Power steering intermittent fault and warning beeps

[paul2129]

Hi guys, this problem is on a 2008 Roomster, but I understand it's Fabia mechanicals. Car has 88,000 miles, a 1.9tdi, and a long standing steering fault. I've checked elsewhere on the forum and net, but feel that the specifics of this case might help someone point me to the cause, I'll just list the facts, if you can help, please reply

Fault has got worse over about 4 years

Intermittent PAS loss, often slow speed manoeuvring, comes back on always

PAS warning light sometimes accompanied by Airbag light

Warning light sometimes accompanied by three dashboard beeps

Problem got slowly worse, now goes off during driving (half mile or so)

Lights go 'a bit dimmer' heater fan slows up 'a bit' during slow manoeuvring steering

Car has never had a new battery

Car has never had a new alternator

Battery terminal wire found loose recently, this was not the cause

Fault code "intermittent/sporadic PAS implausible signal"

Also "intermittent/sporadic" engine fault, brake fault, air con fault (no symptoms)

Problem is 'caused' by steering, only when turning does it fail

Mechanic suggests that his electrician can't find the fault until the fault is a permenant failure, but electrician thinks it needs the full PAS module. Is there a sensor in the wheel, or connection in the wheel which houses also the airbag connection ? (Airbag light comes on sometime) is there a sensor connected to the wheel which give direction to the PAS module, could this be faulty, giving the improper "inplausable signal" ?

Edited 29 November, 2016 by paul2129

[xman]

Battery volts too low causing pas to drop out and beeps. Should be logged on diagnostics, scan it.

New battery me thinks.

[paul2129]

That wasn't shown in the list of faults..... but that would be an ideal solution ! Thanks for the comment

[KenONeill]

That's my thought too; has anyone done a "deep load" test on the battery? Incidentally, low revs and high steering angle is the time the battery load is highest, rather than when the starter is running.

[paul2129]

I suggested this morning to the mechanic that it could be the battery, he said that this would have been shown up as a fault code....... however, whilst hardly an accurate method of testing, I have a USB power outlet plugged into the cig socket, it shows the power as it increases when the engine starts, it takes a good 10 seconds to reach a proper voltage (the car starts fine however) but even when the voltage is all the way up, the fault persists (the guage can be seen to be heading down when the steering is turned at standstill. Doesn't this stuff run from the alternator when the engine is running ? or I guess the alternator is supporting the battery, to take electrics work ?

 

I'll get him to test it anyway

[Breezy_Pete]

Quite normal for it rise slowly after start-up. What numbers are you seeing for voltage on your usb thingy? 

[paul2129]

To be honest, there's no scale as such on the USB power supply thing, and I wouldn't trust it, I just think it seems to increase slower than I'm used to. Maybe that's just winter.. however, I've had this problem get worse slowly for probably at the very least 4 years, mechanic says there should be a code set for the low voltage, there's nothing.

We can have a look at the battery and alternator. I do notice the light go more dim, heater fan slows up, bit of a tricky one. Our (very honest) mechanic seems to be fairly confident it's the PAS module, and is getting a price. Don't fancy the big bill..... with the chance that it's not the actual problem

[Breezy_Pete]

Get a multimeter/voltmeter on the battery, take readings before and after starting engine (ten seconds after, or whenever it reaches a maximum).  Then add one or two cabin electrical loads like rear screen heater and headlights, take another voltage reading.

 

It looks to me like your battery is in a low state of charge. Could be that it's not getting charged properly due to e.g. a poor connection in the charging circuit (e.g. earth wire body-to-starter motor, or body-to-battery), or it might be that you have a parasitic drain that is discharging the battery all the time.

 

Does the battery light in the cluster come on when you switch on the ignition? It should.

Edited 30 November, 2016 by Wino

[delta925]

First your battery is on borrowed time so replacement is (over) due.

 

Look at the existing one not just the generic code for physical size but capacity and CCA rating then fit something the same or better.

Don't waste your time and money with a cheap one. Price up a Varta or Bosch 4 year or 5 year guarantee version on eBay. If you are near a TPS who will serve retail customers when I went in a while ago the batteries looked a fair price but I didn't establish the detail. Quantum are a budget battery probably inferior to the original.

