Astravan 02 reg - fan running on & draining power

Obviously just a fitter. A proper technician would measure the current the fan is taking rather than speculate.

If the power assistance to the steering is provided by electricity, a good start would be to measure the voltage drop between the battery and the pump or whatever. Poor connections are the usual cause of a lack of power with anything electrical.

Don't think it will be electric PAS at that age? Plus the OP mentions the PAS pump has been changed. I'm struggling to see any relationship between the two.

If the (presumably coolant) fan was drawing so much current that the whole electrical system is being affected, it would blow its fuse.

The running on after switch off may not be a fault; some cars are designed to do that.

I suggest the services of an auto-electrician are likely to provide the most cost-effective solution.

Chris

My Pug 308 had an electrically powered PAS pump.

David

Jolly good; it's not a 10 year old Vauxhall though.

Chris

Electrically driven PS pumps have been around for a while. And changing it wouldn't help if there is a connector etc fault elsewhere in the feed. Hence my saying to check for voltage drop.

But I've no idea if this van uses an electric pump.

It does. Agree 100% that a check for voltage drop in the feed to it is the first step.

What I can't accept is that somehow excessive current drawn by the cooling fan is so high that it's reducing the voltage available to the PAS pump. It might share a common earth point which is high resistance however.

As you suggest, a connection fault to the pump is the most likely cause.

If the OP isn't able to carry out a test for voltage drop at the pump terminals, it might be worth rigging a temporary (fused) feed direct from the battery to see if that overcomes the problem.

Chris

No one should even think of doing electrical work on a car without owning a DVM. Cheap as chips these days, for a basic one.

I wouldn't do that, it may not be just a 12v dc feed. It might be controlled by a variable supply from an ECU.

David

Something that takes as much load as this will not be directly controlled from the ECU. It will have a power feed and *possibly* a control signal from the ECU. So it would be the power feed (and ground) that needs checking.

Googling this shows the system is fairly complex, and frequently troublesome.

There are at least two different systems on petrol variants, and a totally different one on diesels. They all have a relay built in to the pump, and connections to both the ECU and the alternator. The alternator signal stops the pump when the engine is not running. As the OP says that the charge warning light sometimes comes on, that may well point to the general area of the fault.

In view of the complexity, I don't believe this is likely to be fixable either by a DIYer, or a local garage. Either a main dealer, an independent VX specialist, or an auto electrician are likely to be the best bet at fixing this.

Chris

I'm not so sure about that. It will also have a feedback system for the controller too, which may be just reading the fluid pressure...

On our BMW 118i, the electric steering does away with a belt driven pump to "save" around / up to 600 watts of power. I would be surprised if up to 600 watts could not be delivered from an ECU. More than 20 years ago, I worked on equipment with "soft start" where thyristors were passing hundreds of amps.

The idea of an electrically driven PAS pump is that it is "on demand". The assistance varies with road speed *and* rate of turn of the steering column. This determines the assistance required / delivered.

I agree that electrical connectors are commonly items that create bad continuity, especially earth points.

Everything is getting vastly over complex now, the crank / cam sensors on our other car actually convert the pulses to a square wave within the sensor before returning the signal to the specific ECU.

David

Have a look at any ECU. They have small current connectors - not ones which can handle 50 amps or so. Nor would it make sense to run high current wiring all the way to the ECU then back to the pump. And that's before you make arrangements to keep such a high current device cool.

The normal way is to have the high current bit local to the unit, and send a control signal from the ECU.

I agree with a lot of your post above.

There is the possibility that there might be an ECU on the back of the pump.

I do not remember what the wiring on the Pug 308 PAS pump was like. I also do not remember seeing any cables capable of carrying up to 50 amps either, but then it would not be for long as a mark space ratio where full assistance would be required. For instance, if the steering column is not turning, zero assistance is delivered.

OP, when was the coolant last changed / flushed ?

This time of year, the cooling fan should not run very often unless the engine is left running with the vehicle stationary for long periods, other than for A/C of course.

David

[...]

?

Do you mean a connection to the ECU? If so, there is.

The fuse for the power steering is only rated at 10A, so no very heavy currents are involved.

And even when running, it's hard to see how it might affect the PAS.

Best guess is the alternator (I know it's been replaced) or the wiring associated with it.

Chris

No, I mean that some components ( electric PAS pumps, electric water pumps, electric camshaft timing actuators, EGR valves, fuel pumps etc, etc) may have their own ECUs built in enabling local feedback analysis. The fuel pumps on our cars are not just 12v on or off, but have a variable supply according to the data fed to their controller via the CAN-bus from the calculated load on the engine.

The OP said that he thought that the cooling fan was drawing too much current. So, if there was a fault condition in that circuit and a bad connection in the PAS circuit, this might cause the resultant "nought effectiveness" (from the wise fitter) on the PAS and the flickering charge warning lamp.

One has to wonder if the car has been diagnosed at a Vauxhall dealer.

David

[...]

Well, maybe. The fan would need to draw a huge amount of current to do that; surely it would blow its fuse long before then?

Seems doubtful, but for intermittent faults it's tricky anyway.

Chris

&, IME, the Vauxhaul dealer will be the most expensive & least likely to solve it.

Quite true, technicians are university graduates. Rog

Not necessarily. Just possessing skill. For some reason, even basic electrical theory seems to be omitted from 'mechanic' training.