How to test a Hilux 4wd Tacho ?

Wiring diagrams and questions
User avatar
Posts: 1426
Joined: Tue Apr 26, 2011 9:52 pm

Re: How to test a Hilux 4wd Tacho ?

Postby psyolent » Tue Sep 20, 2016 6:39 am

remove the tach from the ute, before you do this man.
this would be bench testing the tach.

yes ; even if its a different rpm, still shows you its reacting to the waves its seeing.

It wasn't so much the voltage but rather the frequency of which I was fairly sure was 50Hz instead of the US 60Hz.

which might not matter too much ; as the wave depending on how the DC battery charger rectifies it will be slightly less in its peaks at 50Hz :)
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VX2 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.

User avatar
Posts: 57
Joined: Mon Aug 10, 2009 7:57 pm
Location: Adelaide SA

Re: How to test a Hilux 4wd Tacho ?

Postby gibbo » Wed Oct 12, 2016 1:55 pm

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? :punk:
tacho pcb.jpg
tacho pcb.jpg (336.48 KiB) Viewed 1405 times
tacho diode.jpg
pot.jpg
dash rear.jpg
Last edited by gibbo on Thu Oct 13, 2016 7:20 am, edited 7 times in total.

User avatar
Posts: 1925
Joined: Fri Mar 14, 2014 8:37 pm
Location: Bacchus Marsh, Vic

Re: How to test a Hilux 4wd Tacho ?

Postby Biggvl » Wed Oct 12, 2016 2:19 pm

Hey, thanks for posting :thumbup:
According to chemistry, alcohol is a solution...

User avatar
Posts: 1426
Joined: Tue Apr 26, 2011 9:52 pm

Re: How to test a Hilux 4wd Tacho ?

Postby psyolent » Wed Oct 12, 2016 6:26 pm

gibbo - thats awesome mate and very very useful - thanks heaps!
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VX2 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.

User avatar
Posts: 57
Joined: Mon Aug 10, 2009 7:57 pm
Location: Adelaide SA

Re: How to test a Hilux 4wd Tacho ?

Postby gibbo » Wed Oct 12, 2016 8:10 pm

Glad to help. Here is the diagram. This could be used for any tacho from the Commodore tacho signal.
tacho diag lables.jpg
tacho diag lables.jpg (21.93 KiB) Viewed 1406 times
BC337 legs.gif
BC337 legs.gif (10.64 KiB) Viewed 1408 times

Posts: 218
Joined: Wed Jul 01, 2009 7:18 pm
Location: Jurien Bay, W.A.

Re: How to test a Hilux 4wd Tacho ?

Postby OZ38 » Fri Oct 21, 2016 11:52 am

Thank you for your reply there gibbo. I was hoping there was an easy test while the dash was still in the Hilux, as it already has one of these early type Marks 4wd adapter convertor boxes wired into between the VS V6 ecotec & the hilux dash. I will try a bit harder to understand what you have done, but I have no experience with resistors & transistors or soldering then together etc. I would really like to get a good soldering setup like I see you have in the background of one of the pics. (not a electronic kind of guy). I gather your set up doesn't need the convertor box / board to change the V6 tacho signal to what the Hilux is needing ? Round wave/ square wave/ 12v or 5v it a lot to learn at 55 lol.

User avatar
Posts: 57
Joined: Mon Aug 10, 2009 7:57 pm
Location: Adelaide SA

Re: How to test a Hilux 4wd Tacho ?

Postby gibbo » Fri Oct 21, 2016 1:56 pm

No I don't need a converter box this works straight off the commodore wiring loom (comm tach sig in). You don't need to understand it just copy the picture!
You probably don't want one of those soldering irons, it about $700. You could get away with one from jaycar for $20 . Instead of soldering you could use crimp connectors or terminal strip maybe.
To test it in the car you could extend the wire from the tacho really long to reach another car next to yours, to the coil wire. Then put jumper leads between the cars as normal and tacho will work with the other car running. A bit fiddly but if you haven't got the dash out......
This test is without your adapter box , just the tacho. Dont forget to turn the ignition on in the Hilux. Dont start it , just ignition on.

Maybe I can help with the converter box too?

Posts: 218
Joined: Wed Jul 01, 2009 7:18 pm
Location: Jurien Bay, W.A.

Re: How to test a Hilux 4wd Tacho ?

Postby OZ38 » Fri Oct 21, 2016 5:39 pm

gibbo wrote:No I don't need a converter box this works straight off the commodore wiring loom (comm tach sig in). You don't need to understand it just copy the picture!
You probably don't want one of those soldering irons, it about $700. You could get away with one from jaycar for $20 . Instead of soldering you could use crimp connectors or terminal strip maybe.
To test it in the car you could extend the wire from the tacho really long to reach another car next to yours, to the coil wire. Then put jumper leads between the cars as normal and tacho will work with the other car running. A bit fiddly but if you haven't got the dash out......
This test is without your adapter box , just the tacho. Dont forget to turn the ignition on in the Hilux. Dont start it , just ignition on.

Maybe I can help with the converter box too?

Thanks mate. Just thinking I have a mate with a 5 litre SLR Torana which runs the single coil set up. Might be able to do like you suggest & see if his signal will move the Hilux tacho.
As for the $700 soldering iron, I would be more likely to buy that than a $20 jaycar set up. I have this thing about buying only quality when it comes to tools etc.

Cheers

User avatar
Posts: 57
Joined: Mon Aug 10, 2009 7:57 pm
Location: Adelaide SA

Re: How to test a Hilux 4wd Tacho ?

Postby gibbo » Sun Oct 21, 2018 9:55 am

I am adding this as it might help someone looking for a tacho interface. These modules will do the same thing without having to make it up yourself.

https://www.justraceparts.com.au/jrp-ta ... al-adapter

https://www.justraceparts.com.au/jrp-un ... ch-adapter

Previous

Return to Wiring

Who is online

Users browsing this forum: No registered users and 2 guests