Electrical Gremlins All Over

[smudger28]

Hi Guys

Thanks for having me on the forums.

My son has recently bought a MK2 1.8 Scirocco 1986 and it's a cracker. Bodywork and mechanically sound but not 100% electrically sound.

So far we've had:

1. Dash lights not working - If the dimmer was turned up then the main beam led and oil led would come on and the rev counter drop to zero. This was rectified by connecting the rocker cover earth.

2. Right rear indicator and left reverse lights not working: The light cluster connection tracks were cleaned and this solved the issue.

3. The rear lighting was dim. This was solved by cleaning the earth on the boot behind the number plate.

This has left us with:

1. Rear wiper not working, clicking heard from the relay.
2. Head lamp and handbrake switches do not illuminate.
3. Horn not working, no clicking heard from the relay but fuse sound.
4. Internal light only works when switched on. I have found a spade connector off which must be the door live switch. I just need to re-connect that somewhere on the switch.

I'm going to look at the horn at the weekend. The car has done 120k, so I went back through it's MOT history and the horn fails on numerous occasions.
This would be my priority at the moment as the others he can live with.

Has anyone else had any of the above issues?

I will keep posting as I rectify each snag.

Hopefully post some pictures too.

Thanks

Paul and Dawson

[chopperoli]

Can't help with specifics but don't forget basics, check primary charging, battery positive and negative circuits, they are usually deteriorated by now... any corrosion or high resistance in main ground cable especially where it meets chassis and engine can cause all sorts of problems. Plus look at the alternator charging voltage, should around 14-14.5v at the battery

I believe the horn is switched ground, on the steering gear

Does your son have a digital multimeter

[GT_II]

The interior light is earth switched, so all brown wires connect at the switch end. The door switches connect to earth via the fixing screws - check for corrosion to the door switch contacts, screws and fixing points.

[smudger28]

Can't help with specifics but don't forget basics, check primary charging, battery positive and negative circuits, they are usually deteriorated by now... any corrosion or high resistance in main ground cable especially where it meets chassis and engine can cause all sorts of problems. Plus look at the alternator charging voltage, should around 14-14.5v at the battery

I believe the horn is switched ground, on the steering gear

Does your son have a digital multimeter

Hi Chopperoli

The alternator and belt are pretty new, as is the battery. The main earth lead in the engine is a bit shabby and is getting sorted this weekend along with all the engine earths.

I have a multi meter as I'm an aircraft electrician by trade. I'm teaching the boy how to use this things as we go along.

Will check the horn also this weekend.

Thank you for the input.

[smudger28]

The interior light is earth switched, so all brown wires connect at the switch end. The door switches connect to earth via the fixing screws - check for corrosion to the door switch contacts, screws and fixing points.

Hi GT_II

I think the spade brown cable that's flapping in the breeze is possibly the switched earth. I will check tonight when he comes home. Hoping to sort all the lighting issues before the weekend.

Thank you

[smudger28]

Hi again.

So I reconnected the loose brown spade and the light still did not come on. Cleaned the switched earths on the door and the light started working! Sprayed and cleaned them up.

The headlamp switch looks like the bulb has blown as does the handbrake warning light. Do you know where I can get these tiny bulbs from please?

Thank you.

[mark1gls]

It’s common for the headlight switch light to fail as it’s always on when the ignition is on, I’ve replaced 2 in 20 years of ownership and currently it’s blown again but not worried about it.
I went to a local motor factor with my old bulb and they found the right one for me.

The car horn, there’s an earth wire with a spade connector on the steering rack, near the UJ boot and it gets covered in old oil and gunk so a good clean may help.

[GT_II]

The headlamp switch looks like the bulb has blown as does the handbrake warning light. Do you know where I can get these tiny bulbs from please?

https://forum.sciroccoregister.co.uk/vi ... ds#p159902

[smudger28]

Thanks Guys for the replies.

The headlamp bulb is blown, the handbrake one wasn't so I put the good bulb in the headlamp switch and that works a treat!

I will order some more tiny bulbs just in case.

The handbrake warning light has two cables in the back, one green/white the other black. I think I have 12v at the black cable and the green/white is the earth return? I'm not sure I get any earth here at all. Any idea where that light gets its earth from?

@Mark - where is this earth on the steering rack? What's a UJ boot? Do you have any pics. I'm still learning the car.

Many thanks guys

[smudger28]

Oh also I filled the rear washer bottle up with water and that doesn't work. I tested for 12v and earth at the connector when stick pushed forward and both are fine, so I'm assuming the little motor is kaput?

[GT_II]

The handbrake warning light has two cables in the back, one green/white the other black. I think I have 12v at the black cable and the green/white is the earth return? I'm not sure I get any earth here at all. Any idea where that light gets its earth from?

From memory, the handbrake light switch is the same type as the door light switch, under the handbrake lever I think, so you may have the same problem there.

[smudger28]

The handbrake warning light has two cables in the back, one green/white the other black. I think I have 12v at the black cable and the green/white is the earth return? I'm not sure I get any earth here at all. Any idea where that light gets its earth from?

From memory, the handbrake light switch is the same type as the door light switch, under the handbrake lever I think, so you may have the same problem there.

Next job tomorrow then Thanks

[smudger28]

Handbrake light fixed!

The push button switch on the bottom of the handbrake was loose. That's another job out of the way.

I have started another thread for the horn as I think this is the biggest job so far.

Many thanks

Paul and Dawson