Disco 1 tachometer "jumpy"

**gazby** · 31st March 2011, 04:17 PM

Hi, I have a '97 Disco 300Tdi, just recently the tachometer has been very unsteady and seems to jump and waver in the order of plus or minus 400rpm when cruising along at highway speed, this also occurs at lower rpm but not so much at idle.
The engine is running great and apart from the fact the tach has been fine for the past 230,000 klm it seems to not bother anything but the driver.
Anyone have an idea if this is a common problem with old Disco's, and if so how hard to fix, I have been through the fuses checking for a fried or loose one, the problem persists, any help appreciated.

**River** · 31st March 2011, 04:34 PM

i had a similar problem on my recently purchased 95 300tdi, check the connection, white wire on the back of the alt, i replaced the splade with a new one and has been fine every since

**dullbird** · 31st March 2011, 05:58 PM

and if its not that check the integrity of the serpentine belt as well as the pullys especially the one on the alternator

**shining** · 31st March 2011, 06:19 PM

And on a similar but completely different vein, When the speedo (95 300Tdi) stops working and then flicks around all over the place, then is normal for a while then goes crazy again....how many things can it be???

**SimonM** · 31st March 2011, 06:53 PM

Originally Posted by shining

And on a similar but completely different vein, When the speedo (95 300Tdi) stops working and then flicks around all over the place, then is normal for a while then goes crazy again....how many things can it be???

I thought this was just my Disco being a Land Rover.

**zuno555** · 1st April 2011, 06:41 AM

Both problems are in fact the same (in 99% of cases), just loose connections. I have had both occur.

For the tacho alternater connection I just bent the connector a bit to give a tighter fit - all good.

I drove for a couple of weeks with no speedo thinking it was something serious before I looked into it - the connection on the transfer case had fallen off. Put back on and voila, all fixed. It was jumping erratically before it "died" as well.

**ade** · 1st April 2011, 06:23 PM

when my 95 disco was doing the same it was the transducer on the tranfer case just near the handbrake drum

**German Grüner** · 2nd April 2011, 01:24 PM

You must check the contact between connector and the crimped cable, too. I found mine was wrong there, so connector pressing didn't brought the solution.

Regards

Saber1 · 4th April 2011, 12:06 PM

I had that problem with my '97 tdi. Turned out the alternator was due for a rebuild.

**gazby** · 8th April 2011, 04:05 PM

Thanks to all you guys who posted ideas for solutions to the tachometer problem it was indeed the white wire on the back of the alternator it must have been on the little lug but not making constant contact, I simply removed the wire and crimp spade then pushed it back on again, problem solved tacho steady.
I may also at a later time follow some more of the advice here and fit a new crimp to the wire to ensure a proper fix, many thanks to all.

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