I pulled the instrument cluster out and from what I can see, I don't see any breaks or tears, etc. from where the CEL bulb plugs into where the connector plugs in. I am going to stop for now. I took some more pictures (below). There is an aftermarket switch down by where the hood release is. Any ideas what this is? Could it somehow be related to the CEL problem? I am wondering if it could be a towing light kit of some type? I read on another post somewhere about how those can cause problems. Also, I was thinking, that steady blinking on my test light when I am plugged into W with the test light with the jumper between TE1 and E1.... it makes sense that there would be no code. I unplugged the negative battery cable earlier while ripping the dash apart. I have it unplugged again now that I have the dash ripped apart again.

Connector and wires that connect to the after market switch

A couple of fuses in the same general area.

Some sort of plug behind where I am holding the fuses

After market switch

This is by the back bumper. Is this to plug trailer lights into?

 

Constantly blinking. As in a steady, even, flashing test light? If there are any breaks in a steady pattern, it's showing a code. Like if it flashes 2 times, a short pause, and 4 flashes, and then repeats, that's a code 24, you see? If it just flashes a steady pulse, no variations, THAT means no code. The trick is to be certain there's never any variation to the pattern over about a minute.
If it does indicate a code, make sure you cleared any old codes out. Either pull the EFI fuse for about a minute, or, as I prefer, pull the battery negative lead off for a minute or more. This makes sure to clear any codes that have been stored in what little memory the ECU has, so you don't end up chasing a problem that's been fixed already.
Make sure to jumper T1-E1 to try and read codes. Turn the key all the way off, put the jumper in, then, with your test light in place, turn the key on. If there are any code they will show as I said above. So many flashes, short pause, then another set of flashes, then a slightly longer pause, then the first number of flashes, pause, second number, pause, etc etc. I use a short piece of wire, with make spade terminals that fit the DLC1 female terminals as a jumper, but many people use a more expensive solution. They use a paperclip bent to fit. Probably a good quarter cent or so. Very expensive

Not necessarily are you doing something wrong. It may be there's no voltage on the Gauges fuse. This tells you something important. It tells you you need to trace the power source for the Gauge fuse back to it's origin. It also means you need to now learn to read a schematic, you lucky dog! A schematic is like a road map, that shows where electricity goes. I won't get into electron vs. hole flow, here. BTW, I'm lousy at drawing thing on pictures, to show visually what's going on. I'm as artistic as a sick tortoise, ok? Bear with me.


Refer to the picture above as I talk, ok? That is a small part of the schematic for your truck.
OK, to trace down what's happening, first, find the Gauges fuse on the picture. Lower right corner. The "S" shape indicates a fuse. You can see a line come out of that grey block with the Gauges fuse in it, marked B-Y. That means the color of the wire is Black, with a Yellow stripe. Notice the line is also colored to help you follow across multiple pages. Most schematics from my day didn't have that feature, but then, most systems I worked on, all the wires were white. We always knew it was the white wire Follow it to the little box it goes to, marked Ignition Switch. That's the key. Note it can connect the far side, little triangle, to ACC, IG1, and ST1. Acc is Accessory, the first switch position. The second is IG1, that's when the key is in RUN, or ON position. ST1 is STArt. Why the 1's? Because the switch has 2 halves. The 1 indicate the first half of the switch.
Imagine the key is ON. The switch would connect to IG1, so keep following the line you were on. Notice it became a White wire, marked W, drawn in white, oddly enough. Follow the white line up the picture. Now it gets a little confusing. The box it goes to is the engine compartment fuse box. It goes through a funny "S" shaped device. Those are fusible links. USUALLY that's a wire of a very specific size. It will burn through at a very specific current load, and normally has an extra thick, soft insulation. This allows the wire to burn, without coming out and burning setting something on fire. In this case it could be with one of what LOOK like fuse, just real big. Marked AM1, AM2, etc. Toyota calls them fusible links , but most of them are really just high current fuses. The ones that are cubical, with a clear top. Some are actually real fusible links, like the wire from the battery to the engine fuse box, or the wire from the high power lead of the alternator.
OK, so now your tracing through a fusuble link. You need to use the screws that attach the wires to it on the back of it. The section of the fuse box with the fusible links in it slides up and out of the fuse box. There's a catch on the side facing the quarter panel. Slide the fusible links up and out, and check them just like you would a fuse. Ohms 20, or ohms2, a lead on each side.

NOTE: PULL BOTH battery leads off before you use your meter to measure ohms. If you don't, the voltage from the battery can, and will, damage the meter. Normally, meters have a small fuse in them to prevent damaging the meter, but why take a chance?

Ok, if AM1, red arrow, reads good, follow your line some more. See it goes to the 100, or 80 Amp fusible link. That's the heavy, white wire from the alternator to the engine fuse block. Check the 100, or 80, whichever it is, fusible link, although you'd have a lot, a LOT, more wrong if it were bad. Chances are, it's the AM1 fusible link, although that should cause other troubles. Once you have FOUND all these items, you can also check the wires between them. Ohms 20, one lead at one end of the wire you want to check, one at the other. You can make an extender out of a piece of regular ol' wire if your leads don't reach. This is often the case in vehicles.

