rev counter wiring

[kevinchown]

Hi can anyone give me a simple break down as to how the rev counter is wired up on my 1967 2000 TC I have luminetion ignition and now the car runs fine but there seems to be no power to the revcounter and I'm not 100% sure as to how it is wired up
Cheers

 

[Demetris]

If the rev counter is original to the car, it should be wired in series on the line between the distributor and the coil.
You have to have a look at a wiring diagram to understand what i am talking about.

 

[kevinchown]

ok thanks will do

 

[kevinchown]

Hi I'm none the wiser regarding rev counter wiring I have 200tc with standard revounter, out of the back are one earth one yellow and white wire one black and white wire. when the yellow and white wire is attachedf to the negative terminal of the coil there is power to the black and white wire ?? also the car came with luminetion ignition and did work.. just not sure what it is supposed to be wired to!

 

[darth sidious]

Could you take pics of the rear of the rev-counter and the wiring that is behind? That would help I think!

 

[kevinchown]

Hi attached hopefully are the images ! the wiring is the yellow & white wire and the black & white wire go to the two bullet connections, there is another black and white connected to the spade, which I presume is the main earth, plus the smaller wires for the lamp what I can't work out is what they are connected to in the engine bay..

 

[darth sidious]

Fist and foremost, damp squid time.

Lumention state that there are some cases where RVI (current sniffing) rev-counters like yours won't work. However, I have a feeling (but no tangible real-life experience to back it up, I hasten to add!) that only happens on cars

1) which have the RVI sniff terminals wired/placed between the ignition-switched supply and the coil + terminal (as on 71/72 P6's - but not yours, I think)

and,

2) when the supply for the Lumenition unit is taken 'after' the RVI (that is, the supply current for the unit also goes through the sniff terminals)

Again, I may be wrong with those 2 theories!

Hi attached hopefully are the images ! the wiring is the yellow & white wire and the black & white wire go to the two bullet connections, there is another black and white connected to the spade, which I presume is the main earth, plus the smaller wires for the lamp what I can't work out is what they are connected to in the engine bay..

No, the spade wire is the 12v supply, which should be an ignition-switched live (a live which is switched via the ignition switched - see picture). The earth is connected the the frame of the rev counter. I'm wondering if that is the reason here...



In the original wiring (and assuming negative earth [which most, if not all, TC's are?]), the wire (white with a slate/grey tracer?) from the coil - terminal (aka coil CB terminal on older coils) comes back into the car behind the dashboard, terminates in a female bullet on the end of the wire, which then mates with the male bullet on the rev-counter. The female bullet on the rev-counter mates with the male bullet that terminates on the (white with a black tracer?) wire which then goes back into the engine compartment and ends up connected to the distributor.

From your previous description, I am assuming that you have a white wire with a yellow tracer coming from the coil - terminal which ends up behind the dash and terminates in a female bullet. That female bullet mates with the male bullet on the rev-counter. The white wire with a black tracer, again I am assuming, has a male bullet terminated on the end behind the dash, and goes back into the engine compartment and is connected to the (brown, is it?) wire from the Lumenition unit.

 

[kevinchown]

Hi thanks for the help, it seems a step in the right direction.. At the moment I think I now have the correct power to the spade terminal from ignition, the yellow and white wire to the negative terminal, but there is no obvious attachment for the black and white wire to the distributor. I I tried various options. One of which is to attach it to power line from distributor , rev counter appeared to work the split second before engine die each time I try and wire it in the engine dies???

 

[darth sidious]

Hi thanks for the help, it seems a step in the right direction.. At the moment I think I now have the correct power to the spade terminal from ignition, the yellow and white wire to the negative terminal, but there is no obvious attachment for the black and white wire to the distributor. I I tried various options. One of which is to attach it to power line from distributor , rev counter appeared to work the split second before engine die each time I try and wire it in the engine dies???

