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After 30 years of looking at my lame 3 gauge instrument cluster, it's time to upgrade. I obtained a sport cluster from a '93 Cougar, and the '89 and '93 EVTMs.

The '93 book has a very nice wiring chart, much more handy than the schematics.


The '89 book has no such chart, so I did some copy/pasting on the '93 scan to depict the '89 wiring. This made it so much easier to switch the wiring around.


Notice the red text. My car has no tach, therefore no wire for it. The number 1 slot in that connector is empty, so I'll insert the tach wire there when it's added.

Since this is my only car I can't have it undriveable for very long. So just in case something goes wrong with the rewiring I have to be able to swap back to the original cluster while I figure out the problem. I decided to make an adapter harness, just like you would use for an after market radio. I picked up an extra cluster from an '89 SC. It was pretty beat up and missing the speedo, so it was cheap.


I cut the harness connector sockets from the back of the SC cluster. Then I made new circuit traces with 1/8" copper foil tape.


Copper tape https://www.amazon.com/dp/B01L0BTAXA/?coliid=I1GBR5R2WHN4VO&colid=2EEWEMBS87FGW&psc=1&ref_=lv_ov_lig_dp_it

I tacked down the wires with super glue, to prevent the copper tape from being pulled up if the wires get tugged on. It also made soldering easier.


Then I soldered all the connections. Some wires had to be doubled up on one trace, and even triple on one.




Now it's test time, glad I studied! I removed the old cluster.


Plugged in my custom harness adapters.


And hooked up the new cluster.


Tach and oil don't work as they are not wired to anything yet, I assume that's why the "Check Gauges" light is on. Everything else seems to work though.

The gauge lighting also works.


Even the speedo and turn signals work, which I verified with a trip around the block. It was cool to drive with the new cluster, almost like a different car (with the same squeaks and rattles though). But I didn't want to go too far with a busted odometer gear, so I'll replace that tonight. And reset the numbers to match the old one while I'm in there.
 

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Damn nice Writeup!

I appreciate you attention to detail. :)
 

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Discussion Starter #3
Thanks! More to come as I continue. The harnesses already came in handy, as I swapped the original cluster back in after my test drive.
 

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Discussion Starter #4
I got the new odo gears in, no need to cover it as it's well documented. I also reset the numbers to match my old odo, also documented but the picture links are dead on that thread. I looked at it for a while, trying to figure out how it goes together, and I noticed that one end of the axle pin for the number wheels is retained by what looks like a tang nut. The end of the pin protrudes past the nut, so a regular screw driver won't work. I don't have the appropriate tool but I managed to get it started with a pair of pointy hook-nosed tweezers. A few turns got the nut clear of the pin so I could finish with a screw driver.

Here's the nut. It got nicked a bit by the tweezers but no real harm done.


Removing the nut frees the axle pin to wiggle a bit in the hole, and allowed it to be pulled away from the wheels just enough to turn them one at a time to reset them. So the "new" 75k odo now matches my 142k original.
 

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Removing the nut frees the axle pin to wiggle a bit in the hole, and allowed it to be pulled away from the wheels just enough to turn them one at a time to reset them. So the "new" 75k odo now matches my 142k original.
Just as a note to those with a bit more electronics around ...

These odometers/speedometers use 8,000 pulses per mile. You CAN fake it for a while (depends on how long you want to wait!) with a signal generator at about 5V to 8V output that generates square-ish waves, and a 12V power supply.

Simple math - 60Hz will give you 27MPH, 120Hz gives 54MPH, 240Hz gives 108MPH.

So at 240Hz, you can "cover" 108 miles in an hour. Need 10,800 miles? Run it for 100 hours. Since there's 168 hours in a week ... that's about 4 days of running.

Need 100,000 miles? Closer to 40 days, but still doable on a redo. All it takes is a bit of time.

(A LOT easier than on my eddy current speedo on the Dakota ... )

RwP
 

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Just as a note to those with a bit more electronics around ...

These odometers/speedometers use 8,000 pulses per mile. You CAN fake it for a while (depends on how long you want to wait!) with a signal generator at about 5V to 8V output that generates square-ish waves, and a 12V power supply.

Simple math - 60Hz will give you 27MPH, 120Hz gives 54MPH, 240Hz gives 108MPH.

So at 240Hz, you can "cover" 108 miles in an hour. Need 10,800 miles? Run it for 100 hours. Since there's 168 hours in a week ... that's about 4 days of running.

Need 100,000 miles? Closer to 40 days, but still doable on a redo. All it takes is a bit of time.

