Car almost went on fire

[niall campbell]

Ok popped the bonnet to have a routine check & noticed that my Jump Lead + terminal had melted and the bonnet insulation had a hole in it due to touching the plastic cover.


So as I have previously posted, it felt as if my battery was flat, bought new battery to replace 9 year old one; fitted that but problem still exists.

My alternator is off the car to be replaced tomorrow as the codes I have are 02272 , 02273 and 02276 all saying ||Static current stage 1 to 5-tbd as Passive/Sporadic under Systems/Control Unit /drivetrain/ 61 Battery Regulator


So engine ticking over I was getting 14.27 volts at alternator, 14.14 at Jump Start terminal and 14.02 at battery. A loss of 0.25 volts.

Anyway wire stays cool on tickover with no load.

Noticing that wire goes very hot under full load, I switched on the Air Con first and the wire went very hot at the Jump Start terminal. It was cool at alternator and at the battery.

So switched off Air Con and just switched of heater fan full blast.

Exact same thing for Jump Start terminal.

Now I didn't try anything else, but during my play about to find out what was happening, I noticed that a Relay or Relays gave several clicks behind speedo direction but settled down really quick.

Wire behind Jump Start terminal was warm at terminal, but cooler towards bulkhead. Mind you theres only a few inches to really feel any difference.

So, is the + Jump Start terminal just needing changed, as its resistance in here, or is the car shorting between alternator and Jump Start terminal, is the heater fan for the cabin away ?

I haven't checked the earth straps for the car ......................... however the battery one is good, so is - Earth at Jump Start Point.

Thoughts ???

Is it to do with the Voltage Regulator on the alternator ?

[niall campbell]

Battery this morning was 12.6 volts before starting and went to 14.02 v on tickover with no load

[Flash2]

I've come across a similar problem on an A4. Car had a couple of alternators from another garage but was still having charging problems. Done some volts drop tests and found high resistance on the main battery post under the scuttle trim. Like yours, it was getting very hot under full load. I just removed all the cables from the post, cleaned everything and gave if a light coat of grease. Refitted all the cables and rechecked the volts drop. It's been OK since, about 9 or 10 months now.

Jim.

[niall campbell]

Does the post split ? I take it that it joins the engine bay to the bulkhead wiring loom ?

[Flash2]

It was just an M8 stud that had the main battery cable coming from the battery in the boot and all the main supply cables for the engine bay. You remove the 13mm nut and then lift off all the cables.

[dan2485]

Check the cable for the discolouration and stiffness as this can cause a resistance which will create heat.

If found then you need to replace the cable.

[niall campbell]

Yeah was in Audi today and £100 for part number 4F2 971 349 E which is the alternator and starter wire all the way up to the jumper post.

I am getting the jumper post cleaned see what happens.

Anyway taking off wipers and access to scuttle showed it was full of water, so found the draining hole and washed all the rubbish out, there is one small earth wire in there.

And when I took the cover off for the connecting block, which the wire from the jump start leads to; is all cold to touch.

So for me at this stage, leads to the Jumping post as the culprit............................. I took off the bottom engine cover off and it was too dark to check the starter wiring, and follow the wire round the back of engine, under an engine mount, the Cat & up the back of the air filter housing.

[Peter D]

There are two drain holes not one. One under the battery and one directly under the brake servo. Regards Peter

[niall campbell]

Firstly the battery is in the boot, and the drain hole I found was slightly nearside of centre.

The brake servo is on the offside in this car, with no drain hole below it

[Peter D]

Sorry, I assumed it was an A6 and you were talking about the plenum chamber. You need to post up your year and model. Regards Peter