1) Are you sure the white/yellow wire is actually connected to the - terminal on the coil?

White/yellow on the later cars (at least) was the wire colour for the + terminal of the coil. Not that I don't believe you, it's because I now seem to recall disconnecting a white/yellow wire from the back of the tacho on the donor series 1 J-reg 2000TC we used to convert our old 2000Auto to a manual...

2) The Lumenition module under the bonnet. What colour wires does it have, and where do they connect to?

I've got the feeling you're (unintentionally, of course!) shorting out 1) the coil +12V supply or, 2) the LT from the coil - terminal to the module.

When I said "to the distributor" in the picture, I was meaning as it was wired when the car was built;
i.e.

coil + terminal --> coil - terminal --> wire from coil - terminal which runs into the car behind the dash (and terminates with a female bullet on the end of the wire. The female bullet mates with the male bullet on the tacho) --> male bullet on the tacho --> female bullet on the tacho --> white/black wire which has a male bullet (that mates with the female bullet on the tacho) which then goes back under the bonnet and ends up connected to the spade connector on the side of the distributor.

I think you need to locate the other end of the white/black wire and see where it ends up under the bonnet.

 

[a15htn]

Something I've mentioned before, this can happen with electronic ign and RVI tachos (although I was told I was wrong :roll: ) The easiest fix is change to an RVC tacho which WILL work straight off.

These are available on later MG's and mine was £20 off Ebay...... Works fine with electronic ign module and a ballasted coil, straight away no fuss

 

[kevinchown]

Hi pretty sure that the white and black wire is routed to around the coil but will try again, I'm sure that when I attached to a spade conection that I put on the outside of the distributor, which connects to inside which I think is just earth?/ the car stalled but will try again with yellow and white wire on the positive terminal on the coil. As fopr the wire coming from the distributor's luminetion they are red blue and black and again car stalled when I offered up the black & white wire to the red & blue wires ???

 

[darth sidious]

Something I've mentioned before, this can happen with electronic ign and RVI tachos (although I was told I was wrong :roll: ) The easiest fix is change to an RVC tacho which WILL work straight off.

These are available on later MG's and mine was £20 off Ebay...... Works fine with electronic ign module and a ballasted coil, straight away no fuss

Ah, but you knew which wire went where. We're still not entirely sure which wire goes where here...

 

[darth sidious]

Hi pretty sure that the white and black wire is routed to around the coil but will try again, I'm sure that when I attached to a spade conection that I put on the outside of the distributor, which connects to inside which I think is just earth?/ the car stalled but will try again with yellow and white wire on the positive terminal on the coil. As fopr the wire coming from the distributor's luminetion they are red blue and black and again car stalled when I offered up the black & white wire to the red & blue wires ???

If the car's running with the white/yellow on the coil - terminal, then leave it be! You'd only be likely adding more confusion to the issue!

This is a picture of a Lumenition module.



Apologies for the quality, but notice there are 6 wires coming from it. 3 (red, black, and blue) are bunched together. These go to the "eye" within the distributor, and I think red and black are the + and - supply to the "eye" respectively, whereas the blue is the signal wire. (I think the "eye" within the distributor is electrically isolated from the metal of the distributor (possibly to make it work with either +ve or -ve earthed cars), hence the need for + and - supply wires)

The other 3 wires:-

Red is the + supply to the Lumenition module,
Black is the - supply to the module, and
Violet (purple) is connected to the coil - terminal. Some modules use brown instead, so I'm led to believe.

Where is the module and where are those wires on your car?


If the car is running, then the violet (or brown) wire is connected somewhere. That's the wire we are looking for!

Could you take a pic of the coil (and Lumenition module would be great too!), btw?

 

[kevinchown]

Hi thanks for the info but I fiddled around with the connects and I think i may have shorted out the lumnetion 'eye' cause now the car won't start! soon as I've storted that out I'll be back on it, thanks to you all for the info so far!