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nerlins
11-18-2014, 02:07 AM
I'm just curious if anyone knows of an aftermarket tach that would 'fit' reasonably well in the stock combination meter housing. Mine died. The car runs perfectly fine, but I never know what the rpm speed is.

I'm not against trimming, JB weld, etc., to get it to 'fit'. I'm just not going to waste my time with a junk yard part, and new old-stock is $400. I'm fine with a $100 (max) tach I can splice wires to the connector with.

Thank you for any info.

nerlins
11-18-2014, 02:15 AM
Hell. I just thought of this question. Where and what is the sensor to actually send the signal to the PCM, for the tach????

Nitro_Alltrac
11-18-2014, 03:15 AM
Pretty sure the tach is fed from the igniter. I was just looking into that a few weeks ago.

Tach is basically the same size as the speedo. I've taken some measurements of that before. The speedo is 4 3/8" diameter and is an inch and a half deep.

nerlins
11-22-2014, 07:45 PM
If ignitor is what you are calling the distributor, then I think I'm on the right track. I've searched the electrical diagrams, and have found it's a black wire going from the dizzy to tach plug. I'm gonna take mine out, and see if the dial is easily replaced. Found a few assemblies on ebay. I'll take a gamble, and switch the dials, since I want to keep my actual mileage reading.

Thanks.

VavAlephVav
11-23-2014, 03:40 AM
I know on a 6th gen the tach signal comes from the igniter (little silver box on the firewall), in the service manual it describes how to hook up an extra tach to use while working on it. I'm guessing the 5th gen should be the same but not certain.

crymson
11-23-2014, 07:04 AM
yes, you can get the tach signal off the igniter (it's the silver box on the drivers side against the firewall) on a 5th gen. I've done it on a GTS for remote start.

You can also get it off one of the wires in the check connector, but I could never figure out which one.

david in germany
11-23-2014, 11:49 AM
Why not pull the combination cluster from another Celica from a salvage yard and reinstall? It is only a 10-15 minute job.. Adding and aftermarket tach is going to add hours onto the install time.


Sent from my iPad using Tapatalk HD

klapa
11-23-2014, 02:11 PM
I had the same issue with my ST, though the tach slowly degraded over time. It would read lower than normal in cold weather then OK when warm at first, then gradually got worse till it died.

I had another cluster so just removed the tach from that one.

This was probably caused by the electrolytic capacitors on the tach PCB, as later a friend with a 1993 MR2 that had the same problem - both speedo and tach were completely inop. and he had gotten a ticket and needed them fixed before he was to go to court. I changed the capacitors for him and it solved the problem on both. I can get you the part numbers of the caps if you like - there is a good video on youtube about it. You would need good soldering equipment to do the job.

Else I or perhaps many others here have a few old clusters you could use to change the tach.

The tach itself is just an electric motor. A signal from a coil in the dizzy goes to the ECU and the ECU uses this to send a voltage that drives the tach.

For an MR2 the speedo is the same - ST has mechanical speedo.

klapa
11-23-2014, 03:04 PM
Here is some info from when I repaired the MR2 gauges:

Youtube link:

https://www.youtube.com/watch?v=G7qzfjwzT14

The video doesn't use parts that are an exact fit for the originals. After I had replaced the parts, I measured them and came up with exact replacement parts:

Manf. Manf. P/N Description Digikey P/N Size
Nichicon UMA1E101MDD1TP CAP ALUM 100UF 25V 20% RADIAL 2000Hr.@85C 493-10432-ND 8mmDx7mmH - 3.5mm lead pitch
Nichicon UMA1V220MDD CAP ALUM 22UF 35V 20% RADIAL 2000Hr.@85C 493-5961-ND 6.3mmDx6mmH - 2.5mm lead pitch
Nichicon UPW1V6R8MDD CAP ALUM 6.8UF 35V 20% RADIAL 2000Hr.@105C 493-1848-ND 4mmDx7mmH - 1.5mm pitch
Nichicon UPW1E100MDD6 CAP ALUM 10UF 25V 20% RADIAL 2000Hr.@105C 493-1810-ND 4mmDx7mmH - 1.5mm pitch

Remember - these are parts for a 1993 MR2 gauges, yet I would be surprised if the electronics in other gauges are much different.

I have pics if anybody wants them.

93celicaconv
11-28-2014, 02:54 PM
Yes, I would highly recommend getting a cluster from a salvage yard, then swapping the tachs out. I've done several gauge swaps between clusters before, quite easy to open these clusters up and swap gauges. Not guaranteeing salvage tachs will always work, but there is a high chance they will. I have several old clusters, would be willing to let one go, but I would not have tested the tach so could not guarantee what I have works, and prefer not to remove a cluster in one I have to check. If you don't want to get an entire cluster from a salvage yard (if they cost a fair amount), you can always disassemble in the pick 'n pull and just get the tach.

nerlins
12-09-2014, 01:20 PM
Hey guys, thanks for all the info (and the link, Klapa). I hadn't had time to log on.

I just found a few clusters on ebay around $50, so I'm gonna buy one there. I'll look for this little silver box; the manual says the signal comes off the dizzy, but maybe it's transferred to the box first? My main concern is that I am getting proper signal/ voltage to the old one, and not that it's just a worn out tach.

BTW, just got a new hinge for the trunk off ToyotaPartsOverstock. Feels great to be able to use meh trunk again :-)