Strange issue. Speedo not working. Trying to trace wiring - odometer working ok. Rev counter ok. Is it on a cable or a pulse? If pulse any idea on the wiring?
Pulse driven, quite easy to remove the instrument pod and to inspect/trace the wiring… (It won’t be the speed sensor, as the odometer wouldn’t be working either) 1. Unscrew and release the bottom speaker panel by the door/dash on the floor 2. Unplug the wiring harnesses 3. To release the instrument pod there are 2x 10mm nuts to unscrew behind the pod trim piece just above the steering wheel column, you can also unscrew the single 10mm nut in the centre of the trim piece to the pod if it makes it easier for you 4. Then you’ll be able to remove the cluster and check the wiring, dismantle etc. Could be a loose wire/a failed IC in the Speedometer itself (pulse signal converter), if it’s the same as a 1985 Ferrari Mondial Veglia Borletti (which I repaired the tachometer) - SAK 215 is the IC. I can’t remember what mine is for my TR. Photos attached to help you, for when I put a mph speedo dial face instead of kph… Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I agree with Mike. If the odometer is working and speedo needle is not its not the pulse sender. Odds are pretty good if you send out the speedo gauge to be repaired you will be correct. Someone smarter than me might be able to tell you how to trouble shoot the speedo just to make sure.
Thank you all so much. I’m wondering if it’s a cable from or to the odometer that has failed possibly?
Hi Ian. It was the Tach on my previous Mondial... unfortunately not been able to test my TR odometer yet, due to the recent storms+poor weather in the UK and now the leaking radiator.... I plan to put the car back together and do a short test soon, before it goes off for it's major service and radiator repairs. Will keep you guys posted, at least I now have the unicorn IC for the odometer as a final piece to replace after all the other work. Best regards Mike
You might be lucky and yes it could be one of the cable connections.... even just a dirty/dry connection joint on the wiring harness.
It’s a separate odometer down by the digital clock. It’s not integrated into the speedo etc. The connection behind the odometer seems fine, I’m wondering if there is a cable that runs from the odometer white block over to the speedo that has failed etc.
There is indeed a shared/integrated wiring loom, you will see in one of the pictures at the top of the steering column white connector blocks and wires from the column stalk switches... this also partially connects into the wiring loom used by the central console gauges / high beam blue light etc and the odometer. I will take some pictures to further help, as I still haven't mounted back my odometer in my car
Perhaps you could do a continuity check between the odometer and the speedo. A red/black wire carries the signal from the odometer to the speedo. There is a disconnect plug between the odometer and speedo, but I don't know where it is.
kieron, your profile says a 92, but those have the odometer in the instrument, not near the clock. as I know it so you have then a 512 TR and not a testarossa?
No it’s a late registered UK Testarossa. 92 manufactured and registered in 93. A bit of an anomaly I know
ok thank you for clarification I would try to test if you have + and - and signal may be switch the speedometer wires to the rpm meter and test if this will work does someone knows when F changed the odometer from the center console to the instrument?
Looks like the round plug is for the speedo? Image Unavailable, Please Login Check continuity from the plug above to this plug Image Unavailable, Please Login According to the wiring diagrams, there should be two red/black ("RN") wires attached to the same pin on that rectangular plug. Diagram here: https://www.dropbox.com/t/fwBZajEGnzBqprsd
Mike to the rescue again. The fault was in the square connector that you circled. Dirty connection. Cleaned all contacts across all the connections behind those pods (although two were working ok but can’t hurt) and hey presto I have the speedo back working as it was. Thanks to Mike and all the gang here.
Strange. If it was the square connector, the odometer shouldn’t have worked. The signal from the sender to the speedo goes to that connector, but not through it. Anyway, a happy ending.
It could well have been another connector behind there. I decided to pull everything to bits and give everything a long needed clean up. Sorted a rattle near the passenger door too today. Plus a general clean up inside. A productive Sunday afternoon
Great to hear you managed to sort it Kieron and a lovely car. Glad we could all help on the forum Thanks Mike
