Bright but then dim

Hey can someone help...have an electrical fault with me 90 G reg. When am driving the lights keep going dim both dash and main lights plus the fan slows....temp gauge right up now and again but always sitting high since the prob started plus Some times go so dim that relays stop working to lights and indicators they just buzz....but then it all goes ok for a bit. Mainly goes dim when accelerating or decelerating.

Am thinksing an earth fault but one of that magnitude...ie everything gone to **** would point where? Bat? Alternator? Am at a loss to be honest and cant afford to take it anywhere!

Please help!

Sound like a dodgy alternator. Had similar problem dropped in a new altenator problem fixed. However exspensive option so try everything else first

Not sure alternator would sit the temp gauge high would it???

Sounds like a dodgey earth to me, id have a look round and see if any have come loose and even if not, often corrosion occurs between the earth strap and the body (or thats what happened to me anyway) so its not gonna hurt to disconect a few, clean the mating surfaces and reattach them.

Ollie

no probably not could be seperate problem?

olmasters said:

Sounds like a dodgey earth to me, id have a look round and see if any have come loose and even if not, often corrosion occurs between the earth strap and the body (or thats what happened to me anyway) so its not gonna hurt to disconect a few, clean the mating surfaces and reattach them.

Ollie

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Thanks ollie...where do i look though for a problem that big....ie everything goosing up???? Its not a little earth here or there...must be a biggy!

thetondon said:

no probably not could be seperate problem?

Click to expand...

seems to have all started happening around the same time

I got my hands on some wiring diagrams for my 90 to help me through, i think they might have been from the rave manual but im not sure. Although it cant hurt to go under your landy and double check the major earthing straps.

Ollie

There is a large Earth cable from the side of the engine block (passenger) below the alternator which earths out on the chassis rail just opposite, it often gets corroded on the chassis end. The cable can also internally corrode. There is also a Earth cable running from the gearbox to the chassis rail (same side) unbolt them clean refit/replace and grease. This may be either causing the problem or a contributing factor, nevertheless, its cheap and easey to do, the cables are cheap too.

I had the same problem on me own an it was the main chassis to engine earth. home made strap did the job.

Thanks for the replies. Crawled around underneath and found that the main earth to the engine was green and weakend where it is bolted to the engine mount. Got one from Halfords for a fiver including some cable ties. Also checked the main battery earth but the was fine! Started up and temp reading normal and lights in cab brighter than they every been!

I suppose the dead give away was that the lights dimmed and temp went up when reving the engine hard...almost juddering it...must have been flexing the earth! Happy ending till the next thing!