AUTO CHECK SYSTEM FAULT POWER STEERING CONCERN

I’ve got a problem with the auto check system fitted to my 1993 Audi 100 2.0 litre. The bulb failure light and the buzzer come on and off intermittently whilst driving. I’ve checked the sidelights and the headlights and all appear to be working correctly.

The warning comes on whether the lights are on or off. When the warning does come up, I can often extinguish it by turning the off and on or on and off, depending on the position at the time the warning sounds.

Have you any idea what may be wrong?

Alan Robins

As the warning light will come on whether the lights are on or off the problem is most likely within the auto check circuits in the ECU. The first point to check is that all connections are good, and a break in the circuit is not occurring due to a poor connection at one of the plugs.

Examine the pins to ensure that they are not heating up due to a poor connection. This is the most likely scenario and when this occurs the problem can be compounded by heat caused from the poor connection exaggerating the problem, resulting in burnt pins.

It would also be a good move to remove each bulb and check there is no corrosion visible at the contacts. Also whilst the bulbs are out, ensure that none of the filaments have broken, allowing the contact to make and break as the bulb heats up. Finally, I would also check the number plate lamp bulbs, as these are often overlooked when checking the side light circuit.

My 1988 Volvo 740GL is used normally one or two days a month but has been maintained regularly. When I first start the engine the power steering is often stiff to turn and feels very heavy. After it has been used for a short while the steering then feels normal until the next time I use it after the car has been standing.

The power steering belt is correctly adjusted, the fluid hasn’t discoloured and there’s no debris in the power steering fluid reservoir. Do you think that the power steering pump seals may be at fault or possibly the seals within the steering rack? If it is the steering pump, is the unit serviceable or will it need replacing.

Michael Andrews

It is of course difficult to be precise without examining the vehicle, but from your description it may be a fault with the pump or with the spool valve at the base of the steering column or it may be fluid leaking past the piston in the rack.

It may also be down to air entering the system when the car is standing and needs to be bled out before the system returns to normal.

In the first instance I would check the fluid and ensure there are no damp patches on any of the connections or hoses in the power steering system that may indicate a small leak where air may be entering.

I would also check the steering column universal joint to ensure it’s not this that’s sticking when left standing and then freeing off after a short amount of use.

Because you confirm that the fluid is clean in colour I doubt if the pump seals are failing, as if this was the case the fluid should take on a darker colour.

The other check would be to jack up the vehicle and disconnect the steering to enable the joints and swivels to be checked. It is possible that the stiffness could be caused by one of these sticking whilst standing.