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JimX

How To Fix Tacho, R33 (maybe)

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I had an intermittent tacho, which gradually declined into a full non-working tacho for the past month or so. After finally getting the time to rip the cluster out again and doing what I described below, the tacho started working straight away. I'm not 100% sure this is what fixed it but I'm fairly confident it has. This procedure may apply to different cars with similar setups, just check the correct pins and plugs etc. It's fairly straightforward.

Diagnosis:

What I found is the metal tag on the black loom plug that goes into the tacho (the lower one on the side with 2 plugs on it, the right side as you look forwards) was sitting a bit lower than the other 2 on either side of it. Since this plugs into a socket which has a stiff plastic sheet for holding the connectors, I imagine that the 2 higher tags were lifting the sheet up and out of the way to make the contact with the tacho signal wire dodgy at best, and depending on how the car flexes and moves as you drive, possibly breaking all contact.

Procedure:

1. Remove the instrument cluster (not covered in this DIY, should be somewhere else in this forum)

2. Find the plug that goes into the tacho. On mine (R33 GTR) it's the lower plug on the right side looking forwards.

3. Find the tacho signal wire pin/tag on the loom plug. On mine, it's the pin that goes into something labelled "TAM" in the cluster socket, which is a track that goes directly into a bolt that holds the tacho on. The signal pin on mine sits between 2 other metal tags in the only group of 3 tags on the black plug.

4. Clean the metal tags and the copper track contacts with some electrical contact cleaner, plus maybe rub clean with something non-abrasive.

5. With a pair of jeweler's screwdrivers or similar (safety pins should be fine), very gently prise up the metal tag on either side of the middle, where the bend in the metal is, to make it flush with the 2 on either side of it. Try to keep the pressure uniform on both sides to avoid over stressing the metal.

6. Plug the dash back in and test it before reassembling everything, to make sure it works, or that you haven't made things worse.

7. If it's all now working, reassemble everything and have a celebrationary beer for having saved yourself a couple of hundred for a new tacho/dash cluster.

7a. If it's still not working, at least now you have ruled your loom/plug as a problem, and can more easily send your dash out for repair or replace it with another one.

One more amateur diagnosis check:

When I had everything apart, I checked the resistance on the tacho signal wire for the hell of it. The resistance went quickly from some high value to open circuit, each time I tested it and swapped to the earth next to it and back again. Since my tacho now works, I imagine this reading is indicative of a properly working tacho signal wire. If you have an earth here instead, or it doesn't skip from high resistance to open circuit, or some uniform low resistance value, then you might have a problem with your signal wire. I'm not an expert here, so this is just speculation and something for you to try while it's all apart.

NOTE: DON'T DO THIS WITH THE IGNITION ON!!! I always check voltages before resistance, to make sure I'm not buzzing out a 12V live feed.

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Just woke up to this problem and right when someone was test driving my car!

Will check the tacho tomorrow.

Thanks for the thread in advance.

Rusty

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My searches are not going too well.

Mine decided to flip past 9K after some spirited driving last week. It came back alive, then died.. then fluttered all over the place.

Since then, I was able to get it working perfectly by pressing on the top-right section of the cluster while driving.. until I hit a bump and it went haywire again.

So on the weekend I pulled it out and did pretty much what is described here. I filed the plug (all contacts) so that they were shiny, then got contact cleaner and went over all the tracks in the sockets on the back. Initially I had it loose and started the car, fiddled with the wires and couldn't make it play up.

After the cleaning, I put it back in (not screwed in) and turned the car on and off about 5 times. I revved it past 5K (the point at which it used to fall down to 9+) and it was fine. Put it back in, put the dash all back together, tested in the driveway while pushing all over the cluster and banging the dash... it was fine.

Went for a drive, and it failed. =-/

I'm at a loss, and I can't find any guide on how to replace the tacho with another from a used cluster, but I assume it's possible? Help on the topic would be appreciated!

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My tacho hasn't worked for awhile now. Everytime I pull it out of the dash to do something it seems to fix it for a few days or weeks, then eventually it dies again and sometimes comes back by itself, and sometimes (most of the time in my last few attempts) whatever I do doesn't fix it at all and it stays dead indefinitely. It used to start working by itself more often when the car's been sitting in really hot or cold weather for a long time (usually hot) but again, not lately. In extreme weather conditions I'm guessing a loose contact somewhere is expanding or contracting enough to make a better contact with something else in there, but where that is exactly I am not longer sure. It could the plug contact in the dash or it could be a dry joint or failing component in the tacho itself.

Does anyone know how to test a tacho with some cheap parts or a Jaycar kit? I might head down to Jaycar on the weekend and see what they have, they must have some sort of 12v variable pulse generator I can rig up and pretend it's an engine. Gravedigging this thread has inspired me to suddenly care more about my inability to read revs :P

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Hey Guys,

I've just recently fixed this problem in my 33 GTST. My tacho also liked to pretend I was hitting redline and just was gay all the time. Here's how I fixed it...

