Speedo And Mileage Not Working

[benbenukuk]

Hi, The Speedo And Mileage are Not Working on my rrc any ideas of how I can sort it out, I have no ideas as I only got it to day, thanks.  Ben

[Range Rover Blues]

Speedo and odometer go hand in hand.

Firstly then what year?

Earlier ones had a mechanical drive form the gearbox.  A favourite is for the right angled drive on the back of the speedo head to pack up, the gears are cast in White Metal (Babbit's metal) and are cack.

Any 3.5 and 1988 3.9s would have this speedo, it looks like the SD1 speedo if that helps.

When hot wire EFi came in on the last 3.5s it needed a road speed signal, so the speedo cable is interupted by the transducer bolted to the chassis rail alongside the gearbox, if you have one of these rare beasts then there's an axtra set of cable joints to check.

If it's a 1989 3.9 or later, with a more traditionally shaped speedo (that you can actually read by the dahboard lights) then it's an electronic unit.  This is driven by a transducer (same as described above) and is fully electronic, the sensor pulses (inside is a reed switch) are filtered by the road speed buffer, a white box that looks like a relay.  The signal is shared by the cruise control and the EAS too, so if you have those then check if they work, if you don't you can check for the road speed signal at the engine ECU.

Confused yet :)

[Guardian.]

 :shock:ANd i was just gonna say change the cable. :)

[barriesheene]

Bl@@dy hell  :shock: I'm glad mines working  :?

[ChrisV8]

If it's the electronic type could be as simple as a blown fuse, that's what happened with daughters just after MOT, do the indicators work ? Cos I think it's on the same fuse !

[benbenukuk]

it's a 1989 and the indercators work fine but the hazzards don't.  Ben

[Range Rover Blues]

I wouldn't put money on it but I'm going to guess it's the electronic one then.

IIRC the ignition feed to the instruments feeds the rev counter, speedo and fuel/temp guages.  So does anything work?

I don't remember offhand but I think the ignition light might also be on the same feed :?

Anyway, it's possible the speedo has failed but first you should check that all the inputs are as they should be, that it's earthed, it has power and the road speed signal is working.

You can check it using a meter, if you turn the roadwheels slowly then the input should alternate between 0 and 12 volts a couple of times per rev, you need one wheel on each axle up in the air though.  (As I said earlier, if the cruise is working then the road speed signal is present, either way you should then check it's getting to the speedo itself.)

If you need any details let me know and I'll dig out some books, though TBH if you get the speedo in your hands you should be able to figure out what's going on.

[benbenukuk]

The oil temp, rev counter ect works all that doesn't is the speedo the milage counter and the milage thing under the counter that you can push the botton in to reset it, thanks.  Ben

[Range Rover Blues]

Ah, speedo, tripmeter and odometer.  Sounds like a break in the road speed signal cable then.

[Skibum346]

Not trying to take over the thread or anything... but what's your sugggestion for a 1993 LSE where everything works but the trip reset button doesn't reset the trip?

Skibum

[benbenukuk]

o.k where will I find the speed signal cable  :?

[Range Rover Blues]

Now you're asking.

If you can get the back off the speedo pod you houls find there are only 3 or 4 wires on the back of the pseedo itself and it's one of them, not eh one that's always live and not the earth, if you follow me.

IIRC they are in a plug on their own, but I wouldn't swear to it and I don't have a spare one handy.