tackling electrical gremlins today

Morning all,    I'm going to be tackling some electrical gremlins today in my 92 Rivage cabriolet before mot that I bought as a non runner and trying to put back on the road.

I thought I'd post on here before I start pulling things apart incase any of the problems are common obvious fixes,   the list is as follows

- Electric roof only works with ignition off
- Rev counter stops when lights are on
- dash illumination goes off when lights are on
- the blue high beam warning light is on and goes off when lights are turned on

I'm guessing the three problems linked to lights are probably all one thing!   I'll add to the list when I find more today!

Thanks
Marc

Morning well I think I can knock this one off your list.
"Electric roof only works with ignition off."

They will only work with the ignition off as it's a built in safety feature. It's to stop drivers from attempting to do it on the move and rip the roof clean off!

The other stuff sounds like bad, dirty connections, relays and stuff but I'll let our electrical guru's deal with those! 👍 😀

Ahhh that does make sense,  although my last one worked whenever so that must have been played with,  I wonder how I can get it to work while running?   If anyone knows?

Got to ask but why would you want to circumnavigate this safety feature? 🤔

Sent from my Smartphone 📱

Golf Cabrio said

Got to ask but why would you want to circumnavigate this safety feature? 🤔

Sent from my Smartphone 📱

Ejection seat installation and doesn't want to replace the   roof, padding and headliner each time.

The electric roof circuits are in the Bentley.  I would imagine you would need a switched power source that picks the relay.  (that is all I am going to say.) I hate working around safety limiters, save for the 91.5 - 93, Automatic won't start….

As for the others.

Inspect all your Headlight and Light circuit fuses.  Shoot, look at every fuse….

The High beam Light is on with key on and the dipper switch isn't pulled?  

Normally:

I would replace the headlight switch first.
I would then be thinking about the ignition switch or the load reduction relay issue (also know as the "X" circuit)

Interesting that the Tach stops when you turn on the headlights.  As they aren't on the same circuit.  But that leads me to believe that you have an open ground wire and the tach dropping when you pull the headlights is a sign that you are taking ground away from it or that it is phantom grounding via the headlights and turning them on is removing the iffy ground path.

So first thing I would do is Validate that when you have the ignition switch on in run.  That pin 2 and pin 14 on the main cluster connection has ground on pin 2 and  Battery B+ on pin 14.

The only thing all the lights, Tach, and the high beam have in common besides the need for battery B+ is ground.  

So lets back up.  Is your Battery to Frame and Frame to engine/transmission cable original, or the ends replaced and the main cable is original?  If so, I would first replace it, with 2 off the shelf cables from your local parts provider.  You can purchase new cables the main battery one with additional take offs so you can get rid of the Ring connectors on your ground (earth).

You will find that the cable goes from the battery to the frame under the airbox, then from the air box over to the transmission mount bracket or a double stud on the Transmission to Engine bolt, usually the upper rear mounting bolt.  

Measure the distance of the enigne to frame and then the frame to the battery to get 2 cables the proper length.

Clean and shine the frame horn stud with a wire brush.
On the Battery Jumper (frame to engine) Smack those suckers flat with a BFH (Big Flipping Hammer) and use 2 fender washers on Both sides of the harness as you bolt it on to the frame.  Spray the connection with Battery Corrosion Paint…

Now after all is done see if you haven't resolved your issue.  

I have seen a Car use Sensor grounds to power things when the major grounds or earths are iffy.  I have seen water temp senders used as starter grounds, Frying the Clocks.  I have seen Clutch and Speedo Cables do it as well.  I have seen o2 sensors being used as grounds and when you start the engine you fry the Digifant Controller.

After that I would look for the Ground connection on pin 2 of the instrument cluster as being iffy, and I have solved a lot of my issues with adding a Ground from pin2 wire side to the frame behind the X on the cluster mount.  

Then I would be looking at the headlight switch…as in Replacing it or a connector wire that is iffy.

(Wouldn't hurt to check it first as well.)

2nd I would be thinking of relaying your headlights.  This will give them total battery voltage and current.  Shortens the electrical run to the headlights from 8 and 10 feet to about 3 feet of wire.  
You off load high current off the headlight switch and increase the life expectancy of your switch by 100 percent.

