I had 2 dash bulbs out. So I went and replaced all of them with led's. Now, the two that were out are fine and a different location is out. I switched the connectors around to see if I had a bad one and that is not the problem. I am at a loss...
What could be causing this?

Thank you for any and all guidance. Trying to keep my head above the water...

 

I also wanted to mention that when I twisted them out, it almost seemed like they had become stuck, somehow, to the sheet(?) that it touches after it is twisted back in. I assume that sheet is where the connections is make it light up

 

You're correct, the plastic flex circuit is where the contact is made. Do you happen to have a multimeter with a diode test function? Or better yet, do you have a small power supply that will allow you to power the instrument illumination circuit by itself? Did you get LED bulbs that snap in in place of the 194 bulbs, or did you get complete assemblies that include the little twist base as well?

-Rod

 

Hi
They were just individual bulbs that I placed into the holders.
I did try a new led bulb into the holder in case it was a bad bulb.
Also, I moved bulbs around to make sure it was not the bulb or holder.
That is why I suspect it is with the plastic flex circuit or maybe I should use regular bulbs.
**** found the meter setting to test the diodes. What am I looking for?

The bulb that I am pointing to is the one that will not work.

 

I don't have a power supply to use. What would qualify as a power supply? Is it something I can go get? What does the diode test function look like? I have a multimeter.

Is it possible it does not work properly with led's? Just grasping!!

 

It should work with LEDs, but if you bought standard LEDs that don't include a bridge rectifier, they will be polarity specific. The symbol for diode test will look something like --|>-- and this can be used to determine 1) if the LEDs you have are polarity sensitive, 2) if the diode is still good, and 3) which way to install the LEDs.

I'm struggling to get my factory service manual to work currently, but there should be a common ground for all of the instrument illumination bulbs. It may be marked on the flex circuits with a "-" or the other copper pad may be marked with a "+" or say something like "ILL+". Using the diode test function of the multimeter, connect the red meter probe to one of the bulb twist lock bulb holder contact buttons and connect the black meter probe to the other bulb holder contact button with the LED bulb in the twist lock connector. If the LED is NOT polarity sensitive or you have the meter connected to properly bias the LED you should see some voltage reading on the meter. Depending on the meter, the LED may also be glowing faintly. If your meter displays OL, the same as what it shows if the probes are not connected to anything, then reverse which twist lock buttons your probes are on (switch the red with the black and vice versa). If you still read OL, either the LED bulb is bad, the bulb is not making a good connection with the twist lock bulb holder, or the twist lock bulb holder is bad.

If you get a voltage reading with both wiring tests, then the LED is not polarity sensitive and it should not matter which way you install the bulb holder. If you get a reading with only one of the tests, then the LED IS polarity sensitive you and you need to make sure button contact that has the black meter lead connected to it when the meter reads a voltage is connected to the common ground of the instrument illumination. If the polarity is marked on the flex circuit that will make things easy. If not, then you will need to take some continuity tests. You could very carefully remove one of the working LEDs, being very careful to keep track of which direction it was installed. Use the diode test to determine the polarity of that LED, then use the continuity test (or diode test) to determine which of the two copper contact points the black meter probe side of the bulb holder is connected to between both bulb installation points. I'm not sure I'm wording that the best, so hopefully it makes sense.

If you end up with a power supply (which for this could just be a 9V battery) you could apply power to the contact points for the illumination circuit after determining positive and negative, then connect the suspect LED in each direction to determine which orientation is the correct way.

-Rod

 

I figured out my issue with the service manual. The attached diagram should help with determining which connection point is ground and which is power. The terminals highlighted in yellow are what you should be interested in.

-Rod


Instrument Illumination for the 1996 Explorer.

 

Ok. But I moved that bulb with the holder to another spot and it worked fine. And moved a working one to the hole on the board and it did not work.
Will your instructions help determine if it is on the board or one of the diodes on the board itself?

 

Yes. If you test the LED and determine that either it is polarity sensitive, then you'll need to try reversing the direction (which you may have been lucky and done when you relocated it). If you test for continuity between the connector C286 pin 7 to the bulb socket contact point and C286 pin 8 to the adjacent bulb contact point, or C287 pin 4 to the bulb socket contact point and C287 pin 7 to the adjacent bulb contact point you'll know if the issue is with the board.

For reference, C286 is the white 16 contact connector and C287 is the black 12 contact connector. In the image you posted above, that would appear to show the connection for C286 and the connection numbers appear to be listed on the board. From what I can see if I zoom in on your photo, it appears the contact for the bulb connects with pin 8 of C286, therefore if your LED is polarity sensitive, that should be the anode side of the LED, which would be the side that the red multimeter probe is connected to when you get a voltage drop reading during the meter diode test.

-Rod

 

Thank so much for your time and help...It is invaluable!!!

It is now working....

So, I embarked on this by myself. My husband decided to get involved and with that, we both missed changing out one of the old bulbs to the l.e.d. (one way at the top of the cluster), which was not noticeable until I had the cluster out completely. Changing that bulb, then made it all work. Only issue, I have a screw left over! But I will take it!

 

I'm glad to hear you got the illumination working. Since all three bulbs on that leg of the circuit are in parallel, having one that was not an LED, even if it was burned out, would not explain another one not working. I'd be more inclined to think either one wasn't making a good connection and got wiggled, or the LEDs are polarity sensitive and the bulb got removed and reinstalled with the correct polarity. But at this point I guess there's no reason to mess with success.

-Rod

 

I have a 96. I converted to Led 10 years ago. They never worked right, there was always one or two that didn't light reliably (sometimes they would be off). I could pull the cluster, wiggle, and it would work for a while. Got tired of that.
The LEDs only have a single wire, the regular bulbs have two. They just don't make good contact in some connectors. Never had an issue with regular bulbs.
When I take it apart again, I am going to install a small piece of aluminum foil in the connector. Some of the LEDs work perfectly though.

If your old bulbs were working properly, I doubt very much there is a cluster issue. If you put the old bulbs back and everything is fine - you probably have the same issue as me.