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Rear Defogger Design Changes, Series III

Rear Defogger Design Changes, Series III


Evolutionary, the Series II and the Pre-HE XJ-S had heated rear windows that were simply switched on and off. It was a regular occurance for owners to leave the rear screen demisters in the on position just because they forgot it was on, regardless of the indicator being lit. It also accounts for the heated rear window switch to be the one out of the four in the console that had to be replaced first due to the length of time that the load on the switch had to be sustained. I mention this as a precursory note because it is only in the S57 guide (did you notice how I slipped that in Doug, now that I have got one too) that the round relay is mentioned for 'early cars'. But the point is, it is a relay and not a delay unit! As far as the parts catalogue is concerned, the early cars upto 85 were fitted with a delay unit which is at odds with the S57. However, in the later 85 onwards cars there was a variation, which stated that the same delay unit DAC1328 later superseded to DAC10020 was fitted for Canada only and that for everywhere else UKC2421/J was fitted up to VIN 470472 and thereafter the DAC1328 delay unit was fitted. So to summarise, I would have expected Jaguar to have progressed from the original straight switching idea to the fitting of a standard relay in circuit to protect the switch from load. Later on it would be understandable that they fit a delay unit (timed event) to circumvent owners forgetting to switch the demister off. This pattern did indeed happen for the later 85 onwards cars with the Canadians having the benefit of the delay unit throughout.


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