hi.

got a 1.9tdi octavia with an electrical fault.

driving home this morning and the abs light came on unexpectedly. then the airbag warning light. then the headlights dimmed. then the dash lights dimmed. then the vent fan stopped. then the wipers went really slow......so i switched off everything electrical and got home ok. i stopped the engine and tried restarting it - battery was dead.

left it a few hours and tried again - car started first time. checked voltage at battery when running - 10.5v quickly dropping to 7.5v (and the warning lights were back on by this time).

checked the terminal block strapped to the top of the battery - the left hand cable was loose and had melted its terminal.

i made up a new link and this seemed to work ok - the battery voltage when running rose to 12.6v and was increasing. there were no warning lights on the dash. but the cable attached to my new link was really really hot after just a few minutes running the engine.

i tried running the engine with this cable disconnected, the battery warning light comes on straightaway. testing the suspect cable end with the engine running showed there was only 1.6v between it and the battery -ve.

so, do you think i have a faulty alternator?

or maybe another loose connection somewhere else?

can anyone tell me where this cable terminates? (it's the black one connected to the left hand end of the block).

thanks in advance for your help.

You have a bad connection between the alternator and the battery. The alternator must be connected to the battery for it to charge. It will not do so if it isn't. Connect a voltmeter between the main terminal on the alternator and battery positive. Start the engine and you should be reading no more than 0.5volts. You are measuring the voltage difference between the alternator and the battery. There should be very little difference, so the higher the voltage reading the worse the connection between the two. This method is called 'Volt-Drop' and is the best way to check circuits under load.

Place a piece of heavy cable directly between the alternator terminal and battery positive. Now check your charge rate again. If it's normal then you have just confirmed a bad connection......

thanks railroad,

i will try that tonight.

Hi

change the wire between the alternator and the battery, it comes as a separate part, do it fairly soon as if you keep going it will knacker the alternator, i think from memory the wire was about £30 - £40

well, i checked the cable as railroad detailed above, and there's definitely a fault with it.

i have made up a temp lead with parts from a scrap motor, until i get replacements.

acw was right on the money - skoda just quoted me £36.16 for a replacement wiring assembly.

the connector block on top of the battery is all burnt out where the cable went loose. i was going to replace the whole unit, but it's expensive (£43.82). anyone know where i can get one second hand?

or is it possible to buy just the fuse links?

thanks again for your help, much appreciated.

Exactly the same happened to me (including that it was the left-most wire on the block) : see my comments on http://www.briskoda....tor-or-dfm-wire .

It is with DM Motors of Belfast right now, where they say the wire is still heating up when the engine runs and claim this is a "mystery that could take a long time to solve".

Did they think of replacing the wire??? They will not discuss it with me.

They know I have delayed the Irish Sea ferry booking 'till Wednesday to give time to fix this - I guess they want to go right up to the deadline and then charge me £££££ for the job. Thing is, I cannot get my car back off them until they are satisfied it is drivable.

Nightmare!

If I don't get the car back tomorrow it's rather a lot of money down the drain (oh and I have an MOT booked on on Thursday - in Aberdeen).