Power Steering gone again

Skipton01

Skipton01

Admin Team
Thought I'd solved it with the extra earth, but the fault returned this morning, together with a faulty oil level/temperature sensor. Fuse 38 is blowing, so there's a power feed fault somewhere and according to the schematics, the same feed goes to both the sensor and the power steering controller (as well as to many other things, most notably the G65 air con pressure sensor).

Not got the time to do anything at present, but will be unplugging the suspect units and putting a fuse wire across to see which is faulty or if the wiring itself is shorting out.

Cheers

Mike
 
i'm sure if you wait a few mins our resident expert will come on with a how to......................oh hang on YOU ARE OUR RESIDENT EXPERT !!! i'm sure you will get to the bottom of it mike. but why do these thing crop up in the freezing cold? hope you get it sorted soon. mikee
 
Think it's sorted:

The trouble with that feed from fuse 38 is that is goes to many, many things - the hazard switch, the climate compressor, the heater controls (on non-climate cars), heated seating, auto-dip rear view mirror, parking sensors and a few others.

Taking the easiest first, I whipped out the Bose amp, which is a retro-fit, to see if any of my wiring was shorting - it wasn't.

Next, on to the oil level/temperature sensor - undertray off job, then crawl to the back of the sump and disconnect the 3-pin connector. No short at the connector and the pins in the sensor are too deep set to check with a meter, so I put a length of fuse wire (no sense in wasting mini fuses at 50p a shot!) into the 38 position and started the car.

To my dismay, there were 2 warning beeps again. On looking at the display though, they were for the sensor (unplugged) and the fuel level - the ramps were tilting the car at sucj an angle that it had decided the tank needed filling!

So, no power steering fault warning (yet - touch wood).

If anyone else gets the stiff steering in future, check out fuse 38 and then go through the components one by one (an easy way to tell if it's blown is to see if the hazard switch is lit - it normally is, regardless of the position of the light switch).

Cheers,

Mike
 
The steering went again last week and no amount of faffing would get it back this time.

I suspected a fault in between the connectors at the lower A pillar and the components, as I had a G65 fault, various earth faults and the steering fault itself, and all this pointed to a loom problem.

Today, I took the bumper and nearside light and wheel off, so that I could check continuity at the power steering connector and this showed that there was a short to earth at both the spwer steering pump and the G65 (which is the high pressure sender in the refrigerant circuit).

As a fault wasnt immediately apparent, I then took the dash out of Tank and followed the loom up to the firewall - no damage apparent.

I then went back into the engine bay and traced the loom back to the bulkhead and was about to get VERY frustrated when I noticed a small amount of chalky substance on my finger when I ran it behind the loom where it runs alongside the nearside suspension strut.

On further investigation, the loom has been constantly rubbing (more like vibrating) on a weld blob and I think that this has finally worn through a positive feed and resulted in a lot of melting and corrosion. As well as 9 wires running to the power steering controller, ambient temperature sensor, fog light and G65, there are the main 2 wires (thick 6mm feed and earth) that carry power to the power steering and as this is controlled by an 80A fuse, you can imagine the amount of current in there!

I'll get photos up tomorrow, but I have been VERY lucky not to have suffered a catastrophic fire and total loss of the whole car.

It's going to be a big job to reconnect the loom, as the wires are corroded right up to the firewall, so soldering in new sections is going to be tricky, but I've got nothing else planned over the next few days! I'll take advantage of the dash being out to tidy up all the rest of the wiring too I think - there's been many a mod installed since it was last out and it's pretty untidy under there!

It may be wise to inspect your own looms for signs of rubbing - this looks to have been a time bomb waiting to go off since Tank left the factory - it's nothing that I have been anywhere near in the course of my mods, so isn't down to me!

Cheers,

Mike
 
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Sounds like you embarked on a big job - and it's a good job too..!

Will look forward to seeing the photos as this sounds like something that may be worth checking out on other A2's

Ian
 
Below is a photo of the problem area:

DSC_1240.jpg


The red arrow points to where the blob of weld is and you can see the blackening on the plate below, where the shorting and melting/fire has been. The yellow arrow points to the loom securing lug and above it, you can see the remains of an earth wire, together with the clipped wires that were melted together.

The coolant header tank has been removed in this photo for ease of access and also to show the area better in the photo.

