Tach Conversion on a base 69 question…

Cougar Community Classic Cougar Maintenance Restoration and Repair
1

Hi all….

So I ripped out my dash for no reason…. So I might as well do the “While I’m at it” opportunity.

My cluster lights were terrible!

I have wanted to to do the LED conversion from WCCC, but I hadn’t organized myself… I am too impatient for a US order so hit Amazon.Au and saw a set for 12 bucks, they looked funky and complex… I also saw a simple looking set for 6 bucks! (Australian dollars no less)…

So as they say in the classics ….Y porque no los dos!

Lucky I did, but first the backstory…

My dash lights were dim to non existent, except for the bright green tach

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The bulbs turned up after two sleeps, the funky exxy $12 ones were too big, the cheap $6 ones were the same size as originals

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So I swapped these in, I first tried without wiring in the tach…

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What the? Blue cluster…. I thought it was green!

But when I plug the tach in, the green shines through

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If I post a closeup of the tach PCB and the wires, has anyone seen one of these before? Which wire to clip to kill the tach light?

If I had done it, I would have gone straight to a Rocketman classic tach… but a previous owner did it, and now it’s too far gone.

But the green backlight needs to go.

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I am hoping someone might recognize this arrangement and tell me which color wire to clip.

2

Your dash looks just like mine-base gauges with 6k XR7 tach! I’ve got the Rocketman tach on-hand for replacement.

3

Interesting, to say the least. Two things that may help you in changing the LED colors. One is that manual switch above the number T13251R stenciled on the PCB. What does it do ( color selection ) ? And secondly the recessed grey adjustment ( in the blue square ) ‘wheel’ next to the pin plug - what is it for ? Is it the intensity for the lighting of the LED’s ? If neither of these have anything to do with the LED color selection, then make some short connector wires from the pins on the PCB, and you should be able to ( a process of elimination ) unplug one wire at a time from the white molex connector to determine which one governs the green LED lights.
BTW, the blue color isn’t that far off the original Ford blue ‘diffuser’ color.

4

Original Ford dash lights look green because the incandescent bulbs produce a yellow light that is filtered through a blue diffuser to create green light. Use your multi meter to find the power lead that is going on and off with the light switch.

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I wouldn’t mess with the switch or potentiometer.
The switch is likely a cylinder count setting (4, 6, 8) and the pot is probably the range setting (where 6000 RPM is on the Cougar’s 250° dial).

6

Yes, I did not mess with the settings. Just got around to it late at night tonight.

I dug up an old motherboard, nipped off a couple of the prongs those ribbon cables plug on to, poked them into the wiring loom side plug thingie that feeds the tach. Figured black was earth, got a voltage on the white wire, nipped the white wire (and put some heat shrink over the nipped ends to ensure no stray circuit)…

Plugged the tach wires and cluster loom back in …. Gas tank read empty (was full) gauges all blue though… pulled it back out turned the oil and alternator lights back to incandescent , faffed with the flimsy printed circuit board for an hour…. Put the cluster back in the car… haven’t put the crash pad back in, I want to check the speedo works because I had a hard time getting cable back on, and the temp gauge (it is cold - needle doesn’t move) I will check tomorrow before I close it all up.

Thanks for all advice!

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The dish of the base gauges catches slightly more light than the flat XR7 tach, but it aint bad (photo exaggerates it).

I am so digging the blue now though.