No Tacho after accuspark and Ballast resistor

[ed_vh]

Hi,

I have a 1972 Elan +2S130 (UK) and I have just made the following changes to try to improve starting;

1. Replaced points with an accuspark electronic ignition
2. Changed back to the original configuration of a ballast type resistor coil

Now the car will start but the taco does not work. What is the likely cause (accuspark, ballast wiring or something else)? It should be noted it has not been running for 3 years so it could be unrelated to these changes!

The wiring diagram in my elan manual does not show the wiring for the balast type coil. When I originally had the car 10+ years ago it had a ballast type coil and the resistor broke. At the time I could only get a standard 12v coil so put that in and never got round to changing it back. I believe that I taped over the wire that provides the 12v that bypasses the resistor. This wire is pinkish with a very think yellow line. The wire that is on to the coil permenantly during running is the same colour without the yellow line (just pinkish). The workshop manual does not show the wiring for the ballast type resistor. Does anyone know the wire colours that I should expect for all the +ve side of the ignition and what should be wired to what?

Many thanks for any help.

Cheers

Ed

[UAB807F]

Hi Ed,

Reading your comments on the wiring, I'm wondering if what you see as "pinkish" was once actually white ? Try giving the insulation a scrape with a penknife and see what you get.

Although this link is for the Europa I think you'll find it relevant as it has coloured wiring diagrams which show the colour codes and wiring for both ballast & non-ballast coils. The one you want is half way down the page in the electrical section under the heading "updated and colorized wiring diagrams", and the TC (UK) is the one to look at. That shows white & white/yellow wiring codes.

http://lotus-europa.com/manuals/index.htm

As for the rev counter, well, that might just be down to the electronic ignition. There are lots of threads about various ignition modules and the performance with OEM rev counters. It's confusing because some seem to work ok, others work at first and then gradually pack up and you also have cases where the rev counter doesn't work from square one. If you put "electronic ignition rev counter" into the search box at the top of the page, you'll get enough threads to keep you going all day !

In my case I just gave up with the OEM one and installed modern electronics behind the old dial, which works fine with both CB points and the Pertronix system that I have.

Brian

[acoster]

I believe the +2s rev counter is RVI type and Accuspark would need RVC. If thats true you need to change the rev counter or its innards for a RVC type. I've just bought Accuspark for my Triumph TR6 and have built a custom rev counter from a Jag one (needed 120mm) using RVC innards from another gauge. Seems there are quite frequently RVC type rev counters on eBay. RVC is printed on the dial. If you decide to change look for 4 cyl not 6 cyl one. I believe these were fitted to later MGB's so should be plentiful supply. A rebuilt existing revcounter would cost between ?95 (a guy on eBay) and ?250 (specialist refurber)

[ed_vh]

Thanks for your very helpful advice. I have tried a few wiring changes that made no difference. Speedy cables will do the conversion for me for ?75 so I think I will need to go with this option (takes 3 weeks though!).

)

[Kerryt333]

Hi Ed,
Your 2 wires are as Brian said , white & white with a yellow trace, & it seems as though
you have the wiring right, the rev counter is not working because it is probably not suitable
for that type of electronic ignition.I have the simple Lumenition ignition on my +2 with a ballast resistor & have no problems with the rev counter.?75 seems reasonable for the conversion but why are they called Speedy cables with a 3 week turnround?
Regards
John

[ed_vh]

but why are they called Speedy cables with a 3 week turnround?

LoL - Very good point! If I point that out to them I fear they may be even slower......

[bob_rich]

Hi Ed

Assuming your Tacho did , or does, work before the fitting of the Accuspark I think the attached note should help. I have not used an Accuspark but the current to power up the electronics in the module can and usually does upset the RVI type tacho's.

I marked up a scan from the Accuspark data sheet with a wiring note which I am 99% certain should work if the tacho is OK
this wiring idea has worked on other Electronic ignitions I have encountered.

best of luck

Bob

[JJDraper]

If I point that out to them I fear they may be even slower......

Speedy compared to some specialists - well known UK distributor specialist wanted 8 weeks to refurb my Dizzy...

Jeremy
PS I used Speedy Cables a few years ago to deal with the 'bouncing Tach' problem - very happy. Used them to refurbish the speedo as well when it started being sluggish. Good value. No connection with them etc etc...

[ed_vh]

Hi Ed

Assuming your Tacho did , or does, work before the fitting of the Accuspark I think the attached note should help. I have not used an Accuspark but the current to power up the electronics in the module can and usually does upset the RVI type tacho's.

I marked up a scan from the Accuspark data sheet with a wiring note which I am 99% certain should work if the tacho is OK
this wiring idea has worked on other Electronic ignitions I have encountered.

best of luck

Bob

Thanks for this I will give it a try this weekend. I did try powering the accuspark module from the main battery cable into the engine bay rather then on the same terminal as the tacho connection but that made no difference.

Does the wire diameter make any difference? I am going to trial putting in the wire past the tacho you suggest with a 1.5mm2 section. Is that the right size to use?

Cheers

Ed

[bob_rich]

Hi Ed

1.5sq.mm. is more than adequate. As an educated guess anything above around 0.5sq.mm should be OK to power the Accuspark Electronics. Also check that no other circuit is fed from the coil +ve (SW) terminal . Sometime accessories are tacked on because the coil is, on many cars, a convenient point to pick up a bit of power. Again the current from such accessories will upset the tacho.

best of luck

Bob

[ed_vh]

OK, I pulled out the Tacho at the weekend. The back was not quote what I expected. I thought the white wire would be a continuous loop but instead the back looked like this;



The top white wire is onto a bullet connector. I didn't pull the bottom one too hard in case I damaged it as I was not sure what type of connector this is. No sign of the coil of white wire. Do I have to remove undo the screw so the part with the white wires comes off the back or do both white leads come off?

Any advice most appreciated

PS. Unfortunately some of the veneer on the dash decided to come away too! This will require some careful gluing back of the pieces. I cant face a complete refit of a new dash at the moment!

[RogerFrench]

Both white wires come off - one is a male bullet, the other female. The loop is inside the tach, not outside, on this slightly later design.

[ed_vh]

Thanks! Is it obvious which one is to the coil?

[UAB807F]

It's a continuous loop, so it all goes to the coil ? Does this picture help any ? You can see the twp connections and how the inner loop is formed. (this is a Europa tach, but it's basically the same as yours)

Brian

[ed_vh]

Thats good to see what is inside - thanks. Bob mentioned on his sketch above to wire it the 'right direction' so i am guessing it is important to know which end of the wire goes to the coil and which to the ignition. It might be obvious when I get home and look at it. I guess I can work it out with a volt meter.