 

If this makes a different e.g. PAS fault occurs less often the problem is likely to be supply related. Not easy in modern cars but try and trace the wiring and connections. It could just be a poor contact / terminal.

[paul2129]

The battery has been on charge for several days, took of charge and then tried driving the car, the steering problem is still there. There are no warning lights on the dash, and there aren't any codes generated on the scanner. Also, bear in mind that this probl,e has been around (in a lesser form) for several years, I think it points toward a fault with so,etching other than the battery ?

[Breezy_Pete]

...Does the battery light in the cluster come on when you switch on the ignition? It should.

See this post if the question doesn't make sense to you:

http://www.briskoda.net/forums/topic/401778-battery-light-and-associated-problems/

[paul2129]

Sorry, not been on the forum for a while. The battery light comes on as you would expect, it goes off when the engine starts. I don't think is battery related. I'm finding that this problem is noticed MUCH more in very cold weather. This morning it was 2c, and the car didn't want to manoeuvre on the drive. Triple beeps from the dash, steering light with corresponding temporary loss of power steering and the airbag light flashing on and off ? Does this help anyone diagnose further ?

Also : where do I find the correct part number for the power steering pump/unit on this 2008 Roomster 1.9tdi ?

Is it 6R0423156C by any chance ?

Thanks

[xman]

Jeez

Buy yourself a new battery, or borrow one if you are really mean.

Battery light on the dash just indicates the alternator is working, nothing else. You have a usb thingy that tells you absolutely nothing. Buy a multimeter instead, they cost from about a fiver. You could then see the battery voltage dip when you try a steering manouver, the steering pump takes a lot of amps when asked to steer. If your battery is weak, probably a duff cell at that age, and the voltage dips a lot (the lights go dimmer is a clue), the ecu goes "oh dear", switches off the pump and bleeps at you to tell something quite important has been disabled.

And no, charging the battery for days wont help a duff/failing battery, in fact it will make it worse as that duff cell will be cooking on your prolonged charge.

Start with the simple and cheap options first. Garages are notorious for knowing **** about electrical things. No a failing battery doesnt always put a fault code up and yes they are at their weakest in cold weather especially as your glowplugs are pulling 60+ amps for 10 seconds after that cold morning start.

Oh, and your airbag controller is also complaining about those voltage dips......

What Wino said that its normal for the voltage to rise slowly is not true. Within a couple of seconds of starting your battery should be sitting steadily at 14.3 volts or very close, with no electrical load. With a large electrical load, you may have to rev you engine to around 1500rpm to see the 14.3 volts.

There are several ways to test a battery, and no way is guaranteed to tell you the battery is definitely ok. Dont ask me, spend a few days googling it yourself. All battery testing requires specialist equipment (not a usb doodah)

Or just ignore the advice given in this thread and go start changing steering pumps at several hundred pounds a pop and dont complain if it doesnt fix your problem.

Edited 18 December, 2016 by xman

[paul2129]

Thank you very much for your response, I have a multimeter, so will check the battery today, what should I be expecting, i.e. Rough voltages that would be good and bad during steering operation on the spot ?

Will test and get back to you

I've no problem with getting a new battery, it has to be on its last legs

[xman]

I've no problem with getting a new battery, it has to be on its last legs

Hope you have breakdown cover. Almost 9 years on original battery is not bad. Cost of breakdown cover, stress and lost time, emergency purchase of a battery while stranded roadside, well thats your choice...

[paul2129]

I have breakdown, and you're right, but I have 6 vehicles, I can't put a new battery on all of them 'just in case'

I see your point, and will look carefully at the battery since it might be an easy solution

[Breezy_Pete]

Thank you very much for your response, I have a multimeter, so will check the battery today, what should I be expecting, i.e. Rough voltages that would be good and bad during steering operation on the spot ?

Will test and get back to you

I've no problem with getting a new battery, it has to be on its last legs

 

I can look at that for you in a bit, as I have a permanently wired in digital voltmeter which I can video while waggling the steering.

