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Help! No spark with cluster on.

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Hi,

I've installed an automatic antenna to my Golf mk1 Cabriolet 1988, carburettor.

The antenna has 3 wires (one black, one red, one green). First i've attached the red wire to the battery +; the black to ground and with the help of a multimeter, I found a wire which would get 12v when I turned the radio on. This worked great and the antenna would rise when I turned the radio on. However after a couple of times the radio went dead. I think I've fried it or maybe it was just bad luck at the bad time.

After the radio got fried I decided to change the antenna green to another "signal". I then got a wire that would get 12v when the ignition was on and installed a on/off switch in the middle so I could make the antenna rise with the key on or have it go down when ignition on and press the button.

I assembled everything, installed the cluster and all the switches and went to turn the car on. Nothing. The car would crank, I hear the starter and the fuel pump working but nothing else did. The cluster had the usual lights on. Everything seemed great but simply the car would not start.

I then removed a ignition spark and tried to see if I've had sparks. Nothing. Tried the same connecting the ignition coil directly to a ignition spark and nothing.

I then removed the plug with the green/red-black plug from the ignition coil and installed only the green wire on the ignition coil. The car started right away!

I installed the cluster and the car started right away when only the green wire is attached to the - on ignition coil.

Now, If i install the plug with the green/red-black wire correctly on the ignition coil without the cluster, the car will start without a problem. But if I install the cluster, I will not have a spark.


I think the problem may be related with the red-black wire that comes from the ignition coil and is also present on the pin position 5 of the cluster plug. It's the same wire that is present in both "devices" so that must be a clue. I just don't know what to do with it. I have no idea why is this happening.

I don't think is antenna related as the connection is pretty straight forward and i'm sure i've done it correctly.

Could this be a problem on the mylar of the cluster which has, like the radio, gone bad at the wrong time?

Can this be fuse related? I've checked them all with multimeter and they were fine.

I can't drive a car without cluster so I need help to understand what might have happened.

I also have another cluster to test the car with but can't do it right now and would also understand why is this happening so I don't burn the new cluster or something.

Any ways or tests I could do to chase this down would be great.  

Sorry for the long wall of text and for my english.

Thanks in advance!

Last edit: by mpercheiro

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First thing I would suspect is always the last thing you did.

Most radios after market have a designated power antenna wire on them.

Your after market antenna or the wiring to them is probably where your issue is.  I would take out the antenna or electrically neuter it and get the wires back to original.  reinstall the cluster and see if the car works as desired.

Most antennas have 3 wires one for +12Switched, One for ground usually black or green depends on the manufacturer and how they have it laid out, if you would mention the make and model of the antenna then we can try to look up the wiring specs.

The cluster uses the input from the coil for the Fuel pump relay as well as the TACH.  so if'n you spliced in to that (thats a big NO NO).

I would check all your fuses, and restore everything prior to you installing the antenna.  

It is always the last improvement you made that breaks the camel back, and lets face it a signal that turns on and off the coil and fuel pump isn't rated to power an antenna as well, so check your fuses with a meter.

Get back to us with the model and make of the antenna.
And I hope you installed a drip stop loop on the co-ax to prevent water from getting it to your fuse panel.

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yeah first check is where you tapped the antenna, usually you would put this to the radio amp output, or you can use an ignition live. for a post-82 ce1 fusebox this is dead simple, just use G spade 1,2,3 or 5.
https://clubgti.com/forums/index.php?threads/fusebox-faq.219775/

does the cluster rev counter jiggle while cranking? you can try popping the tach pin 5 out of the cluster plug to test if it is indeed the rev counter wire stopping the car, but then again if it was that then the fuel relay wouldnt work either. unless its somehow weakening the signal enough to stop the coil triggering a spark.

check the coil wiring is the right way round as well, you should have both blacks on the live side, also labelled '15' the red/blacks go to negative side labelled '1'

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Hi Briano,

Thanks for your answer. The antenna is a Beru (don't know the specific model) and is brand new. The antenna is working. Like I wrote, it has three wires and I'm sure i've connected them well as per antennna instructions.

Red wire -> battery + terminal

Black wire -> ground (I used a door screw inside the fender and under the wheel lining where the antenna is located. I scrapped the paint and made sure there was continuity with the multimeter)

Green wire -> I got that from a permanent 12v wire that goes to the radio plug and added a on/off switch.

I never touched on the red/black wire or made any connection to it. The antenna works as intended when I press the on/off switch.

The car works when there is only the green wire on the ignition coil, or when there are both wires in ignition coil but the cluster is disconnected.

The only thing I did on the cluster plug was to reinforce the ground as per a tutorial seen in here. I took a wire from the ground on the plug and added it to the car chassis. But this was months prior to the antenna install.

I've also checked the fuses visually and with a multimeter, but i'll re-check them. What specific fuse should I look into?! Also, the relays, should I take a look at that?

EDIT: also, the car is currently without radio unit which has gone to repair.

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How my Diz iz connected

Screen Shot 2021-06-25 at 8.02.50 AM.png

Did you plump the main cluster connector as in placing a single piece of electrical tape under the main connector on the plastic tongue under the mylar?

Screen Shot 2021-06-25 at 8.05.33 AM.png

The Radios depening on if they are oem, usually have a
Switched power source main power, and a battery live to keep the clock and presets.  If you picked the wrong wire, then you might have blown the fuse for the Radio.


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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Good morning again!

Just solved the problem. Replaced the cluster and everything was working, including the headlights warning lamp which jad an odd behaviour since I bought the car.

This mylar thing is really a pita. There were some dudes who made a hard pcb for the vanagon. There should be someone doing it for our Golfs.

Anyway, it's all solved! Thank you all for your replies.  

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Glad you posted the resolution.

What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?
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