Hello, I've got an intermittent issue with the power steering on my VRS where it will temporarily cut out while turning sharply (such as when parking), the warning light flashes up, I feel it go heavy and then it comes straight back. Additionally it has fully cut out while driving a handful of times, which has meant I've had to turn it off and on again to get it back.

I have taken it to a garage to look at but they couldn't get it to fault and couldn't find an issue without taking things apart and costing me money. They also didn't find any fault codes on the ECU.

I checked the power steering fluid which was low so I topped it up but it didn't solve the issue.

I have also put a new battery in recently so it can't be that.

Any help would be greatly appreciated. 

 

Chris

Have you checked the alternator output?

I haven't, what should it be? 

Surely if it wasn't working my battery would go flat though? 

 

It should be 14.4V while running, if it drops too low the ECU will cut power to the steering and you'll get your symptoms.

Ok thanks, so is there any way to test it? I'd assume it's outputting 14.4V 99% of the time until it randomly drops down and the PAS cuts out but what would cause the voltage to drop?

Don't assume anything at all about the voltage your alternator is outputting, measure it.

 

You can borrow or buy a mutimeter and measure voltage across battery posts before and after starting the engine. Or there are LED-display voltmeters that plug into a lighter socket.  Don't leave that plugged in all the time though, or it will itself discharge the battery slightly when the car's off.  

 

Does your battery symbol light come on when you turn the ignition to the position where lots of warning lights self-test?

 

 

Edited 31 January, 20215 yr by Wino

I have a multimeter so will check voltages tomorrow and see about the battery light. 

 

Someone told me it could be the steering angle sensor, is this plausible? 

One thing at a time.

Oh, and don't rush into buying a new alternator if the battery symbol doesn't appear, there is one particularly common wiring breakage that can cause this and is cheaply fixed.

So I've just checked voltages and I get 12.8V with the engine off and 14.49V with the engine on. The battery light stays on when the other lights disappear as well.

All looking good there.

Does that rule out the alternator then? or could it be intermittent? 

I think the whole charging system is OK, although  you could still have a poor contact somewhere in the power feeds to the steering pump.

Have you inspected the main strip-fuse that feeds the pump, in the fusebox above the battery?

VCDS can tell you the voltage that is actually getting to the pump itself, in real time, which would be handy to know.

 

I've looked at the fuses above the battery and they seem fine. 

How would I get it plugged into VCDS?

Pumps are quite well known for failing, particularly earlier ones in the plastic shroud as the noise deadening foam sucks up and retains water. They probably predate your car.

Easy enough to change. Think the bumper needs to come off and the left hand wheel arch liner.

Related common failure is the steering angle sensor located at the bottom of the steering column, accessed from underneath. Quite expensive to buy new so you'd want to be sure that was the issue from fault codes.

Wouldn't the pump fail completely if it was going to? Rather than doing what mine's doing.  Also, could a steering angle sensor be faulty and not show any fault codes? 

From what it's doing it would seem to be electrical somehow, possibly a dodgy connection somewhere?

1 hour ago, Chris_19 said:

  Also, could a steering angle sensor be faulty and not show any fault codes? 

 

Yes that does happen.

The pump might go intermittent first. It's power hungry and needs a good earth, so also worth cleaning up the main earth point nearby that it connects to, as well as the main battery earthing point on the chassis.