Edited 18 December, 2016 by Wino

[paul2129]

Thanks very much, that would be very useful :)

[Breezy_Pete]

It'll be a while before I can upload any video, but as I thought, it's somewhere in the region of 5 seconds before the alternator ramps up to full output (which is 14.6V when cold), and waggling my steering doesn't dip it much below about 13.6V or thereabouts.
That's my petrol 2003 Polo, with no other electrics switched on.

 

 

Edit:  Start-up voltage video

Stationary steering-waggle video.

 

The voltmeter is wired directly across the battery terminals, and was reading 12.58V or something like that before opening the car.

Edited 18 December, 2016 by Wino

[xman]

Just for information:

most cheap digital multimeters have an update rate of 1Hz (once per second) and take 3 - 5 samples to respond to a step change. i.e. the majority of that 5 seconds may just be the meter responding. Digital multimeters will not be able to record a short dip in voltage with any accuracy unless they have a special function for this (which is rarely seen).

A good battery fully charged will show 12.6 - 12.8 volts when rested (i.e. engine off after 30+ minutes) depending on temperature. Batteries showing less than 12.0 volts at rest are either deeply discharged or knackered.

However voltage measurements at rest are no indication of a batteries ability to respond to load changes.

[Breezy_Pete]

I think if you watch my steering waggle vid you'll see/hear that the response to the steering waggles appears virtually instantly on the meter.

It's not a cheap voltmeter. Sample rate 2.5 per second according to the datasheet.

Edited 18 December, 2016 by Wino

[rum4mo]

And that is the reason that I bought a cheap moving coil meter a few months ago, it's only taken me about 40 years to get round to doing that - very handy and very cheap for checking for quickish volts/current changes without the need to drag out a scope.

 

Edit:- and probably the reason why better DMMs have a bar representation of what is happening, better than nothing but not as good as a moving coil meter or a scope.

Edited 18 December, 2016 by rum4mo

[xman]

I think if you watch my steering waggle vid you'll see/hear that the response to the steering waggles appears virtually instantly on the meter. 

It's not a cheap voltmeter.

On your start video, the voltage shows 14.55 within 3 samples of the engine running (1.5 seconds in your case) No dvm using dual slope integration (which most are) can catch a voltage dip accuractely unless it lasts more than 2 samples (1 sec in your case). Just because numbers are flickering you cant attach great accuracy to anything displayed but a steady reading.

Trust me,( I'm not a doctor ;) ) but I've been designing things like this for a living for over 40 years.

14.55 volts sounds a bit high for a 2003 polo without stop/start. Have you checked the calibration against a reference? Most alternator regulators are set to 14.30 with a close tolerance.

[Breezy_Pete]

For interest..voltage regulators in alternators are a lot cleverer than they used to be. At start-up they can gradually increase the slip ring current so that the engine doesn't immediately get the full electrical load (and thus doesn't offer mechanical load on the engine as it starts up). It can also respond to step changes in electrical load with delayed/ramped up/down responses to reduce torque spikes.

 

Example ref:http://www.hella.com/startersalternators/assets/media/a04_ti_en_electronics_multi_function_regulators1.pdf

Edited 18 December, 2016 by Wino

[Breezy_Pete]

On your start video, the voltage shows 14.55 within 3 samples of the engine running (1.5 seconds in your case) No dvm using dual slope integration (which most are) can catch a voltage dip accuractely unless it lasts more than 2 samples (1 sec in your case). Just because numbers are flickering you cant attach great accuracy to anything displayed but a steady reading.

Trust me,( I'm not a doctor ;) ) but I've been designing things like this for a living for over 40 years.

14.55 volts sounds a bit high for a 2003 polo without stop/start. Have you checked the calibration against a reference? Most alternator regulators are set to 14.30 with a close tolerance.

 

Yes, the 2mm sockets on the front of the box are to calibrate/cross reference against proper calibrated meters, I did when I installed it, no adjustment was required.  At operating temperature the battery voltage is typically around 14.3V. 

 

I don't quite follow your 'can't catch a voltage dip accurately' logic, 'cos you'll note that a sub-10V reading which I would expect to be very short-lived as the inrush current to the stalled starter motor occurs.  Something similar is caught every time.  Just telling it like I see it.  For the OP to compare against.  Remember why we're here.

Edited 18 December, 2016 by Wino