[T3] J16 relay ????

Jim Adney jadney at vwtype3.org
Fri Aug 9 22:14:07 PDT 2013


On 10 Aug 2013 at 4:22, Daniel K. Du Vall wrote:

> OK I probably wired something wrong but I am using the existing (J16
> (Power supply relay for fuel injection) in my Megasquirt  conversion.
> I left most the wiring the same except for the ones that used to go to
> J21. I know my setup is not stock but is there a reason that this
> relay would not turn off after the engine is started and then the key
> is turned off? IT functions correctly as long as the engine is not
> running.  Or did I miss understand what this really was used for in
> its original setup? 

J16 is the FI main power relay. It should get power only from the 
ignition switch. If it doesn't shut off when you turn the key off, 
check for voltage at that terminal. Unplug that terminal and see if 
the relay then opens. It should. If it doesn't, the relay is 
sticking. if there's voltage on that terminal, it's being supplied 
from somewhere else. It's odd that they show wires leading to J21, 
because those wires just lead to the FI brain. There's no other relay 
there.

It sounds like you might be getting power from the generator that 
holds the relay on when the key is off, but there should be no path 
for that to happen. The J16 relay coil should not get any power once 
the key is off.

It's always possible that the relay is sticking, or that there's a 
problem with the ignition switch.

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