Hi, I have a 1996 Terrano TD27T / Auto transmission with electronic speedo.
For a few years now the speedometer/odometer has stopped after a long trip. Goes well with no problem on the trip, however as soon as the vehicle is cool, it doesn't go next time. After a while it starts working perfectly again. Doesn't ever give problems with short running, However problem is getting worse in the sense that it is taking longer to restart (Speedo) again after it stops.
The vehicle doesn't get used in water. There is no obvious problem around the loom and plugs near the transmission.
The gear changes /T.C. lockup work perfectly.
Where do I look, and how do I test? Is there a known problem with these?
Many thanks- Cheers Peter
96 terrano Speedo fault
Moderator: Mark
Re: 96 terrano Speedo fault
You need to put a scope on the speed sensor on the gearbox when its playing up and work back from there.
Does the auto shift ok when the speed isn't working? Often if there is only one speed sensor on the gearbox the signal will go to the exit and then to the dash from the ecu.
Search online and try and find a wiring diagram.
Matt.
Does the auto shift ok when the speed isn't working? Often if there is only one speed sensor on the gearbox the signal will go to the exit and then to the dash from the ecu.
Search online and try and find a wiring diagram.
Matt.
Re: 96 terrano Speedo fault
Thanks Mattman,
Yes the gearchanges etc are fine. I'll try searching online for a wiring diagram, however I'm hopeless at getting the right key words.
In the mean time if someone knows if they have one sensor or 2 would help me, as this could rule the sensor out if there is only one I suppose.
I'm not sure what you mean by the word exit - You said 'goes to exit, and then dash from ecu" or something like that.
I don't have a scope. Can I use a multimeter or something? I guess I would be looking for a voltage or pulsing?
Yes the gearchanges etc are fine. I'll try searching online for a wiring diagram, however I'm hopeless at getting the right key words.
In the mean time if someone knows if they have one sensor or 2 would help me, as this could rule the sensor out if there is only one I suppose.
I'm not sure what you mean by the word exit - You said 'goes to exit, and then dash from ecu" or something like that.
I don't have a scope. Can I use a multimeter or something? I guess I would be looking for a voltage or pulsing?
Re: 96 terrano Speedo fault
Should have said ecu not exit...
The signal from the speed sensor can't always be read by a meter.
Sounds like you need to visit an auto sparky.
The signal from the speed sensor can't always be read by a meter.
Sounds like you need to visit an auto sparky.
Re: 96 terrano Speedo fault
It's a seperate sensor on those. Located at the rear RHS housing where the output shaft is. Possible that the sensor has partially seized or spinning the cog without driving the hall-effect device or whatever it is they use.
I assume the odometer also stops? If so then the most likely culprit is that sensor, there are a number of instances of them faulting (although perhaps not in exactly the same way). If the odo is still ok then it'll be a problem with the speedo head.
It's a reasonably easy job to take out the sensor and have a visual inspection of it if you've no other test gear. IIRC it's a single 10 or 12mm head bolt holding it in, the sensor itself is maybe 25mm in dia and will stick out a little from the housing - should be obvious. It could be stuck in place and may require some gently persuasion to remove it.
P.
I assume the odometer also stops? If so then the most likely culprit is that sensor, there are a number of instances of them faulting (although perhaps not in exactly the same way). If the odo is still ok then it'll be a problem with the speedo head.
It's a reasonably easy job to take out the sensor and have a visual inspection of it if you've no other test gear. IIRC it's a single 10 or 12mm head bolt holding it in, the sensor itself is maybe 25mm in dia and will stick out a little from the housing - should be obvious. It could be stuck in place and may require some gently persuasion to remove it.
P.
Re: 96 terrano Speedo fault
Yes it is both the speedo and odometer.
Thanks for advice about the sensor. I'll pull it out and have a look.-so it is drivers side near output shaft?
To me it seems to be related to long running/temperature, so I think the sensor is the likely culpit rather than wiring.
