84 F-250 - no dash lights or gauges

[Coco]

hey all, i’m stumped and i really gotta get this problem fixed asap.

i had my headlight switch replaced by a mechanic a while ago, due to no headlights or dash lights. before, i had some dash lights like turn signals, seatbelt, and all gauges worked besides oil.

now, i have headlights, and all exterior lights, but nothings on the dash? high beam light works now, and the seatbelt light but that’s it. i have gauge lights, albeit dim and nearly useless at night, but now no gauges work. i’ve checked the fuses and they’re all fine. i’ve replaced everything that was blown, and still nothing. i really don’t know what the problem could be, although i’ve heard from coworkers/experienced people that i might have to tear the dash apart to fix the lights, but that doesn’t explain the sudden loss of gauges.

i need to have at the very least a fuel tank gauge for either front or rear tank, since i have a date this sunday with someone, and im picking her up in the truck.

if anyone knows any possible fixes please let me know!! im at a complete loss rn, other than taking the truck into a different shop and seeing if they can undo whatever the previous shop did

[Coco]

some more information that might be helpful for anyone:

ac control panel does have light. radio and horn both work, and the dimmer functions normally for the instrument panel light when twisted. i don’t have a dome light; im assuming the bulb burned out a long time ago, because the dome light cover is missing. i’m going to replace the bulb and see if it works when put in, but i’m really not sure what the problem could be. it isn’t fuses, and i have no idea how it could be wiring since it all worked before?

[BigBrother-84]

some more information that might be helpful for anyone:

ac control panel does have light. radio and horn both work, and the dimmer functions normally for the instrument panel light when twisted. i don’t have a dome light; im assuming the bulb burned out a long time ago, because the dome light cover is missing. i’m going to replace the bulb and see if it works when put in, but i’m really not sure what the problem could be. it isn’t fuses, and i have no idea how it could be wiring since it all worked before?

Hi,

About the dome light question, you can find detailed information here.

For the other lights/cluster gauges, not sure about what is now working or not.

Do the gauges themselves work, or just the lighting is gone?

[Gary Lewis]

I'll proceed with the assumption that the answer to Jeff's question is that the gauge lights work, albeit very dimly, but the gauges themselves don't.

On the gauge lights being very dim, that is par for the course. The incandescent bulbs are weak, the inside of the gauge housing has grown brown from the heat so reflects little light, and the blue plastic filters have grown opaque. The solution to that is to pull the gauge cluster and replace the bulbs with the right LEDs and remove the filters. And I recommend the HIPO LEDs as they work great and don't care which way you put them in.

But don't do that before figuring out what the gauge problem is as you may need to be in there for that. And there is one major thing that can stop the gauges from working - the instrument cluster voltage regulator, or ICVR. Unfortunately it is on the back of the gauge cluster so if it is bad the cluster has to come out.

So let's test to see if that might be the problem. Take the R/W wire off the coolant temp sensor, or the W/R wire off the oil pressure sensor, and ground it. Then turn the key to On and the appropriate gauge should climb to full scale. If that happens the ICVR is working.

If that doesn't happen then the ICVR apparently isn't working. But it cannot work if it doesn't have power. You can see from the schematic that power comes from Y on Page 22, and if you go there you'll find that Fuse Link W provides the power, and it is the blue wire on the battery side of the starter relay/solenoid. However, it also provides power to the radio, digital clock, windshield washer, & speed control. So if those things work then Fuse Link W is good.

So if the gauges don't work and the other things do then it must be the ICVR that's bad. But do those tests before we get into how to fix an ICVR.

[Coco]

I'll proceed with the assumption that the answer to Jeff's question is that the gauge lights work, albeit very dimly, but the gauges themselves don't.

On the gauge lights being very dim, that is par for the course. The incandescent bulbs are weak, the inside of the gauge housing has grown brown from the heat so reflects little light, and the blue plastic filters have grown opaque. The solution to that is to pull the gauge cluster and replace the bulbs with the right LEDs and remove the filters. And I recommend the HIPO LEDs as they work great and don't care which way you put them in.

But don't do that before figuring out what the gauge problem is as you may need to be in there for that. And there is one major thing that can stop the gauges from working - the instrument cluster voltage regulator, or ICVR. Unfortunately it is on the back of the gauge cluster so if it is bad the cluster has to come out.

So let's test to see if that might be the problem. Take the R/W wire off the coolant temp sensor, or the W/R wire off the oil pressure sensor, and ground it. Then turn the key to On and the appropriate gauge should climb to full scale. If that happens the ICVR is working.