Step 1) Go buy a second hand cluster. Doesn't matter if it's auto/man S1/2

Step 2) Pull out your current cluster from the car. (check tutorials for dash removal)

Step 3) find a small Flat head and Phillips head screwdrivers.

Step 4) Prize the black cover from the white backing of dash (there's 5 clips - 4 along the top, 1 on the bottom)

Step 5) Flip the cluster and undo the 3 screws holding the tachometer in place

Step 6) undo the 2 tiny screws on the front of the Tachometer (WARNING: This will make the Tacho loose DON'T Drop it!!)

Step 7) Repeat above to current cluster

Step 8) Swap tachometer's between the two clusters

Step 9) Put your cluster back together, reinstall into dash. Fire it up and see what happens!!!

Step 10) Hit redline to attain success - Optional :D

Step 11) Throw out old dash bits or reassemble and sell it back to the wreckers for a profit ;)

This fixed mine instantly. I've had no problems now for a few months. All up it cost me $80

Cheers Sparks

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Hey Guys,

I've just recently fixed this problem in my 33 GTST. My tacho also liked to pretend I was hitting redline and just was gay all the time. Here's how I fixed it...

Step 1) Go buy a second hand cluster. Doesn't matter if it's auto/man S1/2

Step 2) Pull out your current cluster from the car. (check tutorials for dash removal)

Step 3) find a small Flat head and Phillips head screwdrivers.

Step 4) Prize the black cover from the white backing of dash (there's 5 clips - 4 along the top, 1 on the bottom)

Step 5) Flip the cluster and undo the 3 screws holding the tachometer in place

Step 6) undo the 2 tiny screws on the front of the Tachometer (WARNING: This will make the Tacho loose DON'T Drop it!!)

Step 7) Repeat above to current cluster

Step 8) Swap tachometer's between the two clusters

Step 9) Put your cluster back together, reinstall into dash. Fire it up and see what happens!!!

Step 10) Hit redline to attain success - Optional :D

Step 11) Throw out old dash bits or reassemble and sell it back to the wreckers for a profit :bunny:

This fixed mine instantly. I've had no problems now for a few months. All up it cost me $80

Cheers Sparks

This is exactly the same problem that I am currently having with my tacho. It seems to calm down on hot days for me. It’s driving me nuts! Thanks for the info. :devil:

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Hey Guys,

I've just recently fixed this problem in my 33 GTST. My tacho also liked to pretend I was hitting redline and just was gay all the time. Here's how I fixed it...

Step 1) Go buy a second hand cluster. Doesn't matter if it's auto/man S1/2

Step 2) Pull out your current cluster from the car. (check tutorials for dash removal)

Step 3) find a small Flat head and Phillips head screwdrivers.

Step 4) Prize the black cover from the white backing of dash (there's 5 clips - 4 along the top, 1 on the bottom)

Step 5) Flip the cluster and undo the 3 screws holding the tachometer in place

Step 6) undo the 2 tiny screws on the front of the Tachometer (WARNING: This will make the Tacho loose DON'T Drop it!!)

Step 7) Repeat above to current cluster

Step 8) Swap tachometer's between the two clusters

Step 9) Put your cluster back together, reinstall into dash. Fire it up and see what happens!!!

Step 10) Hit redline to attain success - Optional :)

Step 11) Throw out old dash bits or reassemble and sell it back to the wreckers for a profit ;)

This fixed mine instantly. I've had no problems now for a few months. All up it cost me $80

Cheers Sparks

This is the path i've been looking into going down. I've priced it all up, and i'm about to order one.

Pity there isn't some common fault that is easy to fix with some solder.

Thanks for the info!

-Steve

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i've got the same problem on my R33 GTR,it works sometimes,usually hangs around 1k rpm mark,and sometimes moves around the range,only seen it go up to 5k rpm so far and then it shot down to 0

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Well took my cluster apart today (R33 GTST) and looked to see if i could find any issues as my cluster is messing up. All contacts were good and continuous (thank god for multimeter's) I went to undo the three screws the from the back of the cluster which hold the tacho in and noticed that one of the screws was different and severely corroded.

I cleaned the screw and tried to clean the corrosion out of the screw slot and after stating the car it seemed a little better. Maybe tomorrow (if its a clear day) ill get a new screw and some contact cleaner to try and clear the terminal on the tacho.

Hopefully this is the problem and will fix the dodgy tacho.

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I have a bung tacho as well. Am used to it by now, but in a way am bummed about it. Clearly some design or manufacturing fault at play. Once in a blue moon it actually works, but then it goes back to it's "seeking" mode and will be sitting at 9000rpm when I'm actually at a stop light lol.

