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Voltage drop, where to look?
MR930 - March 28th, 2014 at 05:12 AM

My beetle has been getting hard to start. Sometime floods and needs to be left for a while. Yesterday I started looking and I have a voltage drop at the coil, starts fine when I run 12v straight to the coil, so I have an issue in the wiring.
Anyone had similar problems and how did you fix it?
I know I can put a relay in but I'd like to keep it original.

AA003 - March 28th, 2014 at 07:18 AM

Ignition switch.

What year model is it?

MR930 - March 28th, 2014 at 03:37 PM

It's a 74 model, balljoint front, swing axle rear.

Joel - March 28th, 2014 at 05:13 PM

You need to find the other end of the coil wire where it attaches to the fusebox and measure the voltage there to see how it compares to the coil end.

It's a very long wire run and is unfused so many of them get toasted over the years by dead shorts at the choke, cut off solenoid and coil from people hitting mainly the choke terminal with spanners and other tools as it's uninsulated.

If it checks out the same it is most likely the ignition switch as Phil says.
The contacts pitt in them and cause voltage drops.

psimitar - March 29th, 2014 at 07:15 PM

originality doesn't really matter in this instance as the relay can be easily removed for originalities sake but in the mean time the realy will give better starting, esp if you put one in the starter line too.

at the end of the day the ign switch has to pass a heck of a lot of current and is why all modern cars use a switched live relay to power the car. This removes the strain from the switch.

If you cracked the switch open you'd probably see the contacts are eaten away and badly oxidised from the years of arcing as the ign is turned on.

Your choice but the relays is a handy way to make old vehicles more reliable.

hulbyw - March 29th, 2014 at 08:12 PM

Every Beetle deserves a relay in the starter circuit.

MR930 - March 30th, 2014 at 08:03 AM

Thanks guys, i was hoping for a quick fix but I guess I should do it right so I'm wiring in a relay today.

AA003 - March 30th, 2014 at 09:24 AM

Do it right and replace the switch. Relay will only work for a while. Don't be a butcher.

Joel - March 30th, 2014 at 10:43 AM

Unless you can find a NOS German SWF ignition switch (good luck with that) the shitty repros sold now don't last long without a hard start relay.
Crack one open and you will see why.

Fitting a hard start relay is the smart thing to do and as psimitar said it can be done without altering any wiring, theres a diagram in my switch replacement sticky.

psimitar - March 30th, 2014 at 06:02 PM

Quote:
Originally posted by Joel
Unless you can find a NOS German SWF ignition switch (good luck with that) the shitty repros sold now don't last long without a hard start relay.
Crack one open and you will see why.

Fitting a hard start relay is the smart thing to do and as psimitar said it can be done without altering any wiring, theres a diagram in my switch replacement sticky.


And one for the ignition coil and choke. Maximise the available current for the coil :)

And AA003. You should know by now that making a switch carry all the current is a bad solution and the use of relays makes for a much more reliable solution cos unless you want to change the entire loom too then it's pointless chasing voltage drops thro old switches and wiring. Relays remove the strain on the switch and give maximum voltage, and more importantly, current to those higher draw items like starter, coil and wipers :)

matberry - March 30th, 2014 at 07:06 PM

Quote:
Originally posted by Joel
Unless you can find a NOS German SWF ignition switch (good luck with that) the shitty repros sold now don't last long without a hard start relay.
Crack one open and you will see why.

Fitting a hard start relay is the smart thing to do and as psimitar said it can be done without altering any wiring, theres a diagram in my switch replacement sticky.


Yep x3

I used to perservere with avoiding the relay but these days it's definately the way to go to get the load off the poor quality ign. switch.