OK, I have to go eat. Today's lesson is now over
Good luck!
Pat☺
Anyway

 

Maybe I missed it where you already did but, have you checked the CEL bulb? You can just swap it with one that you know works like the battery or blinker bulb. Might as well do that since the cluster is now out

 

Yes, the lack of voltage to ground on either pin of the gauge fuse is an important clue. But before you start trying to trace wires, think. Do your wipers or turn signals work (key-on)? If they do, you know that there is power on the B-Y wire. You don't need to trace the wire back to the ignition switch, or worry about the ignition switch.

So then, check for voltage to ground on the wiper fuse. You know that fuse works and has power, so this checks your measurement technique. Then pull the gauge fuse out, and check for voltage to ground on each connector. It is possible that one of the fuse connectors is so messed up that it no longer makes a good connection to the fuse. Or that it is disconnected inside the fuse block.

Or, if both the wipers and turn signals are out, that's a sign you don't have power to the fuse block on the B-Y. (Again, check your technique by looking for voltage to ground on the fuse pins.) You could have a bad wire, but the most likely culprit is the ignition switch. Back AT the ignition switch, back-probe pin1 (where B-Y) connects to look for voltage with key-on.

Electrical is all about divide and conquer. Figure out where you have power and where you don't, then move in the appropriate direction. Don't start tracing wires that you should know already are working.

And yes, a steady 2-hz blinking on the W line means "no codes." That's good news!

The connector at back is a fairly standard trailer wiring connector. But there is no guaranty it was installed well. Any guess what the switch is for?

 

Yep, I swapped it with the one that shows the back window is open. I know that one works because it was always on (when the rear window actuator was replaced, they forgot to put a piece back it would think the window was open all the time, light always on). Oddly though... that back window light was always on, and now it is no longer on after swapping it with the bulb for CEL. And the CEL isn't on, either. So I may try swapping with some other bulbs while I have it out and see what lights and what doesn't.

 

Wipers and turn signals work, yes. So far as I know the CEL is the ONLY thing that doesn't work. When I am testing all of this, do I have the multimeter set to DC 20? And then if I put the black connector on the frame of the car, does that ground it? I am so dumb with this, I am not sure I am even using the multimeter to correctly to test this stuff.

That is good news about the blinking light! It makes sense to me that there would be no codes as I had the negative cable of the battery disconnected while messing with the dash and haven't really driven it enough since it was connected again to get any codes.

No idea what that switch is for.

 

@2ToyGuy yep I used a paper clip as a jumper, it seems to work well! I watched the test light blink for a while, it never pauses just constant blink blink blink blink. Given that the negative battery cable has been unhooked, it makes sense to me that right now there probably are no codes. So is this telling me that the ECU and the diagnostic block are talking together?

The fact that other lights are coming on the instrument cluster, such as cruise, 4wd, brakes, battery, etc. doesn't that mean the Gauges fuse is okay? Also, I have a Chilton manual and it talks about fuse number 4 IGN is "discharge warning light, emission control system, electronically controlled automatic transmission" (which it has a manual so wouldn't be applicable). Maybe I need to be looking at that one?

The rest... thank you for everything you wrote. I will look more at it tomorrow!

 

Use your test procedure, whatever it is, on something "known good." If the wipers work, the wiper fuse has to have power, so test there. You're looking for battery voltage (in your case around 12.5v) to ground. So the 20 range in DCV is just what you want. (Incidentally, here is where a test light is probably better than multimeter; you're not trying to look at numbers while holding probes.)

The frame is always at ground, but sometimes it's not obvious how to get there. Painted metal usually won't conduct; look for a fastener into the metal. Sheet metal isn't always grounded (e.g., the box of a pickup is mounted on rubber vibration isolators, so the taillights have a wired ground, not to the box.)

 

UPDATE! EXCITEMENT! THE CHECK ENGINE LIGHT COMES ON! Never have I been so excited to see a check engine light! The bottom line: it must have been the bulb all along. While I had the instrument cluster out, I swapped some more bulbs around and now CEL does come on! I will likely end up buying a fresh set of bulbs and replace them all but for now... I can move forward! Thank you to all who helped me, I have learned a lot!!

 

I thought, which is always a bad idea, I know, that you said early on that you had replaced the bulb already. Am I mistaken?
It's never been a problem I've heard of with these small little bulbs, but some real high power bulbs, you can NOT touch. The body oils off your fingers will get hotter than the rest of the glass, and shatter it. We're talking street light type bulbs. Having said that, could that have happened in your case, with the small bulb you put in? Could you have squeezed a little, and cracked the glass? Could the bulb you put in not have been rated for the same voltage as the original? Could the contacts not have matched up? Are you certain the bulb you installed was good?
Generally, not always, but generally, when these bulbs go bad the get some black soot inside them, so they're pretty easy to see. Often, you can also see the filament if it has burnt open. If you're anything like me, approaching lower middle age <ahem>, a magnifying glass is of huge benefit for that.
You can also check it with your meter. Take it out of the circuit. Ohms 20, one lead on each contact. Should read something, but a very small value.