Also my speedo has started acting strange. Sometimes it won't work at all and I'll have to whack the top of the dash cluster. With enough whacks it starts working good again.

Am thinking I'll need to purchase some contact cleaner to try and clean both the gauges. Any one know a good brand of stuff to use?

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Am thinking I'll need to purchase some contact cleaner to try and clean both the gauges. Any one know a good brand of stuff to use?

Buy some CRC contact cleaner. We use this at work and it does the job well.

Also, i plan on doing a bit more fault finding on the tacho/speedo issues. It looks like the screws holding in the tacho act as voltage/ground/signal terminals.

Im thinking if using OFHC copper wire with nylon bolts to get a clean signal to the tacho (one of the bolts is pretty corroded)

When i get this done ill post up the results.

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Look forward to seeing how things go Matt. My tacho worked fine when I first bought the car. Went on holidays overseas for 3 weeks and the car wasn't driven. Was also last winter too, so I'm sure some days it god coldish. Got picked up at the airport in my car, and when I was driving it home realised in shock I was doing "9000rpm" when I wasn't.

All I can conclude is the car was sitting for awhile in coldish weather. Since then it's never worked properly. But from time if I go over a bump, or tap the dash screen enough times, it will sync back up and work. But usually not for long. It'll then just keep climbing and climbing into the revs.

Oh, one thing too, is after I first got my car, and auto electrician replaced the "D" for Drive bulb in my dash cluster. Made a right mess too, scratching all kinds of plastic, but I'm pretty sure he took the tacho gauge out at the time. So it's quite possible it was never put back properly, or he damaged something.

Anyway, there's got to be a fix and I was thinking of taking mine apart, and giving it a spray. Then if that didn't fix anything, putting the soldering iron on anything that looks dry etc. Maybe just reheating something and letting the solder reset could fix things.

It's clearing a fault with this model of car, so there's got to be a fix somewhere. I've got a link to an UK skyline forum where some guy is talking about resistors and replacing x y z. Will dig it up and maybe it'll make sense to someone here as I didn't understand it.

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I managed to fix my tacho which was bouncing around between 4000RPM and 9000RPM. I will see if I can dig up the photos I took and post a HOWTO thread in this section over the weekend (note that this is only a fix for the "over 9000" problem, a non-working tacho is most likely not making contact with the loom plug that runs behind the cluster).

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I managed to fix my tacho which was bouncing around between 4000RPM and 9000RPM. I will see if I can dig up the photos I took and post a HOWTO thread in this section over the weekend (note that this is only a fix for the "over 9000" problem, a non-working tacho is most likely not making contact with the loom plug that runs behind the cluster).

That would be awesome to see. Any guides and tips on how to fix something with the tacho can help us all with our own issues.

I found the link to the UK Skyline forum about trying to repair a dodgy tacho. http://www.skylineowners.com/forum/showthread.php?t=56319

After fitting a replacement rev counter and that going 'mad' very shortly afterwards I decided to find out how to fix the problem once and for all.

Here's what to do if your rev counter is faulty...

Remove the dash.

Open the dash and remove the rev counter part, 3 screws from the back.

To prevent damage to the neddle etc. remove the printed circuit board from the neddle come x/y motor assy. this is 2 screws and the 4 solder pads that need desoldering.

The heart of the rev counter is a AN8352UBK i.c. that is a 'charge-pump' (frequency to voltage converter) and x/y output device in a single i.c.

This i.c. has a slightly smaller than 'normal' pin-pitch, it appears Nissan left to much 'solder-resist' on the p.c.b. around the holes through the board for it's legs to go through, I strongly recomend desoldering this i.c. completely and then cleaning the solder-resist back around where the pins exit, then re-fit the i.c. and resolder carefully, remember to use ESD precautions at all times.

It's not like 'normal' dry joints, the failiure is NOT visable there just is not enough copper p.c.b track for the solder to make a perfect joint, once the green solder resist is cleaned away it is fine.

That should now work!?

As a precation I changed the capacitors C2 and C5, (both 1mfd) for new ones, and lowered C7 from 2.2mfd to 1mfd for a slightly faster response on the neddle.

I calibrated mine and for your info 6000rpm=100rps x 6 cycl.= 600Hz should be linier as in 300Hz = 3000rpm average between the two points for best accuracy.

There is a variable resistor R1 on the board to do the calibration.

I hope you find this usefull, and even make it a 'sticky'

I am not a trader but if you need help PM me.

Regards,

Andy.

It sounds a little complicated, so I'll leave this as a last resort and try just cleaning the contacts and seeing if that helps things.

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Step 10) Hit redline to attain success - Optional :)

lmao- winner!

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Hey everyone,

Just helped jez NF to fit 666DAN's LEDs into his R33...

And now his RPM meter isn't moving ... what could have happened?

Most likely just a loose connection?

Cheers

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