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Automobile Electrical System


Unfortunately the above picture doesn't really reflect the changes which have taken place in the vehicle electrical system in previous years. In this case, it's not about the changes in plugs or in the cable harness and of course, also not the CAN-Bus technology. The following article is about the number of fuses and relays and their placement.


Nowadays there are fuses in a flip-top box on top of the battery. One should have come upon this idea earlier, indeed, in the event of a short circuit, the plus-wires leading from the fuse-box were always a fire-risk. At that time the water-proofing against dampness was not as effective as it is today. Perhaps the intention was, to save the customer the job of opening the bonnet, as previously, this was the sign of a more serious defect. Also the batteries were- and are still not, always as easy to reach as seen in the above figure.

The wiring to the starter (on the far left) is probably the only one that is not fused, thus demanding the increased attention of the mechanic. It is also fairly unlikely that particularly the screwed fuses with their large cross-sections, should have to be changed, because mostly, they are followed by smaller ones which serve other circuits.
Previously there was a large box in the vehicle interior or easily accessible under the bonnet, it contained all the replaceable components, controllers and also fuses. In the first group, only the working current relay has remained. Modern engines, electrical system-control devices and busses have taken over the work of the pre-glowing time, the indicators and other relays. Therefore, only the working current relays are still needed, indeed, a great deal of them. These are therefore combined on a space-saving circuit board and physically separated from the fuses. Firstly, because it is easier to find a place for two small ones and secondly, because the manufacturers are of the opinion the driver should go no further than the fuse box. In their search for suitable places to insert the fuse box, some developers have struck on the idea that the side of the dashboard is still free, even though one can only reach the box if the door is open. At least then, the crawling around in the leg-room-space, to work on the fuses, has been put to an end. 05/10               Top of page               Index
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Translator: Don Leslie - Email:

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