I'm just trying to figure out how you might have already replaced the bulb, but still had it not work. I am very glad it's working now, though, whatever the reason. Now, you might want to check for any codes that may be stored in the ECU.
When you order all new bulbs, make sure you get the right part number in the right position. I don't KNOW there are different bulbs in different positions, but it doesn't hurt to be sure.

Yes. Probably the shortest answer I've ever given.

Not necessarily. Different sets of lights are supplied from different fuses. Like 4WD light might be on the Gauge fuse, but the seat belt warning is on something totally separate. Maybe the IGN fuse. JUST AS AN EXAMPLE. You need to consult the schematic to see what lights get their power from what fuse.

Difference is huge between ignorant, and stupid. You merely lack experience. That's a huge difference from someone that can't figure out which end of the meter is UP.
Yes, the frame is usually grounded. Having said that, don't confuse "frame" and "body". Frame is mostly UNDER the truck. What the axles bolt to, the big, square tubes of metal, and so on. Body is the cab, the bed, and so on. Generally the cab, engine compartment, etc, sheet metal is grounded. Not always, like the bed mentioned above, but you get the idea. You need bare, clean, metal to connect the black lead to. An unpainted screw into the cab's metal is a good example. That's a great ground. You can verify it, should you desire. Pull off both battery leads, set your meter to a low Ohms scale, touch one lead to the screw you want to check, and the other to battery's negative lead. If it reads about zero-ish, like below 0.01, it's a good ground. Quite often, there are unused screw holes you can stick your black lead into, so you don't have to hold it constantly. As mentioned, though, make sure there's no paint, etc in it.

Anyway, Good luck here on out.
Pat☺

 

Hi Pat,

Yes, early on I had swapped the "back door open" light with the CEL. I knew that back door open light was working because it had been on all the time. Anyway, I tried swapping bulbs around again and it fixed it! One thing I wonder, though.. I have been reading other threads and it talked about polarity with the bulbs. If the bulb doesn't work, flip the connector around and try it the other way. That may be just talking about LED bulbs though, not sure if it is referring to incandescent ones. Maybe that could be what happened. In the short term, all I care about is the darn CEL does come on when you click the key on! And then it goes out once the truck starts. I drove it around a little today but CEL did not come on. So tomorrow, I have an appointment with the state emissions folks to see if I can get an emissions waiver. In order to get the waiver: 1) CEL must work, 2) no black smoke from exhaust, 3) proof of spending at least $700 on repairs to try to get it to pass emissions. So now I SHOULD have all my ducks in a row. Wish me luck! Once this is all done, I am going to try to mess with bulbs again and see if I can get them all working.

Thanks for all the other kind words, Pat. I appreciate your patience, ideas, and how you explain things using small words so that I can understand!

 

Incandescent bulbs have no polarity.

Why do you need a waiver? How far out are you? While $700 spent unsuccessfully may be the sign to "give up," I'm sure you'd rather it worked correctly. And you've got no codes, which is a plus.

DO keep an eye on it One problem with intermittent failures is that all your bumping around might have temporarily reconnected something. If you have a loose connection somewhere, it might just jiggle itself back "open" over time.

Keep your fingers crossed.

 

Incandescent bulbs have no polarity. - GOOD TO KNOW, thank you!

Why do you need a waiver? How far out are you? While $700 spent unsuccessfully may be the sign to "give up," I'm sure you'd rather it worked correctly. And you've got no codes, which is a plus. - So in Colorado, if you spend $700 at a qualified shop but it still fails emissions, then they will give you a waiver on having to pass, so long as the CEL works and no black smoke. You are RIGHT, I want the thing to work! At least this buys me some time. I can get plates on it and be legal. And then have more time to figure it out. I think I have no codes because I removed the negative battery cable a couple of times. My hope is to drive it around and see if it will trip a code that will give me a clue of why the CO is high.

DO keep an eye on it One problem with intermittent failures is that all your bumping around might have temporarily reconnected something. If you have a loose connection somewhere, it might just jiggle itself back "open" over time. - Good point. I definitely do want to get all the lights working on it. That is one of my projects. And then hope to leave it alone and not jiggle anything.

Keep your fingers crossed. - Yep, wish me luck tomorrow! I will report back with what happens.

 

Success! I was able to get the emissions waiver. It is good for 2 years. So now I can get license plates for it! While I was driving it around this morning, the check engine light came on! I was able to jumper the TE1 to E1 and read the code from the comfort of the driver's seat (71). So that will be my next project, trying to troubleshoot that code. Also, I ordered some instrument lights so I am going to take the instrument cluster off one more time, test lights with my multimeter, figure out which ones were bad, and probably just replace all of them. Thanks to everyone who helped me with this!! @2ToyGuy and @scope103 especially, I appreciate all of your input, advice, and knowledge!

 

I do believe you can get LED lights that are direct replacements for the incandescent lights, should last pretty much forever. Might be something to look into.