Intermittent speedometer

[Rob]

This weekend my speedometer has developed a fault. It started out by not working at all while driving around the farm track at Lincomb, and then started working after going over some potholes. On the motorway on the way back it worked most of the time but occasionally it was intermittent and the needle was jumping a lot, seemed to be affected by acceleration/deceleration which makes me think its a loose connection. I have looked at the connection on the transfer case and it seems fine. Is there an easy way to diagnose the fault? Where can I check for the speedometer signal apart from on the back of the instrument panel?

 

[Jon Wildsmith]

Not sure if Richard mentioned the location / description of the speed sensor wire behind the dash in the thread of mine about the Arduino gadget, worth a look.

 

[Rob]

Just to update this thread, all fixed after I replaced the speed sensor on the TC with a used one. IMO its not worth diagnosing as second hand sensors are relatively cheap to buy.

 

[Scott]

As some of you may have read, my 80 also recently suffered total and sudden loss of the speedo. At the time I searched the forum and found Rob's original post and PM'd him as to what fixed it, he kindly replied and also updated this thread.

I can also report that my speedo failure was also due to the transfer box speed sensor. Karl supplied a secondhand one to confirm my theory, and all was fixed. Just to add, my speed sensor failed without warning, and it's not forded that many rivers, so I'm not sure why it suddenly failed. I might source a brand new one so that I shouldn't have to worry about it again for another 18 years.

 

[Rob]

Glad to help

 

[Stix]

Rob, I have the same problem with my 80 - it's a 1992 Model. I replaced the Speed Sensor with a new one, and it didn't correct the problem. I did notice that there is a key-type device that couples the sensor to the speedometer cable. Could that part be the problem and do you know whether its available?

 

[Rob]

Speedometer cable? Not sure i follow as mine is a hall effect sensor with no cable at all. I replaced the hall sensor and it now works fine. If you do have a cable system then I would suggest following the trouble shooting procedure in the FSM.

 

[Stix]

I have the same problem with my '92 Land Cruiser. Speedometer is intermittent - mostly buried all the way to the right while driving. Odometer, and cruise control works normal. I checked to make sure all connection behind the instrument cluster are secure and replaced the Speed Sensor with a new one, but the problem still exists. Any suggestions?

 

[StarCruiser]

Stuck needle, or bad connection/ component/ coil in the speedo. If the odometer is fine then the fault must be in the meter I would have thought. Sometimes tracks can split on the flexi plastic PCBs that are used on the 80. Though I've not had it happen except on a touch pad for a microwave which was the same stuff.

 

[Dave2000]

Early 80's had a speedo cable. The electric failures are normally caused by transmission oil getting inside the switch and messing up the connections.

regards

Dave

 

[Stix]

Stuck needle, or bad connection/ component/ coil in the speedo. If the odometer is fine then the fault must be in the meter I would have thought. Sometimes tracks can split on the flexi plastic PCBs that are used on the 80. Though I've not had it happen except on a touch pad for a microwave which was the same stuff.

Thanks for the response

 

[StarCruiser]

I've had this problem on and off for a few years now. Looked it up and found the speed sensor oily so eventually earlier this year I replaced the speed sensor. Great, that's cured that I thought. Wrong, it came back this week after I returned from 10 days away. But this time, the needle stayed at zero for a couple of miles, enough to turn the odometer. Bingo, the fault is in the speedo itself!!

So took the dash apart,



took the binnacle out and removed the speedo

Seemed like the top tracks on the PCB were blackened. Thought this was by heat at first but there was no other sign of this. Gave it a light brush with a fine wire brush and the fault showed itself.


A broken track at the top of the board. So, soldered a small wire across and replaced it all in the reverse order after spraying a little lacquer on the PCB to stop any further corrosion and, so far so good, all works, no fault…but you never can be sure with intermittent faults so I'm still keeping my fingers crossed.



Pretty sure this is it. Only time will tell.

 

[froggy Steve]

well spotted! I hope it works OK now

 

[Gary Stockton]

Spare unit on eBay for £45

Item number 252065489357

 

[StarCruiser]

Thanks Steve, so far so good.

Gary, thanks for looking that up, I'm sorely tempted and the price isn't so bad considering I would get lots of spare lamps [emoji4] but, on balance I think I'm at least going to stick with this for a while and see just what it does.

 

[frank rabbets]

That looks like water cor0ssion damage doesn't it. Is it at the bottom of the board in situ?

 

[StarCruiser]

I agree Frank. But it's at the top of the board and there's no other sign. I can only guess at it being a residue left there from manufacture, but even that I find hard to believe.

 

[jungles]

Great post! had exactly same problem as you, followed your photos and found a different area burnt out bridged it with a wire soldered in and bingo!
thanks a lot

 

[StarCruiser]

Well done jungles!

I feel all warm inside. [emoji4]

 

[StarCruiser]

As an update this repair is so far 100% successful.
Now, if only I could find the cause of the vibration on my engine I would be a happy bunny!! [emoji36]