Sii · Jul 3, 2012

Hi Guys

This is my first post but been reading a few months. Got a bit of an odd issue with the speedo.

I have a '89 plate Range Rover Classic went to start it at the weekend after it had sat for just over a week and the needles on the rev counter and speedo went up to the max. Checked the battery and it was flat, charged it up and put it back on starts fine and the rev counter is working fine but the speedo needle is pointing straight down and doesn't move when driving.

Just wondered if anyone has come across this before? Thanks in advance for any help.

Si.

Saint.V8 · Jul 3, 2012

I think the '89 is a mechanical drive on the speedo, what I mean by this is, there is a mechanical cable from the speed drive to the speedo, this then spins a set of magents in the speedo which are connected to the needle........

Take the binnacle off, and check the drive cable, it may be that the needle has spun on the drive spindle past the stop and now it cant go back the other way.

Pete The Biker · Jul 3, 2012

Strange!

As it's a mechanical drive, why would the speedo needle have moved when the car was first started - especially to the max?

The rev counter is driven by a signal from the alternator so why should that have gone to the max? Though as it's electrical you could perhaps understand that some strange electrical gremlin was causing a problem.........

Peter

Saint.V8 · Jul 3, 2012

If there was a spike, the tacho would jump - as for the speedo, if the magnets just happen to line up at the wrong point, the needle will jump, whilst it is very remote, it may just happen.

Also I am only guessing it uses magents, it may be the mechanical drive cable rotates a small genny or pot in the binnacle, which in turn drives the needle - a spike of elec, could cause the needle drive to jump....

All I know is the Speedo drive is driven from a cable in two parts (joins in the dash somewhere I think) from the speed drive unit on the transfer box to the speedo in the dash.

Datatek · Jul 4, 2012

Saint.V8 said:
If there was a spike, the tacho would jump - as for the speedo, if the magnets just happen to line up at the wrong point, the needle will jump, whilst it is very remote, it may just happen.

Also I am only guessing it uses magents, it may be the mechanical drive cable rotates a small genny or pot in the binnacle, which in turn drives the needle - a spike of elec, could cause the needle drive to jump....

All I know is the Speedo drive is driven from a cable in two parts (joins in the dash somewhere I think) from the speed drive unit on the transfer box to the speedo in the dash.

There is no way a mechanical speedo will jump like that unless the car moves, it is driven by a rotating magnetic disc face to face with a steel disc attached to the speedo mechanism. The usual problem with those is oil creeping up the cable and getting between the 2 discs.
If it shot up while stationary, it's electronic and most probably an alternator or connection problem, although some cars have a voltage regulator for the dash instruments that can fail. The needle may have just gone beyond the end stop and is unable to return. Removal of the speedo and a gentle prod may be all it needs

Saint.V8 · Jul 4, 2012

Datatek said:
There is no way a mechanical speedo will jump like that unless the car moves, it is driven by a rotating magnetic disc face to face with a steel disc attached to the speedo mechanism. The usual problem with those is oil creeping up the cable and getting between the 2 discs.
If it shot up while stationary, it's electronic and most probably an alternator or connection problem, although some cars have a voltage regulator for the dash instruments that can fail. The needle may have just gone beyond the end stop and is unable to return. Removal of the speedo and a gentle prod may be all it needs

I wouldn't have thought a Mech drive would jump - but this is a Range Rover and anything can happen..!!

The manual I have for the '89 shows the speedo drive as a mechanical drive, but you never know what previous owners have done, so could have been retro fitted with an electronic version....

I agree with you Datatek (and as I mentioned previous) sounds like the needle has slipped on the pin or is the wrong side of the stop peg...

Sii · Jul 4, 2012

Thanks for your answers guys. I think it is an electronic issue as when I checked the battery it only had 8.4 volts across the terminals.

It is a late '89 I believe so I've found some bits from the 1990 manual have applied to it.

I'll try taking it out later and see what happens!

Saint.V8 · Jul 4, 2012

Sii said:
Thanks for your answers guys. I think it is an electronic issue as when I checked the battery it only had 8.4 volts across the terminals.

It is a late '89 I believe so I've found some bits from the 1990 manual have applied to it.

I'll try taking it out later and see what happens!

Yep, my 1990 model manual indicates an electronic speedo.....

Take the binnacle out and see if the needle has moved on the spindle.....yer never know.

pete12345 · Jul 12, 2012

im a newbie to this but i had same problem on mine when the alarm was triggerd about a month ago but the speedo needle went straight back have u had any alarm triggered messages

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