This is what the inside of Tank looks like at the moment:

DSC_1238.jpg


I've successfully stripped back the affected wiring to the inside of the car (you can just see the loom popping out near the far A pillar trim in the above photo) and soldered and insulated new wiring in place and routed it back to the engine bay.

Tomorrow, the job continues......

Cheers,

Mike
 
I'm pretty certain now that this was the root cause of my power steering faults less than a year into ownership that took Stockport Audi 2 months to resolve (and even then, it returned every so often).

As they undoubtedly moved the loom around in the course of their investigations, the short to earth was probably stopped when the loom was put back, but slowly and surely it has become more and more if a problem as the blob of weld bit deeper into the cable insulation.

I think that I should get the front end of Tank back together tomorrow and then the dash re-installed on Monday, after some neatening of the many, many additional looms I've installed over the years!

Cheers

Mike
 
All fixed!

A bonus is that the oil level sensor has also come back to life - even though it seemed to be a root cause of fuse 38 failing, it seems that it was all caused by the loom failure.

I've just a few trim pieces to refit and the iPod to put back and then it's all systems go again (apart from the 2 bolts left over - I know exactly where they're from and as it's a dash out job to put them back, I'll not bother!).

The steering seems unbelievably light now!

Cheers,

Mike
 
Well done no chance of any warranty recourse?
Mind you doing it yourself you know its been done correctly.
would have been so sad to see this car ablaze.:eek:
 
chubbybrown said:
Well done no chance of any warranty recourse?
Mind you doing it yourself you know its been done correctly.
would have been so sad to see this car ablaze.:eek:
Click to expand...

Tank is long since out of warranty, so no recourse there.

However, as you mention, I know that the job is completely right now, with all new wiring oversized and routed in such a way as to avoid chafing - Stockport Audi had the car for 2 months to sort the same problem out and they never got to the bottom of the matter, blaming fuses and finally, moisture in a connector!

This wiring loom is something I'd urge all owners to check, as all A2s have this particular loom and if the thick wire to the pump motor should go, as opposed to the thin controller wires in my case, then you would almost certainly lose the car in a fire.

I may bring this up with Audi, more from a design perpective than anythin else, as there is also another bad piece of design as the loom passes through the bulkhead.

Cost to fix: £16 for wire and consumables

Time to fix: 14 hours over 4 days

If this was an Audi bill, I'd be looking at around £1200 I suspect!

Cheers,

Mike
 
Skipton01 said:
This wiring loom is something I'd urge all owners to check, as all A2s have this particular loom and if the thick wire to the pump motor should go, as opposed to the thin controller wires in my case, then you would almost certainly lose the car in a fire.

Cheers,

Mike
Click to expand...

What is the history of A2's going on fire, notwithstanding malicious fire raising and road traffic collisions? Anyone got data on this?
 
dan_b said:
Mike how do we all perform this loom check?
Click to expand...

Whip the bonnet off and then get an inspection lamp to the nearside suspension strut mount, as shown in the photo earlier in the thread.

You'll see a large corrugated rubber grommet coming through the bulkhead with a massive loom in it. This loom splits into 2 main parts: 1 goes around the top of the engine bay, under the rubber seal to the front of the engine, the other goes down the side of the strut mount and along the inside of the wheel arch.

With the ignition off, run your fingers along the back of this latter loom and feel for any chafing or any residue, which would be white powder resulting from aluminium corrosion.

If there is any, then it's time to get repairs going before its too late, otherwise, feel for any lumps or weld blobs and protect the loom accordingly.

Cheers,

Mike
 
Hey Mike any good refit would not be complete without screws left over lol. Glad you got it all sorted, will check mine at the weekend so i can get it done in the daylight or wedensday if we get out of work early enough

Cheers Phil
 
Yes, the bolts were from the top of the blower motor - I was going to remove it to get better access to the wiring loom, but after I took the top two bolts out (that hold the motor to the aluminium top strut), the assembly didn't budge and I couldn't be ar5ed getting down and dirty even more, so I left it at that.

The daytime cold up in the Pennines has been pretty bad - I can wrap up and keep my body warm, but my hands were constantly numb and I was getting tired, so forgot to replace them before the dash went on - I then started replacing components from the drivers side first and when I got to the 2 left over screws, I really did not want to rip the whole lot out again, so I'll see how it goes. Any rattles, then it'll have to be seen to, otherwise, I can wait till summer and the lighter nights (not to mention warmer weather!).

Cheers,

Mike
 
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