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MG MGF Technical - Electical Fault

Hi Folks,

Any electrical Guru's out there.
Bruce, Dieter or anyone can you help??????

My wife's Honda Civic has developed a fault (Rover 400 in disguise). When you depress the Brake pedal the side lights come on at the front, rear brake and cluster lights come on, dash illumination comes on, clock and radio illumination dims for night use. Similar symptoms as to turning the steering column light switch to dipped but without doing so.

I guess a short somewhere, could it be a faulty switch behind the pedal as it is the release of this as the pedal moves down that causes the symptoms or could it be a problem elsewhere. All suggestions welcome and any ideas on fault finding/ellimination.

Thanks Chris
Chris Catchpole

Me again,

In addition, when I switch the lights on using the steering column switch the rear brake lights come on as well, dash illumination is normal with clock and radio dim.
Chris

I know some old Ford Escorts/Sieras D to G reg (ish) used to suffer similar problems when indicating and braking. I belive in this instance it's down to a poor earth, I think on the rear tail-light assembly. Perhaps something similar is going on here?

Anyway, are you sure it's a Honda? Only I thought they were supposed to be bullet proof when it comes to problems? =-D And I don't suppose any Honda dealer will know what to do with a problem as a result! <g>
Paul Lathwell

Hmmm, definately sounds like a short somewhere, perhaps the steering column switch is faulty? =-s
Paul Lathwell

Thanks for the quick response Paul, It is a genuine Honda had it 6 years from new and you are right apart from tyres, brake pads and exhausts it has been bullet proof.

I have swapped brake pedal switches and that isn't the problem, MGF and Civic parts are quite interchangeable you know, washer jets are exactly the same too.

I will now move onto your suggestion and try the earth on the rear tail light assembly and then the Steering column switch, oh what fun, still the sun is shining so it could be worse.....

Hang on that is worse I should be out in the MGF with the roof off ...bugger.
chris

Ok,

Ive isolated the steering column switch and problem still exists so it must be wiring and I suspect a short or bad earth related to the brakes or lights, where are the rear lights earthed the only wiring I can find goes straight into the bulb holders and they are made of plastic.

The sun is still shining, I bet you are all out with the tops down whilst i,m working.... double bugger

chris

Hi Chris,

Scenario #1
Sounds to me like a bad earth on one or both of your brake lights. When you apply the brakes a supply runs through the brake light bulb and should then go to earth. If there is no earth path then the current will flow back through the side light bulb (the one next to the brake light) and flow to earth through the other side lights and also other bits and pieces which come on when the side lights are on. You should find that one rear side light will be glowing brightest and the others much dimmer. If the side light and brake light are contained in one bulb then this may be difficult to spot.
Suggest you try running a wire from the earth of the brake light/ rear light cluster back to a good point on the chassis. Just open up the cluster and touch a wire to the metal of the bracket and connect the other wire to the chassis. Try a wheel nut or somewhere convenient.

Scenario #2
If the brake light and side light are contained in one bulb then there may be a short inside the bulb between the side and brake light supply. Try removing the bulbs in turn and check. Press brake and if all is working correctly, except of course for the bulb removed, then that's your faulty bulb. This fault happens quite often in these type of bulbs.

PS Did you fit the warning light module to your MGF yet?

HTH

Bruce
Bruce Caldwell

Bruce,

You are a diamond, Scenario 2 was the problem, I cant believe I have been working on this all morning and it has turned out to be a fault inside a 60p bulb.

It all makes sense now I replaced the bulb two weeks ago and obviously the new one was faulty, I've just put another in and the fault is cured.

Thanks for saving the day.

I fitted the warning light module last year, your instructions were extremely easy to follow and I did not have any problems at all. The fuel warning comes on when there is about 1/4 of a tank left and I can't seem to adjust it any lower but I am extremely happy and really appreciate the work you did for me.

Thanks again Bruce, the sun is still shining but now I'm off to the football, Boro v Villa, so the MGF will have to wait til tomorrow to get its roof off.

Best regards

Chris
chris

No probs, just happy to help.

So I can expect a big kiss from your missus then.....!

:¬)

cheers

Bruce
Bruce Caldwell

Bruce,

The Boro beat Villa so you can have two big kisses from the better half.

Cheers
Chris
chris

Will claim them when I meet her!!

and glad to hear the unit is working OK.

cheers

Bruce
Bruce Caldwell

This thread was discussed on 06/04/2002

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