Hello Folks,

I've got a 2000 Felicia 1.9D with 164,000 miles on the clock. She's running well but lately I've noticed that the rev counter doesn't register immediately after starting the engine.

Then, this morning, after a 40 mile journey, it dropped to near zero with the engine idling normally in stationary traffic. When it did this, I heard what can only be described as a light scraping noise from the engine bay. It went away with a dab of the throttle and the rev counter jumped to 1500 rpm and worked normally again.

Any ideas? I do most of my own servicing and repairs - Is it a big job to fix?

Thanks guys.

Hopefully someone who actually has experience with a diesel Felicia can confirm this, but looking at the diagrams the diesel gets its tacho signal straight from the alternator on the yellow/green wire, so I'd start by checking along the wiring to make sure all connections are clean and secure, and also that the drivebelt isn't slipping and the alternator pulley isn't loose (possibly more likely than an electrical issue given the noise symptom).

Hello Robin,

I'd no idea the tacho took its signal from the alternator - that was a sound piece of advice. I checked the wiring from the alternator and it seemed ok, as did the pulley. The drive belt looked like it had been in there since Methuselah was a boy so I've put in a new one - a fiddly job for an 18-stone Ulsterman with none too delicate hands!

The problem seems to have gone away now. The tacho's working fine and the noise isn't there anymore (presumably that was the belt slipping).

So thanks again for your help.

whoooa.. hang on, no the tacho gets it's signal from pin 1 on the ecu

whoooa.. hang on, no the tacho gets it's signal from pin 1 on the ecu

Which is also connected to...?

I assumed it was the other way round, and that the ECU recieved the RPM signal from the alternator (with the tacho feed tapped off the middle), seeing as there's no other obvious RPM sensor. That and the fact that that setup would explain the given symptoms. Sorry if I was wrong, but I'm glad that seemed to solve the problem

actually i've been applying some lateral thought to it, you must be right.. the W terminal is just a stator tap, the alternator pulley must be 1/3 of the diameter of the crank pulley which would mean you get 1 'pulse' for every 1 revolution of the engine becuase it's a uses 3-phase windings.. makes perfect sense in my mind now.. i mean how else would the ecu know how fast the engine is turning..

Looks like I started a bit of a debate there.

I'd originally thought it would be similar to the speedo, with a cable taking its drive from the camshaft - just like in the good old days before they started filling cars with electronics.

Anyway, thanks to both of you for your help (and enlightenment) on this one.