1972nail wrote:Ever had an ignition fault that burnt out your Viva?
I had one such fault back in the '70's but thankfully it only fried the loom. I kept the old loom, here it is.
When it happens it is an instant stopper and your car is dead!
The cause is a resistance wire buried deep within the loom. It's there to provide a reduced voltage supply to the coil when the engine is running. During starting the resistance is bypassed and the coil gets a full 12v. On other makes of cars and earlier HB Vivas a simple ballast resistor is placed at the coil safely out in the open where it can do no harm.
Why bypass the wire?
In my case I want to run an Electronic Ignition system that requires a 12v coil and supply. I also was 'bitten' before by the resistance wire so I want to make my car a bit safer. There are other threads on the forum telling you how to bypass and wire in a ballast resistor, thus retaining the existing resistor type coil.
if you bypass and don't wire in an external resistor you MUST replace the coil with a 12v one. Beware, your cold starting may be sightly impaired.
So why does it burn out?
Well, if there is a short circuit there is no fuse on the circuit so instant overload.
Here's how I bypassed the wire in preparation for fitting Electronic Ignition.
The 'resistance' coil feed runs directly from junction D4 on the bulkhead fuse box - the white wire on the right of the 4 in line.
Just simply swap it to junction D5.
You'll have to pop out the whole red connection from the fuse box and use a small screwdriver to release the 'barb' on the terminal. Reset the barb before pushing the wire back in.
No hacking into the loom required, the resistance wire is still there but it no longer is connected to anything so it can't do any harm.
Happy days - 12v ignition - simple!
Just wanted to say thank you for such a clear guide. I followed this when installing electronic ignition and changing the coil. Thanks!
