Instrument Cluster Lights (LED) Not Working - New and Old PCB - SOLVED

[foothilltom 33]

Hello all,

I recently decided to re-do my 1969 Gauge Cluster lights (no-tac). I had installed LED lights years ago, and, overtime, I had a few lights that had spotty and intermittent connections and the rattle of the engine combined with LA streets would turn them on and off. Once I pulled the stock PCB (dated Nov 1968!) I saw that the gold/copper "ring" for several of the light sockets were quite worn down and likely the culprit of my one or two flickering lights. ** To clarify, all dash lights work - just one or two goes out occasionally, but a *tap tap* to the cluster will illuminate them again**.

I figured a CJPony parts PCB (printed circuit board) would be a nice upgrade and peace of mind for night driving, but, to my surprise, after the install most of the lights stopped working all together! This prompted a thorough check of all connections with a multimeter, and I could find no break in the circuit on the CJPony PCB or the old PCB. I checked my wiring harness, fuse box, and tested that the wiring harness connector is receiving 12V - all good. 

The only variable that changed is the new PCB, which I promptly took off and re-installed the old one. Then, my well-intentioned, but electrically intermediate brain, decided I will "improve" my light socket connections with a conductive material (aluminum foil) to make up for the worn connections. After taping foil (shiny-side only) around each socket connection and a quick check with the multimeter, I verified all circuits were still operational, and I re-re-installed the old PCB into the car. Unfortunately, my aluminum trick was only partially successful, and I still had some bulbs stay dark and some flicker with movement of the cluster. 

MY QUESTION(s): Any thoughts/ideas as to why the CJPony PCB barely worked at all? Also, has anyone ever "re-invigorated" the light socket connections with success? Perhaps electrical grease or polishing?

For an "incandescent" look, I am using these LED bulbs without any colored diffusers, all of which have been tested and proven to work. 

Pictures of the old, new, and "improved" old PCB. drive-download-20201127T031547Z-001.zip

Edited November 29, 2020 by foothilltom
SOLVED

[danno 128]

There must be insulating pieces between the flextape and the gauges.  If you do not have these, it will short the guages.  I do not know if that could effect the lights.  With it removed from the car, hook up 12 volts to the light connector pin and see if that allows it to work. 

[danno 128]

I am wondering if the ground is good?  Are you checking it with the panel screwed in and connected to chassis ground?  Make sure the ground screw is in on the voltage regulator plate and also in the 

[danno 128]

Did you blow the headlight switch when you were trying the foil idea?   Disconnect teh instruments and see if the light on the heater controls works. 

[aslanefe 333]

Did you try cleaning the contacts on bulb holders and bending the contacts on them a little bit to press more on the board? You can also clean the copper pads on PCB with fine scotch brite to remove oxidation.

[Midlife 814]

LED's are usually polarized, so if the bulb is 180* out, it will not work.  For the bulbs that aren't working on the new card, try rotating the bulbs.  Also, you cannot use LED's for alternator indicator lamps, as the lamp itself is part of the charging circuit. 

[foothilltom 33]

@danno What is this flextape that you speak of? Is that another name for the circuit board? As far as I know there was not any insulating material on the gauges - unless you count some rectangular plastic retaining washers keeping the gauges in place when the nuts are off. As far as the ground goes, I did not check that ground with the cluster hooked up - just on my table with the multimeter. As far as I know, I did not blow anything post foil - all other interior lights are working properly and no fuses are blown. 

@aslanefe I did clean up the points on the sockets and bent them to increase tension (accidentally broke one in the process). I will try cleaning up the copper pads. My only worry is there may not be enough material left to polish and make a good connection.

@Midlife Which one is the alternator indicator lamp? Also, these LED bulbs are for automotive purposes and have a reversible polarity so direction should not matter. I confirmed this with the manufacture.

I appreciate all of the replies so far. I will post any updates/solutions as I get them.

[danno 128]

Yes, I call it a flextape, that is commonly used in teh electronics industry as a circuit board that is flexible. 

The insulator I am referring to is between the circuit board and the gauges. You must have this on each gauge or you will fry things. However, it will not cause the LED's to not work.  I would start by checking for voltage to the circuit board. I think it is the blue/red wire, the second from the end.    Make sure you have 12 volts on this when the lights are on and everything else is off.  

