Speedo and odometer failed

[taylormj4]

Hi Folks,
First the odometer stopped working. That seemed to be that it was just stuck as every now and then (especially if went over a bump) it would start working again.
However, now the speedo has also stopped working.

Do you think the two failures are linked, i.e. is there something that can fail that would cause the odometer to stop but not the speedo?

Speedometer failure causes:
Failed speed sensor at the diff or wiring
Poor connections to the speedo
Any others?

Thanks.

[ianstaffordshire]

My spedo has failed I have found a GPS sender on eBay for about forty quid when I get around to it I'm going to fit one I will put the link on here might be a fix for your problem or not.

https://ebay.us/m/e57Bo8

[sixor8]

Presuming you have the mechanical odometer display, it is a fairly common failure for the odometer to stop working. And the spares are no longer available (ie the small motor inside) to fix them.

The speedometer usually carries on working, it receives pulses, and this may be down to the speed sensor at the rear. It's mounted on the chassis pointing at the driveshaft as it exits the diff on the right hand side. I see you have a 450 so this should be the case. There is only a few thou gap so if you cannot adjust it closer, it may have failed.

[pmc_3]

ianstaffordshire said:

My spedo has failed I have found a GPS sender on eBay for about forty quid when I get around to it I'm going to fit one I will put the link on here might be a fix for your problem or not.

https://ebay.us/m/e57Bo8

I've done this and it works a treat. I wired it in place of the TVR calibration box of tricks. From the plug that went to that box I was able to pick up a live, ground and the signal to the speedo from that plug. There is also a signal to the ECU on that plug but I haven't got that to work yet, I got no reading when I tried but I haven't had any stalling issues at junctions with it disconnected. I've since found I had some faults with my ECU and have replaced it, so am going to try it again at some point and see if it now works. This is the one I went for https://www.ebay.co.uk/itm/334330280076

Edited by pmc_3 on Sunday 19th October 16:15

[taylormj4]

sixor8 said:

Presuming you have the mechanical odometer display, it is a fairly common failure for the odometer to stop working. And the spares are no longer available (ie the small motor inside) to fix them.

The speedometer usually carries on working, it receives pulses, and this may be down to the speed sensor at the rear. It's mounted on the chassis pointing at the driveshaft as it exits the diff on the right hand side. I see you have a 450 so this should be the case. There is only a few thou gap so if you cannot adjust it closer, it may have failed.

Hey Sixor,
Yes still the original mechanical unit and yes to the sender. I've checked and adjusted the gap on it before as the speedo used to not kick in until around 10mph. Got a slight improvement at the time. Any way of testing the senders that you know of?

[taylormj4]

pmc_3 said:

I've done this and it works a treat. I wired it in place of the TVR calibration box of tricks. From the plug that went to that box I was able to pick up a live, ground and the signal to the speedo from that plug. There is also a signal to the ECU on that plug but I haven't got that to work yet, I got no reading when I tried but I haven't had any stalling issues at junctions with it disconnected. I've since found I had some faults with my ECU and have replaced it, so am going to try it again at some point and see if it now works. This is the one I went for https://www.ebay.co.uk/itm/334330280076

Edited by pmc_3 on Sunday 19th October 16:15

Do you have to adjust the unit to give the right output signal for the TVR gauge?