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haunted speedo -latest

Just to remind folk Miles the 300Tdi Disco has the electronic speedo which is driving me nuts as it suddenly jumps into high speeds while the car is standing still. Replaced the speed transducer which didn't make much difference .Recieved another instrument binnacle thru the post today, fitted still doing it. Another suggestion is the alternator might be producing the problem which I first noticed when the water pump started irrigating the engine bay so it may have contaminated the regulator pack, the tacho is however not giving problems. I gave the alternator a good squirt with degreaser then cleaned it with switch cleaner spray before drying off with the airline blow gun and it seems worse so I could be on the right track.Hopefully tomorrow morning when any cleaner that didn't get blown away will have evaporated so it might improve? It seems I am not alone have a look at this which is displaying the same symptoms

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you may have to turn up the brightness a tad. Derek

Reply to
Derek
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On or around Tue, 22 Jul 2008 23:49:27 +0100, "Derek" enlightened us thusly:

The tacho does that if the power supply is iffy. Had that on the bus, was an iffy fuse in the end.

Unfortunately, the ABS fault is not. It'll mostly accept a new fuse without eating it but any significant physical shock in the vehicle makes it blow. Taken the fuse up to 30A (meant to be 5) and it's still doing it, so it must be an intermittent short somewhere. Now I've got to try to find which bit of loom it runs through.

Could be in the ABS ECU, of course, but unlikely. Unless the innards of same have come loose.

Reply to
Austin Shackles

"Austin Shackles" wrote in message news: snipped-for-privacy@4ax.com...

Thanks Austin discount the ABS cos' it ain't got one. My thought is the power supply is different to the tacho coming from alternator pulses but the speedo relies on pulses from the transducer so if the supplied DC power to the transducer is 'dirty' with spikes caused by maybe a capacitor or diode breaking down it may give erratic readings - any sparks out there want to venture as to whether I am on the right path?

Derek

Reply to
Derek

On or around Wed, 23 Jul 2008 20:57:36 +0100, "Derek" enlightened us thusly:

ah, sorry, were divided by a common language here. I was talking about the tachograph on the minibus, not a tachometer in the LR, which is indeed as you say driven from the alternator.

I'd still go with a wiring issue creating erratic/spurious signals though. I know on the tachograph, a brief power spike in the supply can make it track all the way up to the top and then back.

solved my ABS fault - the semi-trained simian assembly workers at LDV hadn't secured the wiring loom correctly under the dash, allowing it to hit the pedalbox and eventually wear through the insulation on the live ignition supply to the ABS ECU, causing intermittent short when going over bumps etc.

Reply to
Austin Shackles

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