I have ran into some trouble with my 1989 f150 5L 4x4. The interior lights(speedo, gas gauge, etc) are not working. So first i had an uncle tell me to switch the actual light switch because they sometimes go bad, so i did but that did not solve it. So now i decided to take out everything and get rightinto the bulbs to see if their burnt out. But we need to take the speedo off, and im not quite sure how to do so! If someone has any info, please let me know. Also, im not quite sure how those little bulbs come out!

 

I`m surprised no-one has replied to you before this. If your instrument cluster is the same as my F250 the first thing is to remove the trim surround. This just prises off. From what I remember you will then see the screws holding the instrument cluster. There may be some underneath as well. The cluster should pull streight out. If you have a speedo cable you will have to disconnect it to allow the cluster to be fully removed. You will also have to disconnect the transmission selector indicator cable if auto. However unless you have had a runaway alternator I can`t see that all of the bulbs could have blown. The light switch was a good call but obviously not the problem. Sounds like a fuse or bad connection or bad ground. This should bump the post and maybe someone else will have some ideas.

 

The little bulbs (#194) push into a socket that then twists into the back of the gauge assy. Be VERY careful with the cladding on the flexible circuit board.
One of these bulb holders may have a resistor on it , or it may be on the board. if it's on the holder be sure to put it back in the right place. I say this because I swapped in a new to me cluster from Ebay this December and noticed the difference.



IIRC, you first have to remove both lower sides of the surround. the right first and then the left. On the left you must remove the lights and wiper ***** by pulling on the little metal clip that you can see through a slot on the stem with a pick or hooked scribe tool.
Then you will need a long Torx bit (T-15, I believe). There is one screw that becomes exposed on the left piece when you pry off the right side lower piece.
On the cluster surround there are 2 in the top (above the gauges) and one on either side of the steering column.
And then another 4 holding the instrument bezel itself in.
(hope I remembered them all)

Getting the speedo cable off is a chore. You need to pull out the instruments as far as you can, tilt them to one side and reach in behind, feel your way up the cable to the back of the speedo and you will find a plastic retaining collar that you need to squeeze to release and then pull the cable straight back and off the cluster. It helps if you have small hands and work as much slack cable as you can find up behind the dash.

Hope this helps, and you resolve your lighting problem.

 

Yes that did help. I got everything out now, and it is all sitting there. But i'm not sure quite what to look for? Like what kind of problems could it be? Could it just be the light bulbs? But i know their not all burnt, maybe just one or two. Or could it be the board? Because i switched the light switch(dimmer) so i know its not that. Any more suggestions??

 

I think the whole cluster has a common ground
If you have working idiot lights, I'd check for power @ the plug into the cluster.
If you have no dome (interior) light too I'd check power to the switch.
Dimmer controlled illumination is the brown wire I believe.
If you have variable power there then it must be the flexible circuit board.
The copper foil can corrode at the connector, you can clean that up with a grey scotchbrite.
If you have the cluster out you could try it on the bench, hooking up the ground and jumping power to the various contacts at the plug.

 

Check the plug on the light switch. Ford has a replacement plug available that is much heavier wiring than the original. They have a tendency to burn in the plug and are hard to tell without closely examining them. They can melt and cause problems. Be careful to get the two electrical plugs locked tight on both ends. Had a problem on my 89 because the plug that has the wiring for the alternator light indicator was loose on one end and became an intermitent alternator not charging problem. You may want to clean all the contacts on the cluster where the plugs go in as well as where the lights plug in.

 

You could try a continuity tester. I purchased one cheap that has a needle/probe on one end and a wire with an alligator clip on the other and is powered by 1 AA Battery. I use it on Bulbs and Fuses frequently and when you have continuity a red inside bulb will illuminate. I have found several "new style" fuses to be defective right out of the box eventhough they look fine.

Hold the bulb with some cloth-type material and scrape the silver end on the cement and then touch it with the pin and then touch the brass colored base with the alligator clip and if good the inside light will illuminate. It is a good idea not to touch a bulb with your fingers as the natural oils of our skin conceivably shorten the life of the bulb. At least this is what I was taught.

As far as connector plugs; unplug and replug them a few times and this will clean the connections.

You can Jump a relay but only to determine if this could be an issue as you can cause some "frying of the wiring" if you leave the jumper attached.

Moreover, the reply stating a grounding problem is probably right on target.

Take care.

 

desertdog,
These are 194 style bulbs, just a glass envelope with one of the filiment supports bent to each side of the base.

Mike,
I have heard of the switch plug wiring cooking due to the heat of the coilwound rehostat building resistance over the years as it oxydizes.
If you have no power @ the brown wire going to the instruments I would check this out.