Technical Power Steering

[Brighton]

Hi all,

I've got a problem with the power steering on my 2007 1.1 active Panda and wondered if I could pick your brains.

With the headlights on, the power steering works perfectly. As soon as the headlights are turned off the steering warning light comes on and the power steering instantly stops working.

I had a problem with the power steering a couple of years ago which was fixed with a new battery, but I've not got a clue what could be causing this. It feels like the wrong way round to what it should be.

Has anyone got any ideas what could be causing the problem?

 

[koalar]

Hi all,

I've got a problem with the power steering on my 2007 1.1 active Panda and wondered if I could pick your brains.

With the headlights on, the power steering works perfectly. As soon as the headlights are turned off the steering warning light comes on and the power steering instantly stops working.

I had a problem with the power steering a couple of years ago which was fixed with a new battery, but I've not got a clue what could be causing this. It feels like the wrong way round to what it should be.

Has anyone got any ideas what could be causing the problem?

The motor is finding a new path to earth via the headlights

On top of the battery terminal there are a few extra cables, one of these is the EPS motor earth. It’s not using that one and using the one on the chassis leg instead

Here is the cables that need unbolting and cleaning (green scouring pads are good for this) then tightening back down. Not necessary but a smear of petroleum will mean you will never have to do it again

right hand side on this photo

 

[Brighton]

Thank you for the advice and for taking the time to reply.

I tried this today, and unfortunately it has not solved the problem. There was a little bit of muck there but none of the wires were too bad. Whilst I was there I also cleaned up the other end of the earth cable where it connects to the car under the battery, but that didn't help either (I have no idea if it would, I have no mechanical expertise whatsoever!).

 

[jrkitching]

With the headlights on, the power steering works perfectly. As soon as the headlights are turned off the steering warning light comes on and the power steering instantly stops working.

This is stirring a distant memory.

In the old days when alternators and voltage regulators were much simpler than today, switching a car's headlights on would often switch the alternator into a higher output mode. Now I've no idea how the Panda is configured, but I'm thinking this is pointing to either a failing alternator or a failing battery.

I know the OP has changed the battery two years ago, but that's where I'd look next. I'd start by putting the battery on charge overnight; if that restores power steering functionality, even if only briefly, then replace it.

@koalar, do you have anything that can track the transient battery voltage as you turn the headlights on & off with the engine running? It might be useful to see what a car in good order would usually do.

 

[koalar]

This is stirring a distant memory.

In the old days when alternators and voltage regulators were much simpler than today, switching a car's headlights on would often switch the alternator into a higher output mode. Now I've no idea how the Panda is configured, but I'm thinking this is pointing to either a failing alternator or a failing battery.

I know the OP has changed the battery two years ago, but that's where I'd look next. I'd start by putting the battery on charge overnight; if that restores power steering functionality, even if only briefly, then replace it.

@koalar, do you have anything that can track the transient battery voltage as you turn the headlights on & off with the engine running? It might be useful to see what a car in good order would usually do.

Output of the alternator is controlled via the body computer and the D+ terminal

I am surprised my original answer didn’t fix the problem. It’s a known issue and fits the symptoms

Like when the rear light cluster earths burn out and the brake lights only work when the rear wiper is on

Can be tricky to get clean

If it happens every time you could try a jump lead from the battery negative to the engine and test

 

[koalar]

The other end of the cable does not go under the battery and onto the gearbox

The power steering motor has a separate lead on top of the battery


It needs unbolting and scraping clean. Visually clean isn’t necessary electrically conductive it only needs a dull surface oxide

It one of these two wires that has high resistance. Or the fuse in the box next to the battery

 

[DaveMcT]

It would be wise to check the system voltage from a non ignition controlled source. A cheap voltmeter temporarily wired direct to the battery will give you enough information. Tells us the volts before engine start, during start and while driving. This should be enough to know if its a failing alternator or failing battery. If you can get under the car look up at the alternator. It is low down behind engine driver's side. If the casing is cracked (not unusual), you will need a new alternator. Even if it is still charging a cracked casing is terminal (ha ha) and it will stop working and/or seize solid soon enough.