Blowing Fuses

[albotek]

Hi,

 

I have a c8 2.2 HDI.

 

I first noticed that the clock was about 20 minutes fast (may be nothing to do with anything). Then I noticed a right hand rear sidelight bulb had blown and its fuse.

 

Replace fuse and bulb and all was well for a day. Fuse went again.

 

I noticed that the screen wash not working. Replace fuse and it blows when screen wash is activated.

 

The rearside light fuse blown again (bulb ok)

 

I notice that the voltage on the fuse is 14.55 volts on tick over.

 

This seems to have started when I helped a friend out with a jump start. (or may coincidental) OR have I damaged the regulator or alternator?

 

Any ideas please before any more serious problems arise?

 

Thanks in anticipation,

 

Dave

[paul.h]

When I have checked battery voltage with an engine running it has been about 14.4 volts so 14.55 does not seem too high - however, does it go up if the engine is revved ? Do the fuses blow if the washer / lights are turned on but without starting the engine - this would help rule out the alternator ?

[albotek]

Thanks for your reply Paul,

 

As soon as it stops raining I'll check the voltage when revving. Tick over is just under 1000 rpm.

 

It does seem that the right side-light fuse blows when the engine is running although it is not immediate. However regarding the screen washer fuse this blew immediately without the engine running so it may be that there is some fault with a screen wash pump. Whether this is due to an over voltage situation is yet to be ascertained.

 

I'll get back to after a voltage at revs check.

 

As of yet (I'll probably wish I hadn't said this) there are no signs of any malfunction with any of the entertainment or computer functions.

 

Dave

[albotek]

Hi again,

 

I have rechecked my initial findings and it seems I may have been led up the garden path by a poor earthing point. If I earth to the aircon pipes I get a higher voltage reading to the fuses but earthing to car chassis the voltages seem to measure within safe parameters.

 

I have now confirmed that the voltage across the battery varies between 14.39 and when revved 14.41 so I would imagine one would consider this normal.

 

I let her tick over for about 10 minutes with the lights on and no fuse blew even when revved. I have, however, now disabled the auto lights feature as on the last two fuse blowing occasions it was this that activated the lights.

 

I have left the screen wash fuse out for now until I can investigate this issue.

 

So, hopefully, the alternator and regulator are ok.

 

Dave

[paul.h]

On our last C3 the screen washer pump fuse would blow if the jets were frozen so maybe there is a blockage in the jets or pipework, or the pump is faulty. On cold days I would try a quick touch on the washer switch and if water did not come out, would leave it until it warmed up - this prevented the fuse blowing.

 

Is the light fuse that is blowing just for the right hand side lights ? If so, I would check that tail light for corrosion, the wiring to it for damage and similarly to the front right side light and the number plate lights if these are also going out. You could also check the old bulbs from that fuse and not yet replaced in case one is faulty and that they are of the correct wattage. If the wiring to the rear lights goes through a hatch door to body rubber sleeve, check the wiring in it in case it is damaged - some cars like the mark 1 C4 are known for problems here. You could also check for good earths in case something is trying to earth through a bulb - you could try with the side lights on and then put the hazards on to see if the side lights dim.

 

The auto lights may just be coincidence - looking at a Haynes wiring diagram for a C5, and if I have read this properly, the light 12 volt supplies are from the battery through relays in the bsi that are switched by the bsi, with the fuses on the light side of the relays. Hence a fault that causes a fuse to blow has to be between the fuse and light bulbs

[albotek]

Thanks for your thoughts Paul.

 

Having forgotten to turn the lights off after my testing I have a flat battery :). Luckily my drive slopes out on to a sloping track so nice and easy to bump. I didn't want to jump it just in case. I took her for a bit of a ride and switch side lights on and off with engine running and on reaching home they were still on.

 

Funny you should mention bulb wattage. The bulb I originally replaced was from a universal kit. It fitted and worked so I assumed all ok until this fuse blowing episode. I'll check that out to be sure that I have the right bulb.

 

The fuse that is blowing is for the right rear side-lights, number plate, front side-lights and aircon panel light (according to the hand-book).

 

I now assume, and hope, that the screen washer problem is a separate issue. I need to find out where the pumps are.

 

Thanks again for your thoughts Paul.

 

Kind regards,

 

Dave

[paul.h]

The washer pump tends to be fastened to the bottom of the washer bottle and in Citroens is often in a front wheel arch needing the arch liner or under shield to be removed to get to it. One pump seems common and it turns in opposite directions for front and back washers.

