LAST MONTH I CAUSED a bit of confusion when I said we'll be looking at an area of the car which is often clouded in mystery - electrical gauge senders.
Down at the Chequered Flag, I was constantly hounded by people wanting to know what sort of things I'd be looking at. And if they weren't asking me that, they wanted to know why they should bother to think about things like that. After all, they said, if the fuel gauge or temperature gauge wasn't working, it was a simple job to go out and buy another. Well I can congratulate myself in that I was right in what I thought. Not many people understand how they work; or how to go about checking them without just replacing them.
It was my old mate Herbert that I think I upset the most. He just scowls at me now, and hasn't spoken to me for a few days. I have to admit that it was him that gave me the idea for this topic. He'd been telling me about how he always had a good steady flow of work from people who didn't understand electrics. That's silly, I thought. After all, provided you follow a few basic principles, it's all fairly easy.
I think most people get worried about electrics when they think back to the time when they accidentally got an electric shock from a household appliance. Most of us have done it at some time. It comes as a very sharp reminder that electricity is not to be messed with. And don't listen to the idiots who say things like "Not to worry, car electrics is a doddle! After all, it's only twelve volts!" No matter what the voltage, or the current, electricity is dangerous if handled wrongly. Many's the time that I've had to survey the scene of carnage caused to a car's wiring loom when a short circuit has started to melt wires. I can assure you all that it's not a pretty sight, and it can be jolly expensive to put right. In one very sad case, a beautifully restored MGC Roadster was completely burned from half way up the bonnet to half way down the boot lid. Even the aluminium windscreen frame had started to melt in the fire. That particular problem was caused by connecting a battery charger the wrong way round. Whilst that was obviously a severe example of the sort of problem that can be caused, it is worth remembering that often, the damage caused by faulty electrics is beyond the scope of the D.I.Y. person, which means a trip to the local garage to get it put right. (There, that should put a smile back on Herbert's face!)
But now to wipe that smile off his face, unfortunately. I often think back to the Public Service Information film that used to be broadcast on the B.B.C. many years ago. Mr and Mrs Happy Family and their children were to be seen having breakfast, when the drip, drip, drip of water appeared on the table. Oh no, a burst pipe. The family leapt into action, and in the course of the next frantic minute were seen to be taking all the right actions to stop the leak and prevent further damage. This included incidentally, what to do to make sure the water didn't come into contact with any electric points. Then, after congratulating the family for their correct and prompt response to the emergency, the snooty voiced announcer chastised them "for letting it happen in the first place." Well it's exactly like that with electrics! If you're very careful, work slowly and methodically, there won't be any burnt out wiring looms.
So how exactly do we go about looking after the electrical system on the car? Much as though people will call me for saying this, I'm going to say it again. Be Prepared! (And yes, I was a Cub Scout many years ago. Can't seem to recall just now what it was that made me go along to the meetings. But I do remember we had a lovely Akela!) The preparation for working on electrics covers a few basic areas.
First of all, Tools. Apart from the run of the mill screwdrivers, pliers and so on, it is essential to have a test lamp. It's fairly easy to make one. A bulbholder can be saved from an old wiring loom. Next time you're down the local scrapyard, have a word with the proprietor and cut one from a damaged loom. Some bulbholders only have a single wire going into them, with the "earth" contact being made through the body of the bulbholder. Try and avoid that type, but rather get one with two wires going into it. A sixties era BMC saloon ignition warning lamp does the job a treat! Try and get as long a length of wire as possible. This allows for greater flexibility when using the test lamp. Of course, much better than a simple test lamp is a multimeter. The modern new fangled digital rubbish can be bought quite cheaply now - some for less than ten pounds. But a far better idea is to keep an eye open at the 'jumbles and search out an "AVO" meter. It might cost a few bob more, but it's a lovely piece of equipment. If you've not come across one before, AVO stands for Amps, Volts, Ohms. And yes, I know that my AVO is much bigger that Herbert's new digital meter, but at least I don't put my meter down and lose it, like some people I could mention!
Secondly, Time. Don't be rushed when dealing with electrics. If you haven't got time to do the job properly, don't start it.
Finally, the dreaded wiring diagram. Although they look daunting at first sight, they really are essential to help you understand electrics. And for those of us with the need for a good light, reading glasses and a following wind to read newsprint, there's absolutely no hope with a wiring diagram. So take your workshop manual down to your local High Street copy shop, and get them to blow it up to a larger size. It'll help greatly when it comes to having to use it!
So, now we're ready to look in detail at the ins and outs of electrical gauge senders. We'll do that next month.
'Til then
Safe Driving
Spannerman
Got a technical query for Spannerman? E-mail your problem to the old boy and we'll try sort you out! He might even ask his old pal, Klaxon...after he's sorted out just what IS e-mail!
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