Technical Power steering

[Adymarsh123]

I have had a new alternator, new serpentine belt, timing belt and starter motor and a battery. Since I've had new alternator sometimes when I start the car the battery light stays on and there's no power steering, yet if I turn it off and back on again it's fine? I've had the new alternator checked and mechanic said it's fine, then the starter motor went so that was replaced, and it still did it so put me battery and still it does it. Mechanic said he's cleaned all connections and put a new earth lead on the battery, it worked for like a day, but it's back to doing it again probably like 2-4, times a day. Does anyone have any ideas what could be causing it???

 

[Zardo]

The electrical power steering needs at least 12.0 Volts or it will switch off as a precaution. Therefore looks like sometimes the unit doesn’t "see" 12 Volts. With the engine running, the voltage is much higher, like 13 Volts or above (depends on the battery and the RPM) and the power steering should always be available.

So either the power steering suffers from an unstable voltage or it is defective.

Check: wiring, voltage, battery pole connection (clean it, put special electrical pole grease on them,make sure they’re tight)

 

[the green vanper]

With the engine running, the voltage is much higher, like 13 Volts or above

The charging battery voltage with the running alternator should be around 14,4 V.

I'd also check the main body to engine / gearbox earth strap. Do you hear any strange noises when the battery light is on?

Attached some eLearn docs that might be helpful to understand the system. And check the connections.

 

[Adymarsh123]

The charging battery voltage with the running alternator should be around 14,4 V.

I'd also check the main body to engine / gearbox earth strap. Do you hear any strange noises when the battery light is on?

Attached some eLearn docs that might be helpful to understand the system. And check the connections.

Thanks for your advice. It has had a brand new battery too last week, and my mechanic said he put a new earth wire to the battery is that the same as the earth strap? I'm not very good with cars. I will however try everything you've advised. Cheers

 

[Zardo]

The charging battery voltage with the running alternator should be around 14,4 V.

Not really, as it depends on RPM and load.

Connect a voltmeter to the battery terminals.

Deactivate all the consumers.

Start the engine and let it reach 2000 rpm

Check that the voltage is between 14.2 and 14.8 V (at 20°C)

Measure the current and check that it is around 3 A ±10% (at 20°C)

Check whether the figures are very high or whether there is overloading (excessive escape of electrolyte), whether the voltage regulator is defective or whether the alternator field coil is short circuited to earth

Check the alternator charge with the consumers activated.

Activate the dipped headlights

Activate the heated rear windscreen

Activate the passenger compartment heater fan at maximum speed

Start the engine and let it reach 2000 rpm

Check that the voltage is between 13 and 14 V (at 20°C)

Measure the current and check that it is around 36 A ±20% (at 20°C)

 

[the green vanper]

Hmm, can't quote

14,4V can be considered being around 14,2 and 14,8V.


It is quite obvious that with a so low power system when you

the system voltage will drop significantly.

I agree that I should have been more precise here

saying that this should be with switched off consumers.

However I assumed that no one will be checking if the charging is correct with switched on consumers

 

[the green vanper]

OK, I can now, strange

brand new battery

Might still be not fully charged.

the same as the earth strap

There are several earth straps in the car. Battery to body, body to engine / gearbox are the two main ones that can have impact on the charging. The list and where they are located in a Grande Punto is available in one of the documents I've attached to the previous post.