Power Steering Failure: An awkward theory

Disclaimer: This is a theory, an awkward theory and not to be taken seriously, at least until I can prove it or replicate the symptoms and cure...

I'm not a mechanic. I'm just a curious and creative Citroen C3 owner who felt the effects of the Power Steering failure very often. For the last twelve months I watched the malfunction show itself a few times a week and during the last 30 days, almost daily. As this Forum taught me (thank you gentlemen!), I applied all the tricks in the catalog - 3x key, whole reset, you know what I mean, to get Power Steering back. As I said, during the last month, it got worst. The only way to get Power Steering back was to wait a couple of hours. I never really believed in replacing the Power Steering motor (your stories about that replacement were not very conclusive about the failure fixing...).

So, with a MOT inspection coming my way, I decided to give my C3 a general check for the simple things I can manage myself like oil, filters, brake pads, wipers, etc. I replaced a cracked headlight (and oh boy I was proud) and polished the other one (I could quit the Gymn...).

I had a few blown lamps. Most of them were low cost (chinese), some of the bulbs who were still in working condition but a bit dark, so, in a moment of sheer courage, I replaced them all...

I used Osram bulbs for the whole set. (This maybe weird but you will understand my reasons in a minute).

Went to the MOT inspection, the car passed it in flying colours, and returned home...

The first thing I noticed on the following days was that the Power Steering was completely OK...

As I am not a mechanic, I was puzzled... Could the Power Steering fault be originated by a lamp "poltergeist"? That makes no sense at all, even for a non-mechanic...

Armed with a huge dose of patience, I refitted the old rear lamps (benefits from not cleaning my garage often...). Went for a test drive and the malfunction came back!

My theory started to gain life on that moment. On the first opportunity I installed the new Osram bulbs and the Power Steering was OK...

I know this makes no bl--dy sense, but it's my experience. 15 days have passed since this, and I never saw the problem again...

I suppose there could be a lot of sense that you have just put being that the brains of the car get so many signals, pulses of information i suppose it wouldn't be that far fetched that a simple light blowing could create problems.
As for instance my grandma use to drive a mk4 vw golf 1.9 tdi and every now and then the turbo wouldn't kick in from a certain rev range. vw wanted to replace turbo at £260 so i said id take a look and by chance looked through the car manual and it did state in that that the brake lights would throw up a engine management light. so in turn the turbo wasn't kicking in so couple of quid replaced brake light bulbs and yup you guessed correctly the issue was resolved.

I have also noticed somewhere on here that someone was having a issue with there c3 im not 100% certain but it could of been steering again and they replaced boot bulb and issue disappeared coincidence im not so sure.

And i do know from experience with my wifes c3 the speed sensor which is on back of gearbox causes the same issue only difference is that the speedo goes to zero whilst driving.

MATTHEW LOMAX wrote:And i do know from experience with my wifes c3 the speed sensor which is on back of gearbox causes the same issue only difference is that the speedo goes to zero whilst driving.

This is the only one where I can see why it causes problems. The Electronic Power Steering is variable under computer control depending on the road speed - the same signal for the speedo feeds the EPS (and other things). No or a bad speed signal will upsed the EPS ECU.

It doesn't help that ABS cars pick up their speed signal from the ABS where as non ABS cars pick theirs up from the gear box sensor you mentioned.

pedroaniceto wrote:Disclaimer: This is a theory, an akward theory and not to be taken seriously, at least untill I can prove it or replicate the simptoms and cure...

I know this makes no bloddy sense, but it's my experience. 15 days have passed since this, and I never saw the problem again...

This theory makes more sense than perhaps you realise.

All the circuits in modern cars share many things, power supplies, earthing points and most importantly data connections. Car computers are supposed to be built to endure the harsh environment of vibration, heat and other environmental problems, but the truth is, no amount of testing in the design stage will replicate every eventuality.

Car computers are 'protected' from the outside world by buffer circuits. In theory, each external input has a separate buffer. I say in theory because in reality, one buffer chip has many buffer circuits inside, which are therefore inevitably linked. The failure of one small component inside a chip can effect the way other circuits in the chip work, or even a component within the chip being towards the end of its operating tolerance can have similar effects.

Therefore if anyone ways that there is no way circuit x can have an affect on circuit y, don't believe them. In the words of QI - nobody knows.