What does the Met-B fuse Control

I have a random parasitic draw and I have narrowed it down to the Met-B fuse. Sometimes it happens sometimes it does not.

What does Met-B control specifically so I can dig deeper into the root cause?

 

https://imgvehicle.com/toyota/tundra-ii/fuse-box

MET-B is Gauges and Meters. Now what you’d need to do from there...

 

That is so weird because I pulled the Met-B fuse and my dash still works....not sure why??? Gauge and cluster appear to work fine.

Anyone know why?

 

Strange that the gauges and meters still work when I pull Met-B. I do see that there is a secondary fuse 28 labeled Met which also controls the Gauges and Cluster.

Anyone a Toyota expert that could tell me what specifically the Met-B controls in the cluster or have a wiring diagram?

I appreciate all the help. I did look into a refurbished cluster and it is $414...ouch

 

I would really appreciate the help on this question, especially before I pull the trigger on a new instrument cluster!

 

Do you have any aftermarket accessories that may have tapped something in or around the instrument cluster? If not, I’d say that the cluster itself is probably the issue. You can pull the cluster out and inspect, not sure the process on yours, but there’s not much to it on my 2018.

As for the replacement, maybe check pick and pulls in your area or maybe eBay. $400 is a lot of cash...

 

I do have some aftermarket accessories but nothing is tapped into the instrument cluster. I have a tailgate backup camera that uses the OEM wiring on the passenger side kick panel, some aftermarket fog lights that are properly relayed and fuse tapped under the dash and my tailgate Pop-N-Lock that is fused using the passenger side kick panel. I've unplug most of these and the drain is still there so I am thinking it is probably something in my instrument cluster.

The probably with a bone yard cluster is the mileage. I would need to get that corrected, which seems to run about $150.

 

How much of a draw are you talking about here?

 

Just under 200mA. If I pull the Met-b fuse, it drops to just under 40mA.

 

I wouldn’t spend any time chasing that, a draw that low is perfectly acceptable in the world of today’s electronics.

I assume your original issue is / was a dead battery? Has the battery been load tested? Does the truck sit unused for long periods of time?

 

According to this article, you should probably keep at it ..... https://www.optimabatteries.com/experience/blog/what-is-normal-for-parasitic-draw

 

I would disconnect the instrument panel and then measure the draw. If it stays the same without the panel connected then at least you can eliminate that component.

 

Yeah 200mA is too high. It will drain my Northstar in a week if the mysterious parasitic drain happens.

Does anyone have access to the Fuse schematic or anyone a tech who has seen a tundra cluster go bad? It seems to be a rare occurrence.

 

https://www.tundras.com/threads/ultimate-wiring-diagrams-collection.81448/#post-2058879

@RainMan_PNW put together a ton of wiring diagrams. Might be something useful in that thread.

 

Perfect. Thanks a bunch. I just looked at the 2010 wiring diagram and the Met-b fuse layout is on page 286. It looks like the fuse feeds the combination meter/dash display directly. Maybe I am pulling the dash display tomorrow....

 

Just saw I was tagged. I don’t have that specific EWD pulled down, but it is important to go through all of the system diagrams and search for that fuse. It MAY be tied to more than one thing, or you may see more than one fuse on the same circuit. That might also help identify what specifically inside of the gage cluster is fed from that fuse. There are more than a few places where they will have two different fuses feeding a single circuit, with a non-switched (battery) circuit feeding the main load and then switched (ACC or IGN) circuits feeding the relays. I know that there is some draw at all times from ECU and things like the security light, but it shouldn’t be much.

Good luck!

 

200ma is normal while everything’s still freshly turned off. Now let the truck sit untouched for 15-20 minutes. and check the draw, it should drop.

if draw continues, the EWD will show everything that fuse powers, start unplugging things one by one till you find the “cause” and go from there

 

Thanks everyone. I went through the 800 page wiring diagram last night. I did find that the Met-b fuse feeds not only the instrument cluster but also the relay for the horn on security and the security light. The 200mA draw occurs after the truck is in sleep overnight, so definately not normal and completely random. My next step is the unplug the gauge cluster and see what happens. Looks like I will have to leave the trim off while I drive the truck as I may need to plug it in and take it off when I park it for the night.

 

No aftermarket remote start or anything correct? I’ve never seen a cluster cause a higher than normal draw. But anything is possible

what year is the truck?

 

IF you continue to have a draw with the cluster unplugged, i wouldnt not be surprised if the junction block (aka the fuse block) is really the issue.

 

Just wanted to respond to the questions. Yes it has an aftermarket remote start, however, I completely removed it two months ago and the same 200mA draw occurs. So, that is not the issue.

I did however study the wiring diagram and found two paths for the Met-b fuse. One goes from the battery through the Met-b fuse directly to the instrument cluster. The second goes from the battery, through the Met-b fuse and into the Security horn relay in the fuse box under the hood.

So as a first step, I have pulled that relay and will be leaving it out for now. I'll drive the truck and see if the draw continues.

Anyone know where the Security horn is on the Tundra?

 

The MET-B fuse also powers the accessory plug in the console. Make sure nothing is plugged in there or tapped into there to pull power.

 

Nope nothing is plugged into the console or rear seat plug.

 

Just a quick update of some further trouble shooting I am doing. This weekend I did the following:

1) Unplugged my dashcam from the 12V accessory outlet and left it unplugged
2) Removed the security horn relay (which is directly fed by the Met-B fuse) from the fuse panel on the driver side fuse box.
3) Unplugged and left my fuse tap for the rear DVD player undone.

With that, I drove the truck last night to grab dinner. Let it sit overnight. Saw this AM the battery was down to 40% from 75% yesterday. I immediately checked the Met-b fuse and sure enough it was showing 40mV flowing across the fuse. I then probed all the fuses inside the truck and didn't have any draw on them.

So, I pulled the Met-b fuse and inserted it again. The mV draw went from 40 mV across the fuse down to 0 mV so something is definitely stuck on and drawing power. I'm really starting to think it has to be the dash display.

So, the only two things that may be suspect are:

1) Relayed aux LED lights in the front of the truck. These are powered direct off the battery via a relay, the proper way.
2) My Pop N Lock for the truck bed tailgate.

Anyone have any thoughts?

 

Always start with removing any aftermarket parts. Put your DVM into DC current measurement mode and put it in place of the fuse to measure current draw, then start removing your aftermarket accessories one at a time, and see if the current suddenly drops. There's no need to kill your battery overnight as some kind of diagnostic to see if what you're doing is working. You should have a trickle charger on your truck until you get this figured out.

 

I have DVM with Amp clamp for dc power so that is not an issue.

the truck is on a battery tender.

I will chase down my other accessories and report back