Connecting up Tacho

[VBRED]

I have the VS supercharge engine in my VB. I want to connect it up to a VH tacho cluster. My car was not fitted with a tacho originally so I don't think it has a tacho wire from the cluster. I want to know where on the cluster i connect the wire from my engine loom.

Thanks Pete

[VBRED]

I think I have it worked out. Top pin (-) Bottom pin (+) centre pin (pulse).

It would be good if some one could confirm.

Thanks Pete

[VK SL 3800]

Will not work as the ECU puts off a 5 Volt negative pulse (5v square half wave i think the technical term for it is) and is not enough to drive the tacho with the 12v power voltage, 12v signal is what its supposed to have. i found if you disconnect the alternator mine works, which is the same as effectively lowering the input voltage, so im going to buy this regulator Voltage Regulator Kit - Jaycar Electronics to keep the voltage lower and get mine working, ordering it tomorrow. Mine works at the lights at night with AC on as there is enough current draw to drop the voltage into the tacho and it springs to life but as soon as you take off again it dies as the alternator kicks in with the extra revs.

Ill let you know what happens in a week or so, Cheers Ben.

[VBRED]

So what you are saying that the 12 V has to be reduced to 5V in order for it to work? I would like to keep the original syle of cluster.

[delcowizzid]

there is a few ways to make it work one being a diode on each coil negative from dfi module joined into 1 wire to tacho or a pull up circuit to bring the input voltage to tacho up or you can mess round changing tacho input volts .we had the same issues but just fitted an autometer sport comp 2 LOL way easy

[VK SL 3800]

Im not exactly sure, it will work at 12v but when the alternator is running the voltage is around 13-14 which is too much, hook it all up and test it then unplug the alternator and see if it works then if it doesn't switch the headlights on and see which will further drop the voltage. I couldnt find a way to bring up the signal input volts from 5 to 12, i heard of a thing called an opto-coupler but it was getting to technical for me and i figured just dropping the input volts was pretty easy.

[Micho]

Hey guys i have a vt ss commodore and im installing an aftermarket tacho gauge. Can anyone tell me where the tacho signal wire is located, and if they have done this before.

[VBRED]

Hey guys i have a vt ss commodore and im installing an aftermarket tacho gauge. Can anyone tell me where the tacho signal wire is located, and if they have done this before.

Mate I reckon you would have better luck posting your question in the VT - VX section. This is VB - VK.

[VBRED]

KIM-055L DC-DC 12V Step Down to 5V 5A (Wide I/P 9-35V) (eBay item 260738586125 end time 17-May-11 20:47:35 AEST) : Business Industrial

Will this do the trick?

[VK SL 3800]

It should, im not sure what the optimum input voltage is yet and whether varying the voltage changes how accurate the tacho is. I bought the other kit and have soldered it all together but am yet to fit and test/have a fiddle. Apparently with the other one you may also need a heatsink, i havent worked out if i do or not yet, thinking no though.

[VBRED]

Any way I have bought it and will see how it goes if and when it turns up. Be good to get the tacho going. VK SL 3800 have you connected up your oil pressure gauge. I am assuming I have the wrong sender cause mine just goes to the far right.

[VK SL 3800]

No sender or an open circuit sends the gauge haywire, mines doing the exact same i though id broke a wire for a while and i couldnt find anything, so then i disconnected the other VK and it did the same thing. The oil gauge is next on the list of technical things to fix, im just going to get a T piece in the oil hole and run both the VP sensor and the original VK one. How you do it?

[180sc]

I had my gauge cluster modified by castle auto electrics so all my gauges would work with the ecotec waste of $800 that was. they supposedly modified my tach to work off the ecotec but it doesn't when i got it back from them i had to rewire it as they had stuffed it up leaving the handbrake light on constantly and the battery/charge light never worked (yes i checked globe) due to crossing wires, they also broke the temp gauge scratched the face of the volts gauge and broke in several places the cluster housing.
Changing to the l67 from a vt the only gauges that work are fuel volts and speedo as the vs uses 2 senders for temp one for gauge and one for ecu and vt gauge comes from ecu/bcm so it has only one sender so for that i have to change to a vs lower intake manifold or drill and tap the vt one for the vh sender. as for oil pressure i am going to do the same thing you suggested vk sl 3800 and run a t piece with the vh sender and the vt sender but i am going to see if the vt sender will work the gauge first as i haven't tried it yet.

SO if you guys figure out the tach it will be handy otherwise im going to do an autometer setup.

[VBRED]

My step down transformer has arrived. Not bad for $6. I will try and fit it this week end.

[VK SL 3800]

Hope it works, my regulator did but it got to damn hot so i didnt use it, im going to see the VDO agent and see what he reckons, there pretty switched on mob.

[VBRED]

This one has a heat sink of sorts. I am thinking of mounting it in the plenum under the bonnent vents.

[VK SL 3800]

Thought id update my position in regards to this problem, i dropped my whole cluster down to my local speedo shop while im replacing the clutch in my car and they said theyll be able to get it to work no worrys, they are going to test it makes sure its accurate as well, ive been quoted about 100 bucks to get it done. I believe they are going to use a little device called an opto coupler. or an item of similar effect. ill see how it goes.

[jpetrou]

Keep us posted, I am in the same boat too. (VK with 3.8 Ecotec).

[VK SL 3800]

Righto People, my VK now has a working tacho, $120 later though. Its accurate as well.

[180sc]

care to tell us how?

[VK SL 3800]

Hmmm hard to explain how it works, its a little electronic device that uses the 5v to flash a little light (like optic fiber) then the little chip sees it then allows a 12v current through while the light is on its all in a little unit the size of a $2 coin with i think 4 wires coming out of it, constant power, earth, input, output. Very simple to wire in just expensive.

[jpetrou]

Thanks for that VK SL 3800, thats good news. At least I can get my tacho to work again. As far as getting the original speedo to work off the 4 speed 4l60e trans, thats another story.

[VK SL 3800]

Speaking of this, i actually got them to give it an accuracy test yesterday as i was optimistic, its within 100rpm across the entire rev range which is good.