redlight Posted August 13, 2016 Share Posted August 13, 2016 My 5 year old speedo, electronic, stops working when it gets hot. It is affected by the foot brake, falls to zero, comes back when brake released. It also dances with the indicator. Some improvement with a new earth wire to the ignition lock. The speedo works fine when cool. If if you have had this problem and found a solution please would you let me know. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted August 13, 2016 Share Posted August 13, 2016 ... electronic... Driven from the gearbox or a wheel?Some improvement with a new earth wire to the ignition lock. Have you got the Workshop Notice about this?Jonathan Link to comment Share on other sites More sharing options...
redlight Posted August 13, 2016 Author Share Posted August 13, 2016 No Jonathan I haven't. Could you post it?Rog Link to comment Share on other sites More sharing options...
redlight Posted August 13, 2016 Author Share Posted August 13, 2016 Sorry, the wheel. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted August 13, 2016 Share Posted August 13, 2016 I suggest you send a Private Mail to John Vine.You also need to set the sensor spacing: I haven't got the notes for that either, but it's in the archives.Jonathan Link to comment Share on other sites More sharing options...
Mark w Posted August 13, 2016 Share Posted August 13, 2016 This is almost certainly the sensor .My car used to do this after getting hot on track days . Caterham changed the speedo unit but the problem returned .I finally sorted it by changing the gap on the sensor ( trial and error ) .It seemed to be caused by heat soak from the brakes .Problem hasnt returned . Link to comment Share on other sites More sharing options...
John Vine Posted August 14, 2016 Share Posted August 14, 2016 Post #4 here suggests a couple of causes (air gap and loom interference) plus fixes. Your symptoms suggest a problem with loom interference. If so, WN572 will fix it.(Just seen your PM, Roger. I've sent you WN572.)JV Link to comment Share on other sites More sharing options...
redlight Posted August 17, 2016 Author Share Posted August 17, 2016 Thank you Jonathan and John, the fix seems to have worked. Just been for a 55 mile drive with the heater on and suffered no speedo problems. Heat seems to cause the problem. I did make a couple of changes to the suggested procedure, I drilled a 3.5 hole in the tube and tapped it to 4mm using a bolt to fix the new earth. I also cut the old earth wire leaving a tail on the connector block, this was then soldered to the new earth wire. Once done it was heat shrink wrapped, remember to put this on the wire first. I could not see that the old earth wire could be removed from the connector as suggested in the Workshop Note. The old earth wire was then taped back into the loom. Thank you for your help, it is good to post and get a sensible solution!Roger Ashelford Link to comment Share on other sites More sharing options...
John Vine Posted August 17, 2016 Share Posted August 17, 2016 Good news! Glad it worked.JV Link to comment Share on other sites More sharing options...
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