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I've got a seatbelt light that stays on but its very dim. When my belt isn't fastened its on normal, after its clicked its dim. Its only really noticeable in the shade or at night.
 

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My guess is a leaky transistor of the seat belt light or LED. If so, this is a component of the instrument cluster; not something outside. So, you can consider removing and cleaning the instrument cluster circuit board and hoping it will fix it... or the transistor for that light (in the cluster) might be stuck lazy and might even get worse. Get some sunglasses and wear them at night, and pretend the light is not dimly On.

I am guessing that the instrument cluster receives that seat belt On/Off signal via digital data... so the "half-on" or "half-off" light problem is within the instrument cluster. Punch it or use a hammer? Or, maybe some other techniques?
 

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I don't know if it's worth disassembling the seat belt latch for this or not. It's more likely that at some point a drink was spilled or splashed or even dripped on the seat belt latch, and now the switch in there is sticky. That's causing a partial connection when it should be open. You'd have to remove it, disassemble it, and arm yourself with Q-tips and alcohol. That might not even be it because it could be an issue with the wiring to the latch switch itself. Those are usually grounds, and the switch makes the connection to the ground through the light, but if that wire is touching, insulation rubbed off, etc somewhere, then it can give that dim signal like you're seeing.

I'd start by disassembling the latch since typically wiring doesn't get damaged (unless you own a hatchback).
 

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I agree with whynotthinkwhynot, where anything is possible, and cleaning that belt latch could fix it. However, my curiosity got the best of me so I opened my 2004 wire diagram book and sniffed around. Most of this post is to satisfy my own curiosity and may not help the OP much.

In my prior post, I had assumed the seat belt latch (on or off) signal was provided to the instrument cluster via digital ISO or SCP bus. I was wrong.

Key pieces of this puzzle were shown in 60-1 (Instrument Cluster) and 66-1 (Warning Devices) wire diagrams.

The first thing of interest is that the seat belt latch is not a mechanical switch, so it does not have traditional mechanical contacts to clean. It is a Sensor, so it is likely a proximity or Hall-effect type of switch. Either way, the end result is once the seat belt is latched, the sensor completes/closes a circuit and the GEM or the Restraints Control Module (RCM) detects this.

The GEM receives the seat belt latch signal only if your car is built in Mexico or was built for the Mexico region. No where in the book does it clarify what the "Mexico" reference means. For all other cars, the seat belt latch circuit goes directly to the RCM, and does NOT go to the GEM.

Once the RCM receives the seat belt latch signal, this info is passed onto the GEM via digital data on the ISO bus. In response to this digital message, the GEM has a wire that connects directly to the instrument cluster seat belt caution light bulb, and will turn it On or Off; using the typical method of a "circuit ground" located within the GEM. This circuit ground is controlled by a Transistor Logic (TTL) type of circuit within the GEM.

In my first post I talked about the possibility of a "lazy or leaky transistor" within the instrument cluster. What I found today was; if there is a leaky transistor causing the OP's lamp to stay partially-On, that transistor is not located within the instrument cluster, it is located inside the GEM.

Also, just to clarify, when I say transistor, this does not mean a stand along device. These transistors are more likely located within integrated chips. IC chips can have failed or leaky transistors.

After all this babble, go ahead, get some Carb or electrical contact cleaner and spray-out that seat belt buckle latch. Proximity switches get dirty too! The system however is a On or Off thing; and is also a digital-0 or digital-1 thing; not a half-On, half-Off thing.

Good Luck!
 

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I have the same issue, just started 2 days ago....every once and awhile while driving it will also flicker as does the security light but not as much.
it seems to me as it may be a ground issue or something in the cluster, will a tach cluster work in a non tach cluster, and does a replacement cluster need to be programed for the car or does the ECM contain all the info to be transferred to the cluster?
 

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tach cluster will work in place of a non-tach, need to match engine types & model versions, mileage stays with the cluster.
 

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it seems to me as it may be a ground issue or something in the cluster,
Correct! So before you replace the cluster, you should consider removing it, opening it up, and cleaning the circuit board with a soft toothbrush and maybe some electrical contact cleaner. There are a couple/several success stories here and across the web of people fixing this or similar symptoms after cleaning the circuit board.

Here is one of many search results.
http://www.focusfanatics.com/forum/showthread.php?t=188957
 

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Reason I asked about the tach cluster, is because I happen to be the local focus collector here, and just bought number 5 last week for parts. It is an 05 auto with tach and my one I am trying to fix is an 05 man without tach. Both are 2.0l. Instead of cleaning mine, I'd just as soon put the tach cluster in.

Although today, about 4 days later, it seems to be alot dimmer, almost impossable to even see it is on.
 
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