If that doesn't happen then the ICVR apparently isn't working. But it cannot work if it doesn't have power. You can see from the schematic that power comes from Y on Page 22, and if you go there you'll find that Fuse Link W provides the power, and it is the blue wire on the battery side of the starter relay/solenoid. However, it also provides power to the radio, digital clock, windshield washer, & speed control. So if those things work then Fuse Link W is good.

So if the gauges don't work and the other things do then it must be the ICVR that's bad. But do those tests before we get into how to fix an ICVR.

sorry for the confusion!! yes, the gauge lights work, but there are no gauges. i can confirm that windshield wipers, and radio work for sure. i don’t have a digital clock, and i haven’t had a chance to try speed control yet.

i’ll plan on pulling the dash apart next week—i think for sunday i’ll just fill up the front tank again with diesel and then fill the rear to at least half, and top off on all fluids just in case. how am i going to know if the ICVR is bad, or is the only way to unplug it and ground a gauge?

[Gary Lewis]

sorry for the confusion!! yes, the gauge lights work, but there are no gauges. i can confirm that windshield wipers, and radio work for sure. i don’t have a digital clock, and i haven’t had a chance to try speed control yet.

i’ll plan on pulling the dash apart next week—i think for sunday i’ll just fill up the front tank again with diesel and then fill the rear to at least half, and top off on all fluids just in case. how am i going to know if the ICVR is bad, or is the only way to unplug it and ground a gauge?

I think your plan is a good one.

As for the ICVR, if two gauges don’t work it pretty well has to be the problem. So test the oil pressure and coolant temp and if both fail that has to be it since the fuse link must be good.

But you will want to have LEDs and a new/better ICVR on hand when you take the gauges out. I’m at our church building now so can’t get the links easily, but I recommend the HIPO LEDs and a solid state ICVR.

[Coco]

I think your plan is a good one.

As for the ICVR, if two gauges don’t work it pretty well has to be the problem. So test the oil pressure and coolant temp and if both fail that has to be it since the fuse link must be good.

But you will want to have LEDs and a new/better ICVR on hand when you take the gauges out. I’m at our church building now so can’t get the links easily, but I recommend the HIPO LEDs and a solid state ICVR.

okay, awesome thank you!! i’ll find part numbers for the dash lights today at work to cross reference on amazon for LED counterparts. one of my coworkers is super super adamant about LED swapping all lights because they’re better for the vehicle and the driver, so i’ll probably replace all the bulbs when i do the ICVR.

i did see a video today where a guy was explaining how he fixed his fuel gauge, and he pulled the tank selector switch and cleaned it so the connection was good enough to carry the relay. jim, (the owner of the truck just before me) said that he’d sometimes run into an issue where the fuel tank wouldn’t switch properly, and he’d have to flip it back and then switch to the desired tank again to get the tanks to switch. should i start with replacing that switch as well, if it still has troubles with the gauges after the ICVR?

[Gary Lewis]

okay, awesome thank you!! i’ll find part numbers for the dash lights today at work to cross reference on amazon for LED counterparts. one of my coworkers is super super adamant about LED swapping all lights because they’re better for the vehicle and the driver, so i’ll probably replace all the bulbs when i do the ICVR.

i did see a video today where a guy was explaining how he fixed his fuel gauge, and he pulled the tank selector switch and cleaned it so the connection was good enough to carry the relay. jim, (the owner of the truck just before me) said that he’d sometimes run into an issue where the fuel tank wouldn’t switch properly, and he’d have to flip it back and then switch to the desired tank again to get the tanks to switch. should i start with replacing that switch as well, if it still has troubles with the gauges after the ICVR?

Home for lunch, so will try to answer some of the implied questions.

First, be really careful when replacing incandescent bulbs with LEDs. One reason is that the bulbs our trucks use are industry standards and the reflectors have been engineered to work with them. And to my knowledge no LED meets the standards.

The standards include the exact placement & orientation of the filament when the bulb is properly seated. But LEDs do not have a filament, and their diodes aren't in the same place nor oriented the same as the filament. So the light comes out at different angles and directions and that won't work properly with the existing reflectors & lenses.

As a test, I put a brand new 1157 in the brand new left taillight on Big Blue and an 1157 LED replacement in the brand new right taillight. At night I turned the lights on and took a picture which showed the incandescent noticeably brighter than the LED. Then I tried the stop lights and got the same results. But I shouldn't have been surprised as the taillights were engineered for an 1157 and its filament placement, not the LED.

