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Tiger Speedo problem

23 May 2020, 3:34pm
Hi
sorry to bother yall but got a problem with my speedo[confused]
finally been able to get out in m cat e1 and all was well, speedo worked fine then it dropped down to 10 miles an hour when i was going about 50.
its a digital one with a 2 wire magnet speed sensor fitted to the prop.
Im hoping its not the clock thats had it as they look real expensive[eek]
checked wiring to speed sensor and when the magnet is on sensor i get continuity at the speedo plug, was told i should get a/c voltage when wheels spin up is that correct? i did try that with multimeter and got no voltage, not sure if this is right.
Hope someone canpoint me in the right direction
cheers dave
first pic shows car in 4th gear
23 May 2020, 5:48pm
How many magnets are on the prop, check they are all there. I've had them come off !

Also check the gap is correct between the magnet and sensor.
23 May 2020, 7:38pm
it has 1 magnet on the flange, should the gap be around 2mm
cheers
Dave
24 May 2020, 10:09am
Check that the wiring to the speed sensor is intact.

I had a problem with one of those Hall Effect sensors - the wire was touching the exhaust which had melted the insulation.
The speedo needle would not move until I reached about 40 - 50mph at which point it would jump up to the correct speed, then drop to zero if I slowed to below 40.
24 May 2020, 1:18pm
Lucky@LeMans wrote:


Also check the gap is correct between the magnet and sensor.


If the sensor is a reed switch, a magnet gap too close could limit the number of pulses per second, if too far away it may not pick up some pulses.
24 May 2020, 4:16pm
I had loads of problems with these sensors. One failed during an SVA test, the examiner was right arsy about it. The car failed SVA thanks to that single issue ! Then all the hassle rebooking and retesting weeks later !
24 May 2020, 7:55pm
Hi Lucky you were spot on.
I didnt build my kit so i thought it was just 1 magnet on closer inspection i could see where the other magnet should have been,
fitted a new one and it worked.
had the car in bits lol too
thanks again
24 May 2020, 8:59pm
Well spotted , I thought that was most likely !