garryc Posted July 26, 2021 Share Posted July 26, 2021 Got to the stage of the rebuild that I am wiring in the instruments on my S3 Lightweight (12v). All gauges work apart from water temp. When I short the sender out by earthing the connection direct, I would have expected the gauge to swing up to full temp (top of the red) but there's nothing. I used a test lamp so there is a feed from the gauge to the sender unit and then to earth. But the needle stays resolutely at the bottom of the gauge. Any ideas or thoughts to help would be much appreciated. Thank you Quote Link to comment Share on other sites More sharing options...
simonb Posted July 27, 2021 Share Posted July 27, 2021 (edited) Your fault finding process is all correct. Sounds like the winding inside the temp gauge has broken. What happens if you earth the non supply side of the gauge? Replacements are available but not cheap. The temp section can be removed from the main dial and you should be able to undo the nuts holding the terminals to the body and remove the "can" to see inside. Nothing to loose and you might see a break in the wire inside at the terminals. If the break is in the coil itself then it probably is a new/used one as a replacement. Edited July 27, 2021 by simonb Quote Link to comment Share on other sites More sharing options...
steve b Posted July 27, 2021 Share Posted July 27, 2021 Have you tested for stabilised voltage on the live side ? Are the two wires on the correct way round ? The fuel gauge works ok ? Steve Quote Link to comment Share on other sites More sharing options...
garryc Posted July 29, 2021 Author Share Posted July 29, 2021 On 7/27/2021 at 7:18 PM, steve b said: Have you tested for stabilised voltage on the live side ? Are the two wires on the correct way round ? The fuel gauge works ok ? Steve I’ll go have a look. Thank you Quote Link to comment Share on other sites More sharing options...
Cornish Rattler Posted August 4, 2021 Share Posted August 4, 2021 Have you used thread tape by any chance as it can cause the sender not to work or give faulty readings, just a thought 🙂 Quote Link to comment Share on other sites More sharing options...
garryc Posted August 20, 2021 Author Share Posted August 20, 2021 Thank you for all the advice. In the end I bought the brass bleed plug, drilled a 14mm hole and tapped it to 5/8 unf so a standard series sensor would fit. Works perfect. Thank you Quote Link to comment Share on other sites More sharing options...
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