Speedometer troubles

Speedometer troubles

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Discussion

TVRNick

Original Poster:

15 posts

101 months

Tuesday 20th July 2021
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I've been having trouble with the speedo on my V8S for a number of years -- only working when it's warm
DGS bench tested the transducer and pronounced it working Verdict was "lazy speedo head"

Anyway, now it has stopped working altogether-- not a flicker. Any ideas where can buy a replacement or get it fixed

(I guess it could be the transducer if it was tested in a heated workshop? or faulty wiring? )

v8s4me

7,264 posts

226 months

Tuesday 20th July 2021
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I had exactly the same problem which dragged on for a few years. In the end it turned out to be a frayed wire shorting out. The wires from the speedo run up the side of the gearbox and enter the car through the tub where the cut-out for the gear lever is. Where the wires run over the top of the gearbox they rubbed through the insulation and caused the problem. Eventually the speedo will stop working altogether and the engine will cut out when you slow down eg coming up to traffic lights because the ECU needs a signal from the speedo to keep the ignition firing. The heat was just a coincidence.

You'll need to get the car up on a ramp or stands to get at the cable. Horrible job!

bicycleRepairMan

41 posts

60 months

Wednesday 21st July 2021
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Not sure if this is exactly the same fault that you're seeing, but...

My V8S speedo was playing up - it was worse in the damp, ok once warm, and worse when I loaded the electrics. The speedo would jump up and down by 10mph when I indicated, it would lose 10mph if i turned on my headlights etc. I went up the M3 in the rain at 70mph, but the speedo was only reading 20mph! Turns out, I was losing a few volts across an old relay in the passenger foot well... With the engine off and the lights on, I had 13V at the battery but only 10V at the dash.


TVRNick

Original Poster:

15 posts

101 months

Thursday 29th July 2021
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thanks for the advice - it does point to a wiring issue. I now need get at the back of the speedo It is possible to remove the crash pad above the dashboard to gain access?

v8s4me

7,264 posts

226 months

Thursday 29th July 2021
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Yes but........
Search all the threads on here about removing the dash and then let us know which bit you need help with.
Having done both jobs I'd suggest getting under the car and checking the wiring from the sender first because, believe it or not, it's easier!

"crash pad" - skull splitter might be more accurate laugh

v8s4me

7,264 posts

226 months

Friday 30th July 2021
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This is what caused my speedo problems.....