 

If you need to disconnect the battery, a procedure I have used without causing odd electrical problems is in the C5 Technical section, common problems post.

[albotek]

Thanks a lot Paul.

 

I'll get back to the forum when I have further info.

 

Regards,

 

Dave

[albotek]

UPDATE:

 

 

I turned on the lights manually yesterday while running the car. I dint stop to check at that point but by the time I got home to look, the 10 amp fuse had blown but all bulbs ok.

 

I have just stuck an ammeter across the blown fuse and, with the engine running, I am getting a reading of about 1.97 amps, with the lights on, even when revving.

 

Not any further forward.

 

Dave

[paul.h]

2 amps = 24 watts = five 5 watt bulbs - front and rear side lights and 2 no plate lights + dash which seems correct.

 

Have you got a towbar fitted or any other accessories that may have been taken off this circuit ?

is there any water in any of the lights ?

You may have to look for damaged wiring catching on something.

Maybe you could try disconnecting each light connector in turn and see if this points to anything.

[albotek]

What I'm going to try is to try to connect my meter "permanently" for a few days and monitor what happens when out on a "normal" drive.

 

Intermittent faults hey you gotten luv 'em ...NOT!!!!  :rolleyes:

 

The car is going in to the garage on Thursday for a dreaded INTERMITTENT engine management light (and loss of power of course) so I may ask them to take a loom at the lights too.

 

Thanks Paul.

[albotek]

UPDATE:

 

OK this is getting weird!  :unsure:

 

Because I cant let it go I have been battling to find out what is going on with my C8 and its blowing 10 amp fuse problem.

 

I have discovered, after blowing a shed load of fuses, the this particular fuse blows only when the lights are on and then I turn the engine off. It's at engine switch off and the lights on that the fuse blows. I can restart the engine with the lights on (after replacing the fuse) and all is well.

 

I can turn the lights on and off with engine off or on and all is well. But the second I turn the engine off, with the side-lights on, the fuse blows.

 

OK I'm repeating myself now.

 

So the work around is to remember to switch the lights off before switching the engine off.

 

I cant imagine what could be causing this as no other circuit seems to be affected. (I know the water pump fuse has gone too BUT I'm assuming this to be a separate issue.

 

Very odd  :huh:

 

Dave

[paul.h]

Does the engine shake a bit when switching off - just thinking it may be causing a damaged wire to earth. If the ignition is on but the engine not started, does the fuse blow if it is switched off ?

 

Are there any things not quite right about the dash which may be causing it to draw current through the fuse ? Now you know when the fuse blows you could measure the amps at the fuse with it removed - will give you an idea of the wattage of the culprit.

 

Next thing may be a problem with the bsi. May be a battery disconnection could reset a fault, if any. Try the procedure in the C5 Technical section Common Problems post.

 

It may still be worth checking the earthing of the lights (and maybe some others - dash, bsi) since bad earths can cause unusual problems.

[albotek]

Hi Paul,

 

The engine doesn't shake when switching off, but the thought did cross my mind. I am out of fuses now so I'll get more today and do some more testing.

 

The car did go in for some diagnostics yesterday, because the engine light keeps coming on and I lose power. I asked them to look into the fuse problem too.

 

Unfortunately they were not able to come up with anything with the diagnostics apart from it reported "YES THERE IS A FAULT" but no clear pointers as to where. They did find that the additive tank is completely empty so that may explain the engine light and power loss problem but they say they cant refill it so that is my next course of action.

 

They have no clue, other than we have been discussing, as to what could be causing the fuse issue.

 

I'll keep you posted.

 

Regards and thanks again,

 

Dave

Edited January 31, 2014 by albotek

[albotek]

Update

 

I have been living with this, blowing fuse, fault for a while now. Luckily I havent needed the lights, however, I hate to let things defeat me. I had a couple of mechanics look into it but all shrugged there shoulders and didnt want to get involved. So I thought I'd have another crack today. I put my meter across the fuse holder and monitored the current. It was when I pulled the hand brake up that my meter went into overload protection. I cant see and chaffing or near by electrical cables along the hand brake cable so I am thinking that the fault may be under the brake lever mechanism.

 

Dave

[Gilbern Invader]

I think you are on the home straight, there is a mountain of cables under the handbrake and a dropped coin or something like that could be causing a short. Best to use neat concentrate screenwash all year round because of the daft positioning of the washer jets in the wipers making them vulnerable to freeze because of the wind chill, they did not work in the BX either.