[T3] B brain

[Jim Adney]

On 2 Jun 2018 at 22:44, Jim Adney wrote:

> On 2 Jun 2018 at 13:36, Mark Reno wrote:
> 
> > Cool. I do recall the voltage being low. The book says if terminal 18 on
> > the brain is not getting a ground than it should be replaced. What do you
> > think?
> 
> Terminal 18 goes to the starter and is not a ground.
> 
> You must mean terminal 19. Terminal 19 PROVIDES a ground for the fuel 
> pump relay. If the pump relay is not closing for ~1 sec when you turn the key 
> ON, there are a number of possible causes. A bad brain is only one 
> possibility.
> 
> What are your symptoms? Do you hear the relay under the dash click when 
> you turn the key ON?

Here's a simple test you should do to see if a lot of the FI system 
is working properly:

Turn the key ON. As the key comes on you should hear a relay click. 
This is actually 2 relays, one under the back seat and one under the 
dash, coming on at the same time. Since they come on at the same 
time, you will hear what sounds like a single click.

About 1 second after you turn the key ON, you should hear a second 
click. That's the relay under the dash turning off because nothing 
happened after 1 second.

If you hear both clicks, you've checked a lot of the FI system. The 
brain is getting power and ground, and the fuel pump relay is being 
operated properly.

As a bonus, if you can hear the fuel pump buzz for that 1 second, you 
also know that the fuel pump wiring is good and that the pump motor 
is at least running. (This does NOT guarantee that it's actually 
pumping.)  

You may need a second person to listen for the pump with an ear near 
the RF wheel.  

Do this test and let us know what you hear.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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