Trouble shooting Safari Rev counter

[Craydiver]

88 GQ td42NA swb Safari
Rev counter not working when I purchased this vehicle last yr.
Every other instrument/gauge works fine.
Have pdf manual but does not actually tell me much about sensor output, resistance checks or other. extensive search on this forum (300+threads) hasn't actually told me much more than the rev counter itself has 12v feed.
Just installed UHF and discovered that car radio was feeding off 12v converter which I located by passenger feet, hence I assume 12v converter is working fine - it was outputting 12v and new UHF works fine looping off stereo.
Can someone tell me:
the wires to the sensor on front of motor - should I expect voltage,(ign on), which coloured wire?
Or ohm check.?
With motor running is there output from the sensor you can measure?
Colour of wire that feeds the tacho itself that should carry 12v?

thanks

[quick6]

I had the same problem. Mine was going when I bought it but stopped soon after, if you hit the top of the dash it would sometimes flicker into life for a moment. My online research led me to believe that dry joints on the circuit board are often at fault so I went over the lot with a soldering iron and it has been good since. Might be worth a try.

[Ashohman]

if you hit the top of the dash it would sometimes flicker into life for a moment. My online research led me to believe that dry joints on the circuit board

Ha-ha DRY joints? hmmm wouldn't want them to be wet... If it doesn't work hit it you reckon... and if that doesn't work?....

what's that?

get a bigger hammer

[Gren]

Hey man, I don't have an answer for how to test for faults with the tacho but I do have a spare cluster that I know the tacho itself works- you're welcome to come plug it in to see if it works.
Ahh that is if you have a cluster with the white markings on it not the yellow ones. (Different plugs)

[nzlux]

I have had none working rev counters in both my pajero and hilux, both responded to the tap the dash, I never resorted to using a hammer. Both were caused by dry solder joint on the circuit board, resolder and the rev counters worked.

[Craydiver]

Hey man, I don't have an answer for how to test for faults with the tacho but I do have a spare cluster that I know the tacho itself works- you're welcome to come plug it in to see if it works.
Ahh that is if you have a cluster with the white markings on it not the yellow ones. (Different plugs)

thanks - ill try the tap and dry solder checks first, if they don't work I may take you up on the offer, once I check if it has white marking.
are you Auckland?

[buddrick]

Can some one put up a pick of the solder joins that they re soldered to get the rev counter going again???

[quick6]

Can't take a photo as I will be using my truck in ten minutes. If you look on the back of the cluster behind the rev counter you will find the screws to remove it, just follow your nose. Once the unit is seperate from the rest of the cluster you will see the circuit board, no discrimination here I soldered the lot. You will need a decent soldering iron and a steady hand.

[Gren]

Yeah man just in Onehunga.