I've done quite a bit of research about this, but absolutely nothing in comparison to what Daniel Stern, a lighting consultant, has done. You can see some of my results in a thread called Lighting Upgrades. But you should read what I've posted that Daniel has sent me as it is scientifically proven.

For instrument lighting there's another thread, and this post in Instrument Lighting & Paint Testing is probably the key. However, you might want to start on the first post of that thread as there are links to the HIPO LEDs as well as tests of them against some others. And don't miss Jeff's recent post in that thread.

One thing to be aware of is that the HIPO LEDs are not polarized, meaning you can put them in either way 'round and they'll work. But that is not true of most other LEDs, so when you get your dash together only about half of them will work and you'll have to take the cluster out and turn those around.

Plus the HIPO LEDs project to the sides and not to the ends. And in the instrument cluster that's important as most of the light emitted off the end is wasted.

I'm not saying I have all the answers. But I have done some testing and have gotten some good and bad results. So I wanted to share those so you don't have to get the same bad results.

[81-F150-Explorer]

okay, awesome thank you!! i’ll find part numbers for the dash lights today at work to cross reference on amazon for LED counterparts. one of my coworkers is super super adamant about LED swapping all lights because they’re better for the vehicle and the driver, so i’ll probably replace all the bulbs when i do the ICVR.

i did see a video today where a guy was explaining how he fixed his fuel gauge, and he pulled the tank selector switch and cleaned it so the connection was good enough to carry the relay. jim, (the owner of the truck just before me) said that he’d sometimes run into an issue where the fuel tank wouldn’t switch properly, and he’d have to flip it back and then switch to the desired tank again to get the tanks to switch. should i start with replacing that switch as well, if it still has troubles with the gauges after the ICVR?

If the plastic of the instrument cluster is really brown. I'd recommend replacing or painting it back to white.

The white plastic is used as a reflective surface for the instrument cluster illumination.

 

[Coco]

Home for lunch, so will try to answer some of the implied questions.

First, be really careful when replacing incandescent bulbs with LEDs. One reason is that the bulbs our trucks use are industry standards and the reflectors have been engineered to work with them. And to my knowledge no LED meets the standards.

The standards include the exact placement & orientation of the filament when the bulb is properly seated. But LEDs do not have a filament, and their diodes aren't in the same place nor oriented the same as the filament. So the light comes out at different angles and directions and that won't work properly with the existing reflectors & lenses.

As a test, I put a brand new 1157 in the brand new left taillight on Big Blue and an 1157 LED replacement in the brand new right taillight. At night I turned the lights on and took a picture which showed the incandescent noticeably brighter than the LED. Then I tried the stop lights and got the same results. But I shouldn't have been surprised as the taillights were engineered for an 1157 and its filament placement, not the LED.

I've done quite a bit of research about this, but absolutely nothing in comparison to what Daniel Stern, a lighting consultant, has done. You can see some of my results in a thread called Lighting Upgrades. But you should read what I've posted that Daniel has sent me as it is scientifically proven.

For instrument lighting there's another thread, and this post in Instrument Lighting & Paint Testing is probably the key. However, you might want to start on the first post of that thread as there are links to the HIPO LEDs as well as tests of them against some others. And don't miss Jeff's recent post in that thread.

One thing to be aware of is that the HIPO LEDs are not polarized, meaning you can put them in either way 'round and they'll work. But that is not true of most other LEDs, so when you get your dash together only about half of them will work and you'll have to take the cluster out and turn those around.

Plus the HIPO LEDs project to the sides and not to the ends. And in the instrument cluster that's important as most of the light emitted off the end is wasted.

I'm not saying I have all the answers. But I have done some testing and have gotten some good and bad results. So I wanted to share those so you don't have to get the same bad results.

ooh wow there’s a lot more to the LEDs than i thought. i might stick with stock lights and replace the bulbs with OEM ones instead. the lights that DO/did work are bright enough i haven’t had any issues seeing them. it’s only the panel lights that are dim; although i know that’s on every old Ford rig out there. My old ‘90 F-250 was the same way, and so is my ‘90 Ranger.

i’m trying to look up the ICVR thing for the gauges though, since i’m at work at oreillys right now, but can’t pull anything up. is there a part number or something specific that it could be called anyone knows of that might help my computer pull it up?