Do The gauges work?  If they do, that tells me you have a ground connection.  If they do not, then that could be the problem.    

To rule out the LED as a potential problem , but you old light bulbs back in and try them.  

[Midlife 814]

When the bulbs are not working, are all of the dash lamp bulbs out?  If so, the problem can be isolated to the dash cluster connector back through the main harness, fuse box and headlight switch.  If only some of the bulbs don't work, the problem is in the dash cluster. 

When I talk about the dash lamps, I only mean those that go in the blue diffuser holes.  Other lamps are for turn signals, and gauge indicator lamps.  Each of those are on separate circuits.

[foothilltom 33]

***SOLVED***

First off, I would like to thank you all for your help. Between all of your insights I was able to figure out the problem.

LONG story short, I hooked a 9V battery to some speaker wire and started poking my fully assembled cluster (now on my kitchen counter) until lights started turning on. To my surprise, sometimes almost all of the lights turned on! WEIRD! After a while I noticed a pattern that when I put voltage across each light socket, one of two things would happen: 1) Only two lights would light up OR 2) All of the other lights besides two would light up. This would happen after changing the polarity of my test by reversing which side on each socket I had the "positive" and "negative" cables from the 9V battery. 

I then checked the forum to post my findings and saw what @danno had said about the insulating brackets so I took apart the cluster again and made sure they were in the correct position. Once I re-assembled the cluster and repeated my earlier test, I got the same results EXCEPT now two different bulbs were lit up (or not lit up depending on the cable polarity).

Once I bashed my head against a wall a few more times, I thought back to what @Midlife said about polarity, and even though the bulbs I purchased have reversible polarity, and, therefore, should not care how they are installed, I thought maybe, just maybe, technology back in 1969 wasn't set up to handle reversible polarity.

I then, in the proper "positive/negative voltage flow" scenario, removed and rotated each bulb, that wasn't lighting up, 180 degrees and BOOM. All bulbs work as intended. What a relief.

TLDR: Even reversible polarity LED bulbs bought from modern manufactures are not reversible in this context. I have no idea why and random chance of how I chose to install each bulb has been my downfall all along. I will definitely be marking my lights and light sockets with a pen from here on out.

Anyways, a test drive to make sure my gauges were working revealed that the only casualty is my fuel gauge, which does not work anymore. @danno this gauge had the insulating brackets in the correct place all along so i'm not too sure why it's suddenly not working, but I am taking the win for tonight.

Pictures attached of my 9V test for those who are curious. I hope this thread helps others who have issues with after market LED's. 

 

[aslanefe 333]

Do the LEDs you use dim when you adjust with the headlight switch?

[foothilltom 33]

They do. Also, dome light, heater light, courtesy light in the ignition, high beam switch, gear shift light - all working properly. 

[Mach1 Driver 560]

FYI in a stock harness only these lights will dim: ash tray, heater, radio, 2 clock, 8 dash lights

https://imgur.com/7IsqEVN

[foothilltom 33]

Last update for this post. After much troubleshooting, the fuel gauge problem was a re-assembly issue with the cluster. Even though the insulation brackets were in the right spot, the posts on the back of the gauge were contacting the cluster housing, grounding them out. I put some electrical tape around the inside of the housing where the posts slide through and it worked. Seems like a bad design, in my opinion, but it worked for 15 years before I messed with it so what are you going to do?

Got the idea from this video I found in an old forum. Hope it helps somebody else. 

[69RavenConv 286]

Nice work, Tom. That's a common problem, often difficult to diagnose. You're right, it's not a great design.

[Midlife 814]

Yup, it is a terrible design.  Ford went to plastic housings in 1971.  This problem was one of the reasons I make hard-wired dash cluster harnesses to get rid of the circuit card, which was often blamed for gauge problems.  To replace the circuit card, you must undo the nuts holding the gauge in place, which allows the gauge to move and have the posts contact the metal housing.  But only without the circuit card, you can test continuity between the posts and the chassis: should be very high.  If you see 14 or 0 ohms, then you know one of the posts is touching.  With the circuit card in place, a touched post causes all the non-ammeter gauges to read 14 or 0 ohms to metal chassis, and you can't tell which one is causing the problem.