I know, I know, there is a world of archived info out there and I have read much of it however there is something I'm not clear on...

Am planning to endeavor going down the troubleshooting road on my door lock issue. When testing with the MityVac, should the motor be running?

Thanks. You guys rock!

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Dale

The Mityvac provides a similar function to the engine driven vacuum pump.

So, with the Mityvac, you don't need the engine running to perform all your tests.

Thanks Brian for that speedy reply!

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Dale

There is a very good and reasonably clear trouble shooting procedure in the manual for testing the vacuum system.

Len

If you simply want to test for a leak in, say, the central locking system, or if you want to test the function of a specific system component (vacuum module), you would just disconnect the portion of the system you are testing, and pull a vacuum with the mity vac. Then you would observe if the component functions properly (for example if the doors unlock), or observe if the system holds vacuum (if it doesnt hold vacuum you have a leak somewhere). You do not need the car running for this.

But on the other hand if you want to just use the mity vac as a simple vacuum gauge (no pumping the handle, just read the gauge), you would usually
need the car running for these types of tests....the types of things you would do this on, for example, would be to 1) see how much vacuum the vacuum pump draws, 2) to check the function of one of the electronic vacuum control valves, 3) to see if you get vacuum at the shut off valve (on the injection pump) when you turn the car off, 4) install a "t" in a line to which you connect the mity vac, and run the car and read the vacuum, etc. etc.

The mity vac is just a simple tool that does two main things...1) it pulls a vacuum, 2) it reads vacuum. There are many, many specific tests you might do depending on the particular system and specific function you are testing. It is essential that you get detailed vacuum drawings for your vehicle to see how each system works, especially for systems that are very tricky (automatic climate control, with its row of electric vacuum switches and vacuum modules that control flaps).

In the end, you will see that all of these systems are actually pretty straightforward, and testing involves disconnecting, blocking lines, isolating components, pulling vacuum, reading vacuum, etc...

good luck,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)