300 Tdi tacho problem

[woollyfree]

99% of the time my tacho works perfectly. Then for some unknown reason it just dies. Cruising on the freeway yesterday, it did a couple of jumps then settled on the stop. The motor kept running, there were no other signs of trouble, just a dead tcho. When I got to the end of the freeway, it came back on again.:confused:
It did it again later so I pounded on the dash a bit to try and get a reaction, but nothing.
It doesn't seem to be related to road conditions, but who knows?

[p38arover]

The tacho is driven by a feed from one phase of the alternator. Check the connector at the alternator.

[woollyfree]

Never thought of the alternator, thanks I'll have a look.

[Bazzle218]

I do not wish to put a hex on you, but last month my taco did the same a number of times and then died. No warning lights on the dash but after checking connections and finding all ok, threw on a muliti meter and found Alternator had dropped its bundle. Confirmed at Auto elec, Alt dead $320 later taco works. Godo luck might also be the spade terminal at the back of the alternator. Give it a clean :p

[p38arover]

I do not wish to put a hex on you, but last month my taco did the same a number of times and then died. No warning lights on the dash but after checking connections and finding all ok, threw on a muliti meter and found Alternator had dropped its bundle. Confirmed at Auto elec, Alt dead $320 later taco works. Godo luck might also be the spade terminal at the back of the alternator. Give it a clean :p

Taco? :p

http://www.canyoninnsportsbar.com/attachments/Image/taco.jpg

[loanrangie]

Never thought of the alternator, thanks I'll have a look.

Pull the tacho feed wire off the alternator and give it a nip down with long nose pliers, re attach feed wire and it should be fine- mines been fine for 3 years.

[seano87]

Never thought of the alternator, thanks I'll have a look.

Exact same symptoms as you, mostly fine, would occasionally just drop, everything else was fine. Turned out to be the wire to the back of the alternator as others have suggested. Mine fell apart as soon as I touched it, put a new female blade type attachment end on it, hasn't been an issue since (almost 12 months).

Seano

[woollyfree]

Well it gradually got worse so I decided to have a go at the alternator connection. It looked OK, but with electricity you never know. Replaced it, full of hope, started it up and went for a drive.
Exactly the same as before.:(

so it looks like an alternator strip down to repair it. But as it's an auto, I'm not going to worry about it just yet.

[rovers4]

My spade term was getting hot from the nearby exhaust, thus easing the crimp pressure and letting the wire go.

Changed brand of crimp terminal. Much better, but still problems.
What rocking motion of motor there was, was fracturing the strands at the back of the crimp.

Had to change wire type and secure it to feeds to nearby d'light, hi beam, lo beam relays, for stability. Used silicon (high temp) insulated type - very flexible. Spliced it back to the original installed wire back near the heater air intake.

'luck,
Rovers4

[woollyfree]

Hmm. Didn't think bout the actual wire. Might check that tomorrow.

[TonyC]

99% of the time my tacho works perfectly. Then for some unknown reason it just dies. Cruising on the freeway yesterday, it did a couple of jumps then settled on the stop. The motor kept running, there were no other signs of trouble, just a dead tcho. When I got to the end of the freeway, it came back on again.:confused:
It did it again later so I pounded on the dash a bit to try and get a reaction, but nothing.
It doesn't seem to be related to road conditions, but who knows?

Hi Woolie,
I don't know how true this is but I have heard that if there is no load on an alternator then the signal that drives the tacho can drop off.
Next time it does it, switch on the head lights and see if the tacho comes back.

Tony

[groucho]

Hi Woolie,
I don't know how true this is but I have heard that if there is no load on an alternator then the signal that drives the tacho can drop off.
Next time it does it, switch on the head lights and see if the tacho comes back.

Tony

How come the tacho in all of my vehicles "diesels' work all the time
even with a fully charged battery????????

[TonyC]

How come the tacho in all of my vehicles "diesels' work all the time
even with a fully charged battery????????

Just one of those things floating around in my head!
It's easy enough for Woolie to test, just switch on the lights.

Tony

[woollyfree]

It has actually gotten worse since I refitted the plug on the wire attaching to the alternator. This makes me think it's either the wire itself, or the connection behind the plug on the alternator itself. As for working without a load, most of the time it has been playing up the A\C or the fan has been on so I doubt if that has any effect.
I hope to get som time to play with the wire next week, for now I've got to fix the rear drivers side door lock that doesn't unlock with the remote.:confused:
Locks fine, just won't unlock.