Flickering Electrics Then Car Won't Start

[Keithb]

Sometimes I get a flickering of lights - Dashboard and headlights. If I stop, turn off and on again it may clear the flickering but sometimes the engine will not turn over although the dashboard lights are on. If I take the key out and re-insert it, maybe needs a few attempts the engine turns over and starts normally.

 

Having read (obviously not enough)that the Relay 20 caused this problem, I dismantled the relay assembly and found that diesel engined cars don't have that relay! But that did clear the problem for a couple of weeks. However, now it's back even more than ever.

 

In another thread Mirez suggest an alternator problem - but as the fault also affects the engine turning over, I wouldn't think the alternator would be the cause. After I jiggled the relays it worked for a couple of weeks so is there a bad connection there - which one to look at. Or is it something else - ignition switch?

 

Any suggestions appreciated.

 

2003 TDI 115BHP Auto

 

Keith

[Mirez]

Alternator problems can present themselves as a flickering or pulsing of the dashboard lights - it's unlikely to be intermittent though and unless your battery isn't being charge then I wouldn't be suspecting it at the moment

 

Its Relay 30 (Sometimes badged 27) you need to be looking for not 20 :angry:

[Keithb]

Thanks Mirez, You're right I should have said relay 30. But that doesn't exist in a diesel engined car, Any suggestions as to the likely relay?

 

Keith

[seatkid]

Thanks Mirez, You're right I should have said relay 30. But that doesn't exist in a diesel engined car, Any suggestions as to the likely relay?

 

Keith

Relay 30 is the fuel pump relay in a petrol engined car!!

 

Flickering lights are usually wiring related or a faulty alternator.

 

Start by checking the main fuse distribution box in the engine compartment - it is common to have a faulty crimp on the heavy cable from the alternator at the fuse box end and this causes it to overheat/start melting and then exhibit all manner of electrical problems. Another problem area is the earth connection from the battery to the bodywork.

 

It could be the alternator brushes are near the end of their life and you're getting occasional loss of voltage regulation when the brushes don't make good contact with the rotor. Not sure, but it should be able to remove the regulator/brushes to check they are not worn out or stuck.

[Keithb]

Thanks Seatkid, but how would a problem with the alternator cause the problem with no turning of the engine after stopping the car?

I have checked all the 'heavy duty' fuses next to the battery - no sign of burning out or melting.

Keith

[Mirez]

Thanks Seatkid, but how would a problem with the alternator cause the problem with no turning of the engine after stopping the car?

I have checked all the 'heavy duty' fuses next to the battery - no sign of burning out or melting.

Keith

 

I really doubt you have an alternator problem with the issues you describe. The fact it got better when you removed the fusebox panel would suggest the fault is in that area, possibly with a relay and/or the wiring around that area - its very hard to diagnose electrical faults over the internet but I would take the unit apart again and remove and clean the contact of the relays and fuses. Are any fault codes being registered?

[seatkid]

Thanks Seatkid, but how would a problem with the alternator cause the problem with no turning of the engine after stopping the car?

I have checked all the 'heavy duty' fuses next to the battery - no sign of burning out or melting.

Keith

 

I really doubt you have an alternator problem with the issues you describe. The fact it got better when you removed the fusebox panel would suggest the fault is in that area, possibly with a relay and/or the wiring around that area - its very hard to diagnose electrical faults over the internet but I would take the unit apart again and remove and clean the contact of the relays and fuses. Are any fault codes being registered?

 

There have been quite a few cases of loose connections on the back of the fuse and relay carriers in the fusebox.

[Keithb]

OK, Relays exposed again and relay 14(engine immobilisation) is prime suspect When I remove that I get the same symptoms as when the car doesn't start - dashboard lights on but no engine turning. Starting ok at the moment so maybe it just needed re-seating. I'll run around with the relays exposed for a while so I can thump them if it re-occurs.

Thanks for the help so far.

 

Keith