I forgot to mention that this vehicle does alot of sitting around. It last sat untouched for 1 year and I got in it an drove it almost 1000km that same day. (pretty much the same situation when it first did it 2-3 years ago) Mentioning about seizing is interesting. I didn't think there would be any moving parts. Mentioning about cogs and seizing surprised me. I'll understand it better once I get it apart.
Does the wiring go direct to the dash /speedo, or does it go through something else?
Thanks for advice about the sensor. I'll pull it out and have a look.-so it is drivers side near output shaft?
To me it seems to be related to long running/temperature, so I think the sensor is the likely culpit rather than wiring.
I forgot to mention that this vehicle does alot of sitting around. It last sat untouched for 1 year and I got in it an drove it almost 1000km that same day. (pretty much the same situation when it first did it 2-3 years ago) Mentioning about seizing is interesting. I didn't think there would be any moving parts. Mentioning about cogs and seizing surprised me. I'll understand it better once I get it apart.
Does the wiring go direct to the dash /speedo, or does it go through something else?
Re: 96 terrano Speedo fault
Yes it is drivers side and there are at least one if not two sets of connectors between the sensor and wherever it connects to in the cab (ECU or Speedo). Mine has I think one directly around the sensor and one under a removeable plate aiong with a a number of others associated with the gearbox/transfer case.
Good luck with the job, I'm sure all will be revealed once you get it out of the housing - it's just a small nylon cog driving the sensor device itself, looks much the same as 'normal' cable-driven speedo drive cogs. It'll be interesting to see if it's at fault or something else given what you say about the vehicle usage. I guess where the cog/shaft is it may get some condensation that could be messing things up a little if it sits around for a while.
P.
Good luck with the job, I'm sure all will be revealed once you get it out of the housing - it's just a small nylon cog driving the sensor device itself, looks much the same as 'normal' cable-driven speedo drive cogs. It'll be interesting to see if it's at fault or something else given what you say about the vehicle usage. I guess where the cog/shaft is it may get some condensation that could be messing things up a little if it sits around for a while.
P.
Re: 96 terrano Speedo fault
Yep - got it out, but I'm pretty confident that it all looks in order. Cogs good and shaft turns fine. I put a meter on the wires and it has resistance which changes when you turn the cog.
Really surprised the sensor was built like that. I was expecting a reluctor built into the transmission and just a magnet pickup, and no shaft or cog.
I guess the next step is to remove the instrument panel and cluster and go from there. I guess that if I plug the sensor back in, I can find the wires at the cluster/ head end, retest, and then this will leave me with the cluster to sort. I've never seen an electric one before. Any heads up on what to check with these? (bearing in mind that both the speedometer and odometer stop at the same time)
Cheers - Peter
Really surprised the sensor was built like that. I was expecting a reluctor built into the transmission and just a magnet pickup, and no shaft or cog.
I guess the next step is to remove the instrument panel and cluster and go from there. I guess that if I plug the sensor back in, I can find the wires at the cluster/ head end, retest, and then this will leave me with the cluster to sort. I've never seen an electric one before. Any heads up on what to check with these? (bearing in mind that both the speedometer and odometer stop at the same time)
Cheers - Peter
Re: 96 terrano Speedo fault
Ok, good you've done that - bear in mind though that is could have an intermittent fault.
The cct diagram shows a 'unified meter control unit' that the sensor and speedo are connected to with the two connectors I noted before. If it helps it should be terminal 16 abd 14 that are the from the sensor - you could try checking for something here under the fault condition, that would narrow things down a bit.
Cheers, P.
The cct diagram shows a 'unified meter control unit' that the sensor and speedo are connected to with the two connectors I noted before. If it helps it should be terminal 16 abd 14 that are the from the sensor - you could try checking for something here under the fault condition, that would narrow things down a bit.
Cheers, P.
Re: 96 terrano Speedo fault
ended up re soldering the circuit board on the back of the speedo. Nothing obvious, but seems to have done the trick. Fingers crossed it doesn't happen again.