[T3] start issues....

[Jim Adney]

On 12 Mar 2011 at 21:58, Ted Nehring wrote:

> Recent e-mails mentioned a "Ford" solenoid fix..Can anyone provide an
> illustration of the wiring for this install ? 

Routing the solenoid current thru the ignition switch means a long 
wire run and a rather heavy current thru that switch. You can 
alleviate this by installing a relay under the back seat.

Wire the relay so that its coil current is the only current that 
passes thru the ignition switch and the solenoid current goes 
directly from the battery to the relay and then to the solenoid. This 
reduces the wear on the ignition switch and minimizes the distance 
the medium solenoid current has to run.  

You just need to pick a relay that will pass the solenoid current 
without damage. A Ford solenoid relay will work, but it's really 
overkill. OTOH, most other small relays won't have sufficient 
capacity. I think there are some rather small automotive relays that 
are rated at 50 A continuous that should be fine. You should probably 
add a freewheeling diode across the relay coil terminals to minimize 
inductive arcing at the ignition switch.  

The beauty of this solution is that it prevents damage to the 
ignition switch. You may still have to replace the relay 
occasionally, but that should always be cheap and easy.

OTOH, I've never had to do this to any of my cars. (Knock on wood.) 
You're most likely to have trouble if you have to crank the engine a 
lot to get it to start.


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