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Mammal
8th May 2008, 10:55 PM
G.Day please can anyone help me on this. I have a 1999 Disco TDi and she has developed an annoying trick , The Taco. intermitantly drops to zero then after a while back up to around the 2000rpm mark. I suspect a short or loose connection but where on earth is the connection? Please help its driving me nuts

Xavie
8th May 2008, 11:06 PM
hahaha. mine does the same thing. The speedo is wrong too!

Now as for what it is.... I can't think of the part it needs so I guess you will just have to wait for one of the many people who can actually give you an answer. I remember all these things about the part it needs but not the name. How annoying.

Xav

Disco_owner
8th May 2008, 11:33 PM
hi mate ;

check this thread;

http://www.aulro.com/afvb/technical-chatter/25156-discovery-i-speedo.html

it may/maynot help

Lotz-A-Landies
9th May 2008, 12:07 AM
Hmmmmm

I didn't know that diesels eat tacos! Do you add it to the fuel tank or do they munch it through the air cleaner? :D:D:D:D

Do you know that the many of the Range Rover classic V8s have a pulse source generated from the alternator which is used for the tachometer this is likely to be the source on a Tdi (although I'm only guessing.) The symptoms you discuss are the same symptoms that I get on my RRc when I have alternator problems. When the alternator stops charging the revs indicated on the tacho will drop to zero. You will also notice a delay before the revs come up when the engine starts.

My first plan would be to check all the terminals on your alternator, then get it checked by a sparky.

Diana

Disco_owner
9th May 2008, 12:23 AM
Hmmmmm

I didn't know that diesels eat tacos! Do you add it to the fuel tank or do they munch it through the air cleaner? :D:D:D:D

Diana

no, but their drivers do ! you add them to your fuel tank , AKA Belly.:D:D:D

Mammal
9th May 2008, 06:56 PM
Thanks Disco Owner I checked out that thread and still wonder if the "TACHO" is connected to the transducer the same as the speedo?

Blknight.aus
9th May 2008, 07:22 PM
the TDI's take the tacho input from the alternator.

its normally a problem with the plug itself getting loose/corrosion but as its wired into the same part of the alternator guts that provides the excitation it will sometimes help indicate an upcoming failure of the alternator if its not just the plug being problematic.

rovers4
9th May 2008, 08:43 PM
Yes, the tacho feed comes from the alternator, on the tab marked "W".
It is the exciter signal.

Mine (97Def 300tdi), went crook just like yours is indicating. The alternator eventually stopped putting anything out. Very expensive to replace.
A sealed/unservicable unit. SORRY!!!!!:( :(

It got replaced with a higher output unit that is serviceable. I believe that the originals are no longer available.

Hope you get a new one in before the old one gives up.

Rovers4.