Advice please

[Guest]

Does anyone know if:

The wiring loom on all montegos is standard? What I want to know is that I want to fit rear leccy windows and was wondering if the cables to the switches and from the switches to the windows are already present or if I have to run new cables.

Secondly I have just been to the scrappy and got a new speedo with rev counter on it. When I removed it, it only had the taco cable conected and the rest where electricasl connectors. Mine doesn't have a rev counter but if I install the new speedo will it work or is there another cable I have to run?

Thanks

Nath

[Austin-Rover]

From trying to fit a Rev counter in my Maestro - you will need extra wiring for it to work as those electrical connectors that are already there have nothing to make it work. Not sure how to get it to work, but it can be done and i am sure someone will post how to do it...

[Mat_C]

I'm sure the wiring is already there for a tach. I shoved a dash unit with a rev counter from a montego into my C reg mk1 dash 1.3L maestro - worked fine!

[Guest]

It appears that most Maestros have the wiring for a rev. counter even if they don't have the rev. counter itself. However, there do appear to be a few exceptions to this. The base models (Special & Clubman in latter days) appear to be missing one wire from the coil to the edge connectors where the instrument panel slots in. I think the Haynes manual tells you that this wire should be white/black or vice-versa. It you want to do it properly, then you can solder an appropriate wire onto the track behind the edge connector. On the other hand, you can simply stuff the bared end of the wire into the edge connector and it will be held there when you put the instrument panel in. I have a feeling it's the left-most contact, but don't take my word for it. I can't remember how we worked it out, but it can't have been that complicated. Then feed the wire through the bulkhead and crimp the appropriate spade connector onto the other end to mate with the vacant blade connector on the coil. Ours has been working like this for the best part of a year now.

Hope this helps,

Peter.

[Austin-Rover]

Well, that explains why it didnt work in my Maestro - with it being a Clubman...

[e692wtt]

I had to wire in a 'fly lead' on my Monty 1.6L (88MY E-reg saloon) to get the rev counter to work, even though the wiring 'appears' to be there...

Not a great difficulty to overcome, though.

[H48HPE]

normal rev counters on petrols work off the coil but obviously a diesel doesnt have a coil. i think diesels take a reading off the alternator but im not sure. did any diesel montegos come with rev counters? if not id suspect that wiring may be a bit more complicated.

andy

[e692wtt]

'Diesel rev counters' use an AC feed off the Alternator, ie from the Alternator's output before it is 'rectified' into DC. This is via a seperate Alternator connection (extra) to the standard one that petrol-engined models use, and only applies, I think, to 'diesel-specific' alternators.

[Guest]

Bunged in the spare dash with rev counter and it works but. It goes straight to 7000 revs and it only goes up to 8000 so if you rev it a touch it goes of the scale. Does anyone know how to cure this??

Thanks

Nath

[H48HPE]

What car did you take it off i.e. petrol or diesel? perhaps the two are calibrated diferently

andy

[D813YBB]

One other thing to remember is there were 2 designs of instrument pods: one type with the rectangular reset button for the tripometer and a second type with the round reset button. The rev counter should work but try to replace like with like.

Regards
Martin

[Guest]

It was off a petrol version, but the trip reset swith was round which is the same as mine.


Thanks

Nath

[H48HPE]

just my way of thinking but it might make sense, the petrol rev counter will be sensing a pulse of current every time a plug sparks. meaning one pulse to one revolution. im not sure how the alternator method works but if it was sensing each time the current alternated it would sense two pulses for every revolution if it were geared 1:1 but it isnt geared 1:1 its geared to go faster than engine speed. I dont know how faster but lets say 1:4 for sake of argument. that would mean the current alternates 8 times per revolution compared to 1 pulse of current from a coil. therefore a rev counter calibrated to read from a coil but was reading from an alternator would read 8 times higher than it should

just a possible solution

andy

[Simon]

Yes, you need a divide by 8 circuit (simple electronics) to run a rev counter from a petrol model from the diesel's "W" post on the back of the alternator. I have a circuit diagram somewhere showing how this has to be done and if i can find it I'll post it up.

[MGTurbo]

I can confirm about the pulse rate being different, as i tried a petrol rev counter on my diesel. It would idle at 6000rpm! Does also mean the wiring is there for the diesel's, but some playing around would be needed.

Gareth