Ok, This is what I did in my Hilux with the exact same conversion. I have had this working for 10 years in my car.
I just happen to have the tacho out at the moment, so I took pictures.
So you need :
1x bc337 transistor
1 1k resistor (brown black red)
1 10k resistor (brown black orange)
Get the tacho out 3 screws on rear of instrument panel. Remove the diode marked d1 on the board. I have circled the underside of it on the main board. Just lift 1 leg. The other pic is the diode with leg lifted. Now get the transistor and solder the resistors like the picture. Solder the wires to the correct places in the picture. Resistors don't care which way around. Transistor
does.
The tacho wire from your commodore loom connects to the signal input terminal with the 10k resistor. I got an extra pin and fitted it in the Hilux plug at the back of the instrument panel, so it just unplugs like normal. You can trace it back from the signal input terminal. Follow the track back to the correct pinhole in Hilux plug.
OZ38 wrote:Gidday,
Is there some sort of test device/equipment that could be hooked up to this wire so I can test if the original Hilux tacho is still working ?
Auto Sparkies ?
From memory, (its been a while) the Commodore tacho output is 5v square wave and the Hilux needs 12 volt square wave so this circuit does that for you. If you have the tach out of the car you could hook up 12 v, ground and signal on another car that is a bit older that has points or distributor or a single coil. It might read wrong but will show the tach is working. The signal wire is the one between the coil negative and the distributor.
Also there is a pot (potentiometer)on the board, you can tweak this to calibrate the tacho once it is working. The white round part .
I also connected the check engine light and pwr mode lights in the Hilux dash. They were already there just not connected. I have a switch on the dash which does the paper clip in the diagnostic plug, so it's really easy to check the fault codes and flashes the dash light. There is a cruise light ( one day), OD off and a back door light. Not sure what I could use the back door light for. Maybe for when the missus is a bit randy?
- tacho pcb.jpg (336.48 KiB) Viewed 6887 times