VK Tacho to Blue Motor

[Mr 84]

I have been getting some work done to quell the rust and leaks in my VK's boot. While she’s been out of action I’ve decided to finally look into fitting a stock tacho in favour of the infamous vacuum gauge! I took the cluster out and have had it re-conditioned (looks near new!).

The new cluster housing is from a Berlina, so it has the necessary tacho connections for the plug. The fellow who did the work for me, has marked which prongs are associated with the tacho. It seems my car’s loom has 2 wires that correspond with the tacho prongs on the cluster (1 is a darker green, the other brown). However being my girl is the basic model, she came factory with a vacuum gauge. Does anyone know if these wires are connected? I suspect at least one goes to the EST computer?

I am also wondering; since my beast has a Blue 202 instead of a Black, the EST computer is not being used. It is still plugged into the loom however. My assumption is that the tacho wires (if connected) are/is still attached to the EST. If I were to cut one of these wires in the loom (near the grommet in the engine bay) and run it to the coil, would there be any issues with the EST or general running of the car? Also are the return wires usually brown, because the other wire associated with the tacho is brown?

Cheers.

Mr 84.

[dags061]

I have had the same problem but now have it sorted.I used a VB 6 cylinder sports dash with the 6 cyl tacho and hooked it up and it didnt work. I dad to run 2
wires from the coil and an earth and connect them where the 3 prongs go into the dash. Top wire is NEGATIVE, Middle wire is EARTH, Bottom wire is Positive.
I used a screwdiver and pryed the clips out where the prongs go in the dash and then solded them in. It seems that cars were not fitted with wiring for tachos if fitted with vaccum gauges. Hope this helps.

[Jonno]

All I know is one will go to neg on the coil

[Mr 84]

Ah cheers. I hooked my tacho up recently to test it and had the same thing - nothing happened. I've been looking around for wiring diagrams and haven't found quite what I need yet. Upon talking to the speedo man, I was told the Brown wire is the one associated with the tacho. The green wire is for the temp gauge, he made the mistake of writing a 'T' by both prongs without distinguishing. So to my understanding what I need do now is just splice the brown wire and run it to the coil! Thanks, any other advice welcomed!

[L67 Calais]

I took the cluster out and have had it re-conditioned (looks near new!).

Mr 84.

Hey mate, Where did you get this done? I need my cluster fixed up BAAAAD!!!!

Cheers, James.

[VK SL 3800]

I have a sneaking suspicion that if you plug it in it will work as i also had a look at my wiring but got rid of the 202 before i plugged the dash in.