 pages. This FSM covers Engine, Chassis, Body and Electrical. BirfMark also hosted a link to a companion electrical wiring diagram, but I can't find it after a cursory search. If you have it and can share it, that would be awesome. Not hammering on BirfMark for no longer hosting! I'm happy to host the FSM, and the companion electrical diagram, and share a link to my Google Drive. Enjoy.


1996 FJ80 Factory Service Manual (FSM)

As always, for $20 you get 2 days of access to download on toyotas tis. Kind of a pain to download page by page, but an iPad can store so much more info than tons of manuals.
That's the link I couldn't find for the life of me!
Thanks a ton!!!
Thanks again guys. Going through the FSM steps and coming to landcrshr's earlier comment, my vsv would hold vacuum with voltage applied but would not open back up once voltage was removed. However, the replacement seemed to function just fine. 🤞
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I had a 0420 code, and pulled out my VSV to replace it. One the bench, the new OEM VSV and the original into tested identically. That was frustrating.
So, I put in the new one, and no more code or CEL. That was a few years ago.
My conclusion is that the VSV can fail intermittently, and/or can test fine but perform poorly.
Good luck, YMMV.
Mine also went intermittent before total failure.
Hi, I'm testing the VSV on my 94 LC per FSM because I'm getting the error code 28 after driving a few miles. The vacuum gauge is T-connected between the EGR modulator and valve. When I test with hot engine, the vacuum gauge does not move at 2500 rpm with vehicle parked although the procedure says I should see a low vac. But if I drive, the vacuum gauge moves showing low vacuum as seen in attached video. The FSM does not specify to drive the vehicle for this test. Should I assume that my VSV is bad? I also tested with the port R directly connected to the intake manifold (the second hot engine test in FSM)and I did not see any difference although the FSM says I should see a high vacuum with direct connection. Any inputs will be appreciated.
VSV test running 1R.gif
There have been a few people reporting a problem with the EGR VSV intermittent failure. So, I decided to replace the VSV and removed the intake plenum. While I was installing a new VSV, I notice that one end of a short 5mm line is off a tee connector. A close inspection revealed that both ends of this 5mm hose are cracked. I replaced all vacuum lines and the VSV. I've driven for a while and the error code 28 has not returned so far.
Well my CEL is back after a month and about 100 miles and I suspect it might be the generic Dorman 911-609 EGR Vacuum Modulator I tried off of Amazon.

At least I got through the bi-annual smog test. Will try the Toyota unit next after a few more pressing matters around the house.

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