Low voltage idiot light on after Instrument Cluster R&R / MerkMeter Install

[DPDISXR4Ti]

The other thing you might check is that none of the traces on the flexible printed circuit have moved out of the way where the red and green connectors are. They have a tendency to delaminate and then they can fold over.

Yes, I've noticed that. The section that always seems to delaminate is where it hangs down below the housing behind the tach. With the cluster that's in there now I glued it back together with some gel Gorilla super glue, which is NOT conductive.

At least I'm not blowing fuses now. I blew a total of 3 - always with the original cluster. Perhaps it wasn't ever related to the MerkMeter install, but it certainly felt like it.

[Ed Lijewski]

Dean: is there a safe liquid cleaner to use on the copper contact surfaces?

20210105_102928_copy_756x756.jpg (119.42 KiB) Viewed 2621 times

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[brokencase]

Maybe something like Tarn-X. But I doubt that is an issue here.

[Ed Lijewski]

Didn't imply it was. That's a pic of one of my good spares, which I noticed is tarnished except in the exact bulb contact spots. For the next cluster R&R I thought it would be worth addressing to assure the bulbs get full voltage.

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[brokencase]

Weird coincidence, but I was flipping through the channels and stumbled momentarily on "Moonshiners". There was a guy on there cleaning off the green oxide on a copper still and I think he said he was using a mixture of hydrogen peroxide and citric acid. Looked like it was doing the job.

[Ed Lijewski]

Dean: There is a market for Merkmeters which you no doubt could easily supply (I'm not a buyer but it appears others are).
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I'll have to think about that Ed. I just checked ebay and I see this...
https://www.ebay.com/itm/3-7V-LM3914-Ba ... 3333733281
That can easily do it in a cinch. You probably only have to adjust the potentiometers to set the range and it probably needs a 5v regulator to run in the automotive environment.

However I think the task is better achieved with one of the new Arduino compatible microcontrollers, like this one I have been playing around with..
ttgo.jpg

That little board is $10. It has a color display and has bluetooth and wifi capability. Dual core 240mhz with 4mb ram. It is actually way overkill for a lambda meter, but you could do some other cool things like have it record like a data logger and then display long term data on your cellphone or tablet.

$10...how dos they do it?

So, I see these boards

https://www.ebay.com/i/113333733281?ul_ ... noapp=true

can easily serve as a stepped voltage monitor (see info on website). Not a precise indicator but one quite useful to indicate if there is problem looming or on your doorstep. Every care should have a way to monitor voltage trend. As this board would fit in that lower center niche in the cluster it would a great addition to the Scorpio cluster. And it would be preferable to the cigarette lighter plug-in voltage reader which will drain a battery if left plugged in over time should the car not be used regularly.

If you set up say 15-20 of these on your work bench you'll be able sell them rapidly.

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[DPDISXR4Ti]

I'll also try adding that additional ground circuit between the body and lug C.

Now that we've got the forum back up and running I can provide a (minor) update. I went ahead and added the Gnd circuit between the body and lug C. For a brief moment I now get a flicker of one LED from the MerkMeter when I turn the ignition on. But that's all. Nothing at all from it while running, cold or once the engine is fully warmed up.

The only other thing is that the coolant gauge is properly working now, but not the fuel gauge. Additionally, the low-fuel idiot light is always on. Tank is nearly full BTW.

Next steps are making sure I've actually got a signal from the O2 sensor and figuring out if I've actually got a fuel gauge issue or a signal issue feeding the gauge.

[DPDISXR4Ti]

So, the nightmare continues.... I decided to put the MerkMeter to the side and focus on getting a fully functional cluster. Mixing and matching parts from the four clusters, I finally got one with a functional tach, charging the alternator, and functional coolant temp / fuel gauge. You might think I buttoned things back up at that point and forgot about an A/F meter, but I'm stubborn, to a fault apparently.

I then installed the MerkMeter in this perfectly functioning cluster. I actually had another MerkMeter, so I even went ahead and put that one in, just in case there was something weird going on with the other one. With directions now in hand, I properly hooked up the 12V+ and - terminals. Re-installed the cluster, turned to the Acc position, no Alternator or low oil pressure light and no fuel gauge. Started the engine up any way, no tach and voltage drops to 11.8x or so - I'm not charging. Rev'd the engine to 3000 RPM with no change.

Whiskey, Tango, Foxtrot!!!!

Since them, I've tried a couple of the other clusters and I do get the alternator and oil pressure lights coming on, so I assume the charge function will work with those. I also tried removing the anti-slosh module on the previously functional cluster with no change.

I can't imagine how the MerkMeter could be killing something in the clusters, but it appears to me that's what has happened. Bizarre...

[Ed Lijewski]

Is the green female center connector in one piece or in two parts (broken during removal, a common fact)? A two section connector still works but occasionally on remounting in the IP one part loosens contacts on the printed circuit tracks.

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[DPDISXR4Ti]

Is the green female center connector in one piece or in two parts (broken during removal, a common fact)? A two section connector still works but occasionally on remounting in the IP one part loosens contacts on the printed circuit tracks.

Both the green and red connectors are broken in two. Darren addressed this really well with a velcro strap that you put over the connector to positively fasten it in place. I've gotten pretty good at making sure it's seated in place. I'm confident that's not the issue.

[Ed Lijewski]

Could you show pics of how the Velcro strap is installed?

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[DPDISXR4Ti]

Could you show pics of how the Velcro strap is installed?

Look back on page 2 about 1/3rd of the way down - you'll find a pic.

Replaced the fuel/temp gauge assembly last night. Reinstalled cluster and all my idiot lights are now illuminating as they should when key moved to the On position, most notably the alternator and oil pressure lights. I'll take the car for test-drive later today to make sure the battery is charging and see how the other functions are doing.

What a long, strange trip it's been....

[Ed Lijewski]

So both red and green harness connector ends are intact? That was what I wasn't clear on.

The red and green connectors are removable without damaging them. Why not install a good red one from your other clusters?

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[DPDISXR4Ti]

So both red and green harness connector ends are intact? That was what I wasn't clear on.

The red and green connectors are removable without damaging them. Why not install a good red one from your other clusters?

The receiving connectors on the cluster are totally fine. I've had them on and off several times as I've swapped parts from various clusters in my collection.

It's the connectors on the harness side which are broken (roughly) in half. I've considered harvesting the ones from my parts car along with some wire attached and getting some more harness length to work with in the process, but that's a lot of splices to make and I'd rather not go down that path right now.

[DPDISXR4Ti]

Replaced the fuel/temp gauge assembly last night. Reinstalled cluster and all my idiot lights are now illuminating as they should when key moved to the On position, most notably the alternator and oil pressure lights. I'll take the car for test-drive later today to make sure the battery is charging and see how the other functions are doing.

Clearly I jinxed myself with my over-confidence of last night's re-installed cluster.

I hadn't yet installed the clear plastic face-plate so the cluster needed to come back out. Upon re-installation, the alternator and oil pressure lights are NOT coming on. I tried the two other clusters which also successfully had those lights turning on last night, and with those too, no alternator and oil pressure lights. Of note, the brake pad light (also on the left side) does flash for ~10 seconds on power-up for all three clusters, as do a couple of the idiot lights on the right side. So I am getting power to the cluster, but maybe not to everywhere it needs to get to?

Based on this experience, I can only assume that there is some sort of connection issue on the harness side. Based on what I have experienced previously I assume that the alternator will not charge the battery unless I'm getting power through the alternator light in the cluster.