Hi all,
I recently got my 5L LX Torana up and running for the first time. I spent a fair bit of time retro fitting a VDO tacho into the original dash cluster, and I have completely torn down the gauge to fit it and hence I could have damaged it but I would like to ask for some help in trying to diagnose whether or not I have damaged it. My setup is as follows:
- Tacho wired up as per the fitting instructions supplied. Sense wire to coil negative, 12V positive through ignition switch fused, ground to vehicle body
- Ignition system is a Bosch HEI electronic distributor out of an early Commodore with the large cap using a Bosch HEC716 coil
So when I first start the car, sitting at idle to tacho comes up, say 1000rpm. When I rev the engine in small increments, the tacho does not move. If I rev the engine in higher increments, the tacho begins to move. When I turn the ignition off, the tacho will stay at the last position it was in. I have read this is sort of normal and should reset to zero when the key is turned to ignition and back off again, so i did this and the tacho moves down to say 500rpm and thats it, it stays there. Now to make things even more complicated, when I disconnect the sense wire with ignition off, the tacho will come down to zero. My electrical knowledge is very limited but to be it seems that the tacho is not sensitive enough. Could this be the case or is there something else at play here?
Any thoughts or suggestions welcomed with open arms before I go off and buy a new gauge.
As a side note, I would also like to mention that I had an issue with the alternator regulator whereby I was seeing the dash light flash on and off so checked voltage across the battery whilst it was running and it read 15V using both digital and analogue multi-meter. So I believe the voltage regulator is stuffed (even though this was new!) and so the alternator is currently at the auto elec who rebuilt it for a full bench test. I don't think these two issues are related but just thought it was worthwhile noting.
Thanks!