Brake Light Fuse Blows

That must be the roller micro switch that attaches to the pedals.   I saw that kit.

Have you tried drawing it out on paper?  I find that works to check the circuit out when one see ones logic on CAD. Cardboard  

@Michael McKelvey

I'm totally unfamiliar with the Samba kit, but it's just a switch, so here goes:

I suspect the cruise control wiring.  Why?  Because stepping on the brake signals the cruise control to drop out of Hyper-Drive back to normal driving.  Something is mis-wired and shorting that to ground when the brake switch is engaged.

We know it's either the brake switch or the wiring after the switch, because the fuse doesn't blow until the brake switch is engaged.  Either the short is after the switch (light side) or internal to the switch.  Re-look at where you spliced in to see if anything is hitting ground.  If all that looks good, then:

Steps:

Disconnect the light side wire at the switch and step on the brake.  If nothing happens, then;

If you have an ohmmeter, check the light wire to see if there is some resistance ( maybe 5,000 ohms (I'm guessing here).  It should not show a dead short.  If it does, find the short between that point and the lights out back.  If the cruise relay connects to that wire/terminal then disconnect the relay and try the ohmmeter again.  Something after the switch is mis-wired and shorted to ground.

If it looks OK and shows some resistance, you could try using a long jumper wire between the battery or fuse panel (any 12 volts, really) and the brake light wire (remove it from the switch, first) to see if that makes them light.  

If that works, then it's probably in the switch.  Try using the ohmmeter from either switch contact (remove wires, first) to ground and step on the brake.  If either side shorts to ground it's a defective switch.  If neither shorts to ground, move your ohmmeter leads, one to each switch contact, step on the brake and see if it makes normal contact (switch closes).

Lastly, re-connect the wire from the fuse to one side of the switch, leave the light side disconnected and step on the brake to see if that blows the fuse.

I'm still betting on that cruise relay as the culprit, though....

@Gordon Nichols, thank you very much for your lengthy reply.  I will try these things after the garage warms up.  I have two 1500 watt heaters and I have to run them for about 3 hours to warm the garage above 60 degrees.

I have replaced the switch so I don't think it is the problem. The seller of the kit graciously sent me a replacement.

I made all the connections at the master cylinder. I passed the wires from the switch through the hole for the brake line to the master cylinder. I thought there might be a short there but I don't think so.

Here is a link to the kit: https://www.thesamba.com/vw/cl...etail.php?id=2140061

Pedal cruise cancel switch or I have also seen a bad bulb pop a fuse... start with two fresh bulbs an see what happens

@Alan Merklin, thanks for your reply. I have LEDs, not bulbs.

Right now my cruise transmitter is disconnected from the main cruise box. I don't know how that could be related but I am going to finish getting that connected.

i just love electrical gremlins..

@Michael McKelvey  Yeah that is the kit that I was going to buy for the brake circuit but in the end I drove the relay cut off circuit from my 3rd eye wiring on my IM.

For the clutch, I made my own micro switch bracket for the clutch arm on the tranny using the same concept and a relay and my cruise works like a charm.  

This has been a very frustrating few days.

First I spent about 4 hours getting one nut on the back of the ignition switch where I had limited access.

Then, I moved from that to the blowing fuse.

I discovered that the wires from the switch were getting pinched between the switch bracket and the pedal cluster.

It is difficult to avoid that because the wires come off the switch pointing down about 1/8" above the cluster.

Good news that you were able to solve it.

Did you ever get the cruise control going in your car Michael?

I am hoping that moving the wireless transmitter from the engine compartment to behind the dash makes it work.  I also don't know if the speed sensor I am using will work. I may have to replace it with the magnets.

I won't be trying it until spring.

Just run the wire, and stop fighting it. Radio waves don't seem to work too well around old VW engines.

I did run the wire for the wireless transmitter relocation. I may yet have to install a wired switch.

When pulling the wires I had my first experience with wire pulling lube.