Here are the links that you need to look at.

Improving Cluster Ground connections.
Improving your Cluster Connections and ground. | Volkswagen Owners Club Forum.

Improving your ground connections on a 90ish Digifant.
Ground effects and the repair of your car. | VW Vortex - Volkswagen Forum

Three relay and 2 relay to improve your headlights.  The 3 relay adds the Low beam filaments to your Headlights when the Hi-beam is selected.  (Brighter hi's)…
Relaying your Head Lights | Volkswagen Owners Club Forum

Just my two Cents.  

Check you have the brown earth wire on the back of the rocker cover, it's an earth and when my wire broke the rev counter would nearly die and blue high beam light came on.

My wire broke in half so I re joined it and fitted a new ring connector on the end.

You can just see the brown wire at the bottom of the picture.

thanks all,  I got as far as fixing a fuel leak and the radio today 
Unfortunately I had no signal where I was so only just seen all this.  (also I've noticed I do not get email notifications when someone comments)

Firstly,  roof question, I'm not silly enough to try and raise / lower the roof while moving (more than snails pace) but I'm sure it will annoy me to have to turn the ignition off fully just to raise or lower the roof, It's not a big deal but if there was a quick easy way around it I would

Briano,  thanks for all the info,  I'll print this and take it with me when I next have a play,     Yes,  blue light on dash with ignition and normal lights on, without the high beam pulled.   Then I pull stalk to turn on full beam and the full beam comes on and the blue dash light goes out, it's back to front!!
I actually done all the engine/battery/frame earths already,

 Mark1gls,   how strange, I haven't checked that but from memory the wire doesn't look great,  I'll sort it next just in case!

Thanks all,  much appreciated
 Rgds Marc

You have a break in the brown earth wire going to the instruments, if it's not the brown wire in the engine bay it's the brown earth wire going to the instruments, tap in the wire near the plug at the instrument end and get a new bit of wire to make a new earth.

I had the same problem as you and after I made a temporary earth to in instruments they worked so I replaced the earth wire in the car and it wa still no better so next I looked at the earth wire in the engine bay and that was broken.

You can just see the brown wire at the bottom of the picture.

1. this is normal, but easy fix. you need to look at your hood wiring near the fusebox for a grey wire which is live only with ignition off. this wire needs cutting/unplugged and swapped to an ignition live feed. it comes from ignition switch pin P which is the parking lights feed, you cant just tap this to ignition live it'll play havoc with the indicators


2-3 sounds like a bad earth to clocks, covered already

alternatively if you start at the ignition switch end look at terminal P. there should be a wire from here to the indicator stalk, leave that be. the other wire from P that disappears in the loom is the trigger for the hood relay.

I'm not 100% how the P wire gets to the hood relay setup, as the bentley isnt clear, and only covers US models. I assume there will be a spade connection on it somewhere for the euro cars, as VW wouldn't hard splice the hood loom to the dash loom, the hood loom should be removable. I actually have a complete uncut hood loom somewhere in stock, but its been years since I last saw it as its buried deep in the pile

I had the exact light problem that was solved today… The brown wire to the instrument cluster looks like someone had tapped into it before to fix the earth.. But had done a poor job..  We cut the fix out and mad sure it was back to original..  all OK now..  It is a pain sometimes to turn your ignition off to let the roof down, I agree(especially if you have an immobiliser) . There is a way round it to disconnect the two connectors in the boot.. Worked on my rivage..  See pics

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wilson    did you try this ?  if your wiring is standard you should be able to lower your roof with the engine running.. this pic is taken in the boot..  disconnect the two spades and you are done

Ahh awesome,  I only just seen this so will hopefully have a look at the weekend,  car passed MOT yesterday the instrument issues were a bad earth and a burnt out diode…  I appreciate all the suggestions and help

 I've screenshot this to have a look at the roof when next dry

Still lots to do, all good fun (sometimes)


 Thanks
Marc

Well that was easy,  simple unplug and the roof works anytime

Awesome,   Thanks