Speedo and Rev counter inop

TheLordJohn · Apr 6, 2014

Hello all.

All my auxillary belts are in position and working fine, my fuel gauge and temperature gauge both work fine but my speedo and rev counter are both inoperative.
Can anyone point me in the right direction where to start looking?
Is there a common problem area?

Thanks, Stuart.

stopover · Apr 6, 2014

There should be a wire to the alternator for the Rev Counter. If a new alternater fitted it might not have the tach out?
Speedo, do you have mechancal or electrical? The wiring is from the speed transducer that drives from the transfer gearbox if I remember, check plug and then using a volt meter (long wire into cab) you can see if its pulsing when driving, also check fuses. Or the drive if its mechanical going round (take off to the back of the instrument panel)

TheLordJohn · Apr 6, 2014

Cheers mate.

I'd assumed it would be a common fault to cause both to fail rather than two seperate faults. Where are the fuses please?
I'll see if I can see anything obvious on the alternator.

Thanks, Stuart.

stopover · Apr 6, 2014

Would help if you could say what classic you have, year, petrol, diesel etc etc

You should check out the Speed Transducer for the speedo. Its mounted on the left hand side of the chassis v.near the rear engine mount. Ther should be two sections of the speedo cable connected to it, one at each end. Check they are connected and the wiring plug. A bad transducer can affect idle speed.

Fuses!! don't you have a drivers hand book? on later models, in the car, next to heater and ventilation controls just to the left. I don't remember any fused that affect the speedo but its always a good idear to check all fuses. Very Very Very early cars had a fuse box on the engine bulkhead

TheLordJohn · Apr 7, 2014

It's a 1989 Vogue SE, 3.9 EFI.
I'll check those things next weekend, thanks very much.

Oldfogey · Apr 7, 2014

The '89 should be the 2-part mechanical cable, with the transducer in the middle. Probably not relevant, but when mine reached 99,999 miles the speedo stopped working - the speedo itself had jammed attempting to turn that last digit for the first time. I was right up in the north of Scotland and had to drive 500 miles guessing my speed from the rev counter, with the speedo cable disconnected to stop the horrible noise.

So remove the cover from the binnacle, unscrew the drive cable from the speedo, and get somebody to watch the cable as you drive. if the cable end turns, the speedo is dead, if it doesn't the cable is dead.

Thinking back, I don't remember a transducer in my '89 cable, I think it was a single piece... but it was a while ago.

TheLordJohn · Apr 7, 2014

Thanks for the advice - i'll give it a whirl in the next couple of weeks.

stopover · Apr 7, 2014

TheLordJohn said:
Thanks for the advice - i'll give it a whirl in the next couple of weeks.

We await your command MyLord

TheLordJohn · Apr 8, 2014

Lol. Well I would like to do it sooner, but I am in Scotland this weekend coming, so that pushes it back to the following weekend

I shouldn't really have bought his classic as it requires/required A LOT more work than I thought and have time for, but I felt sorry for the thing.

And it sounds the business!!

cartoonhead · Apr 17, 2014

Oldfogey said:
The '89 should be the 2-part mechanical cable, with the transducer in the middle. Probably not relevant, but when mine reached 99,999 miles the speedo stopped working - the speedo itself had jammed attempting to turn that last digit for the first time. I was right up in the north of Scotland and had to drive 500 miles guessing my speed from the rev counter, with the speedo cable disconnected to stop the horrible noise.

So remove the cover from the binnacle, unscrew the drive cable from the speedo, and get somebody to watch the cable as you drive. if the cable end turns, the speedo is dead, if it doesn't the cable is dead.

Thinking back, I don't remember a transducer in my '89 cable, I think it was a single piece... but it was a while ago.

I have the same problem cable spins around but my speedo has gone dead i'm still waiting for a replacement on the bay

Speedo and Rev counter inop

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