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1989 Base Cluster Fu- ah Swap

5K views 29 replies 6 participants last post by  Thunderbird Pilot 89 
#1 ·
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/B01L0BTAX...olid=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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#2 ·
Damn nice Writeup!

I appreciate you attention to detail. :)
 
#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.
 
#5 ·
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
 
#9 ·
>:)>:)

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
 
#12 ·
#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.
 
#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.
 
#24 ·
Grrrrr! Well after a successful test drive I opened it up to roll the odo numbers forward to be accurate (this '96 car only had 26k miles on it). I also swapped in the new gear, the original was intact but the replacement is supposedly better plastic so why not put it in now. And now the odo doesn't work. I followed the tutorials exactly, made sure the gears all mesh together. If I roll the trip numbers by hand the gears turn, if I roll the gear by hand the numbers turn. Sounds like all should be good. I opened it up again to reinspect and still see nothing wrong, everything looks like it should.

I just put it back in the car to test again, and now it's popping the cluster fuse, repeatedly. I can't see anything wrong, and can't imagine what I could have done to screw up the odo. I figure my only option is to get another cluster and leave it alone, assuming I find one with a good gear.

I expected the harness adapters to be a potential problem, but they've worked perfectly.

Cluster **** :frown2:
 
#25 ·
Well I found why it was popping fuses, one of the solder joints on the adapter must have been rubbing on the dash frame and wore through the electrical tape. The solder joint is for start/run power and was shorting on ground. A few extra layers of tape sorted that. I also noticed this morning that the super glue on one of the adapter wires had come loose, allowing the wire to lift up and break the copper tape. This was the speed sensor wire, which I must assume now has been broken for several days because the speedo and odo both function now after fixing the wire. Now I just need to wire up the tach and oil gauge and this project will be done.

Cluster fuckin' A! :thumbsup:
 
#26 ·
Well let's catch up. After much frustration and many words of curse I managed to get the tach working, and it seems fine.

I decided to put off the oil pressure sender swap until I'm ready to do the 3G alternator upgrade, then I can remove all the brackets at once and throw two stones at that bird. So for now I figured I'd just run the stock switch and at least have the idiot light function, but there was no reading on the gauge. I ran a new wire, bypassing everything and ran it straight to the cluster connector. Here's the strange part: the gauge reads when I turn the key to run, but drops back to zero when it's started. The check gauges light also comes on when started, but remains off in run (which is why I'm sure it's being triggered by the oil gauge).

Any ideas what's going on here? It's just one wire so it can't be a polarity issue.
 
#27 ·
Which sender partnumber did you use?

There's two kinds, one is low to high, one is high to low resistance.

A 97 car and a mark 8 use the opposite sender as the other cars.
 
#29 · (Edited)
Since you started with a base cluster, it would have had an indicator light for critically low oil pressure. Your stock sender(switch) for a dummy bulb works opposite of the one used to modulate the fake analog gauge in the sport cluster. 1997s are the same way as the early base cluster since they too use a light instead of a gauge, the senders are likely even the same part number

When you turn the key to on before the engine starts you have 12v going through the circuit, the switch is closed with no pressure, pointing the needle straight up. When the engine turns over the switch opens due to oil pressure(which would shut off the dummy light in the base cluster), and with the analog cluster the gauge no longer has 12v going to it, making it read zero


Check gauges monitors the oil pressure signal, it’s an all encompassing warning dummy light, if it sees no oil pressure it will light, if it sees low fuel it will light, etc. Changing to the correct sport sender(switch) or true analog sender for the mod will solve this too.
 
#30 ·
OK, that makes sense now (I thought the dummy gauge used the same switch). Guess I'll just live with it until I do the alternator upgrade, and swap the sender as well.

Ya know, in the past year that I've been on this forum I've learned more about this car than I did during the prior 29 years of ownership. You guys rock :thumbsup:
 
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