(A LOT easier than on my eddy current speedo on the Dakota ... )

RwP
The new gear will break by the time it gets there, nerd :tongue:
 

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The new gear will break by the time it gets there, nerd :tongue:
Seriously, I doubt that unless it's a totally crap formulation.

What gets the originals is age and heat; you run 100K on a bench at 108MPH (or even at 132!) then it won't be AGE killing it, and most of them will last fine for that time.

Although, I could be wrong ...

But still, strangely enough, THIS is legal; adjusting the odometer by hand, not so much. :tongue: :nerd:

RwP
 

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It would take a crack investigator to figure out whether I used a signal generator to advance the miles to match over the course of several days or pulled the pin to advance them by hand over the course of several minutes. “You’ll never catch me copper!”.
>:)>:)

You're right of course.

But I'm lazy, fat fingered, and have been making electrons do my wishes for about 50 years now ...

RwP
 

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Discussion Starter #10
Just as a note to those with a bit more electronics around ...

These odometers/speedometers use 8,000 pulses per mile. You CAN fake it for a while (depends on how long you want to wait!) with a signal generator at about 5V to 8V output that generates square-ish waves, and a 12V power supply.

Simple math - 60Hz will give you 27MPH, 120Hz gives 54MPH, 240Hz gives 108MPH.

So at 240Hz, you can "cover" 108 miles in an hour. Need 10,800 miles? Run it for 100 hours. Since there's 168 hours in a week ... that's about 4 days of running.

Need 100,000 miles? Closer to 40 days, but still doable on a redo. All it takes is a bit of time.

(A LOT easier than on my eddy current speedo on the Dakota ... )

RwP
I figured something like that was possible, but my method took less than 10 minutes. Not counting the 30 or so I spent looking it over.

This guy's method is also too long. https://youtu.be/TmLQTJ7aRLs
 

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Discussion Starter #11


Took a second test drive and the odometer still doesn't work. I need to find out if maybe the gears are not seated right, or if it's an electrical issue. I tested each connection after soldering the harnesses and they all worked.
 

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Just as a note to those with a bit more electronics around ...

These odometers/speedometers use 8,000 pulses per mile. You CAN fake it for a while (depends on how long you want to wait!) with a signal generator at about 5V to 8V output that generates square-ish waves, and a 12V power supply.

Simple math - 60Hz will give you 27MPH, 120Hz gives 54MPH, 240Hz gives 108MPH.

So at 240Hz, you can "cover" 108 miles in an hour. Need 10,800 miles? Run it for 100 hours. Since there's 168 hours in a week ... that's about 4 days of running.

Need 100,000 miles? Closer to 40 days, but still doable on a redo. All it takes is a bit of time.

(A LOT easier than on my eddy current speedo on the Dakota ... )

RwP
Did the same to dial in the speedometers accuracy after replacing the gears.

I have to give credit to my dad for helping me set it up.... I am no EE; but he is
 

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Discussion Starter #15
Well I opened it up again, and everything looks to be in order. The new gears are seated properly, and they spin if I move the number wheels by hand. I just did another test drive, still no odo and now the speedo is also out. When I start the car the speedo jumps to 80 and stays there, and just quivers a bit while driving (it worked fine the first two test drives). The original still functions so the car's wiring is OK, and a test of the harness adapters show the connections still conduct properly. Looks like I may have a bad speedo, and the few separate ones I see available cost more than twice what I paid for this whole cluster.
 

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Discussion Starter #16
I picked up a new cluster at the pick-a-part today, from a '96 for $35. I don't have a '96 EVTM, is there any difference in the wiring between '93 and '96? If so I can just swap the speedo, but the '96 is in overall better condition, not even a scratch on the clear window.
 

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Discussion Starter #18
The pinouts are slightly different IIRC but i’ll double check. I know for sure the 91-92 sport clusters are different. the circuit on the back changed but everything else in the cluster interchanges
That's what I thought, but thanks for the confirmation. It just occurred to me that I could determine the wire positions by color, assuming the color/circuit relationship is the same?
 

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Discussion Starter #20 (Edited)
Hmm, quite a few differences. Some circuit numbers and some colors are different. I think I'll keep the '93 housing and wiring and just swap in the '96 gauges, after the effort to make the adapter harness I'd rather not have to redo it.

*EDIT* Actually the smaller connector, that goes behind the speedo, is identical except for one wire color change. The circuit functions and positions are the same. I could cut and splice the larger one to work without a full redo. Thanks again.

*EDIT 2* On closer comparison the larger connector is also mostly identical. Some circuit numbers are changed, and a few wire colors, but the functions and positions are the same except for one or two. This should be an easy swap.

*EDIT 3* The '96 doesn't even have a Door Ajar light! I'll leave the wiring as is there and swap in the graphic from the '93.
 
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