Rev Counter

[Alex_DJ]

Hi all

LORA has a Turbo Diesel instead of the normally aspirated one, and I have put a dash in that has a rev counter in it but it doesn't work!! Anyone out there know how I wire it up...can't find anything in the wiring diagrams in the Haynes :banghead: so... help????

[E_T_V]

Do a search and you'll find that it has been covered before. Basically you need to construct a circuit to drive the rev counter from the alternator W terminal (As the rev counter is driven from the coil on the petrol cars).

[Simon]

Use an LDV convoy Diesel rev counter or the guts from a diesel Freelander (I think) and wire it to the "W" connection terminal (a screwed rod) on the alternator.

[Rich]

I have sucessfully done the diesel rev counter mod, Simon kindly made the PCB for me based on the circuit diagram which will hopefully attach to this. The components can be bought from Maplins or RS easilly. I made mine fit into an old heated rear window relay box, so it would just plug in.

You will need wire to the pcb from the rev counter, one from a live when the ignition is on, an earth, and one to the W terminal. And as has been pointed out, this is a stud on the alternator, and not the spare spade terminal which I tried to connect to first, and made a big bang.

HTH Rich

[Alex_DJ]

You're a hero!!

Will have a go this week-end as I'm not DJ'ing...yet!!

[Steve H]

I have sucessfully done the diesel rev counter mod, Simon kindly made the PCB for me based on the circuit diagram which will hopefully attach to this. The components can be bought from Maplins or RS easilly. I made mine fit into an old heated rear window relay box, so it would just plug in.


HTH Rich

Any idea of how accurate this is? I suppose it depends on the step-up of speed between the crankshaft and the alternator by the pulley ratio, but how close to X8 is this? Just interested really....

Steve H

[Rich]

I think it does under read slightly, but I did have to subsitute a capacitor which I blew up after in-correctly connecting to the terminal which was not the W plug. It may be down to that?

I believe the EGR system which uses the W plug also uses the divide by 8 method to monitor engine speed, so I think that much is correct. Rover just never took a step further to make it run a rev counter.

[E_T_V]

If you measure the pulley diameters you could calculate how accurate it is.