Questions on Instrument cluster and wiring diagram?

Tiny
TONSING
  • MEMBER
  • 2022 SUZUKI BALENO
  • 1.2L
  • 4 CYL
  • 2WD
  • MANUAL
  • 32,900 MILES
I have 2 questions on instrument cluster/android stereo and symbols on wiring circuit diagram.

1. In the 1st of the 2 attached diagrams, there are 2 fuses 5amp and 10amp which go directly to the instrument cluster and appear to supply all the same components. Now, what is the purpose of these 2 separate fuses? Does it mean when 5amp is blown, the instrument cluster will still get power from the 10amp or vice versa?

2. In the 2nd diagram, the red marks are a npn or pnp transistor? So also, what are the blue marks which has SQUARE empty box? What does this box represent?
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Sunday, May 11th, 2025 AT 7:22 PM

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Tiny
STEVE W.
  • MECHANIC
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Each fuse powers different parts of the panel. For instance one may be a power feed that goes to the illumination while the other powers the processor circuitry. One may also be switched power and one full time, that isn't shown in the diagram.
Boxes are connection points. Those are both shown as PNP, however that doesn't mean that they actually are the type used in that application, they just use it to show it is a transistor switched circuit instead of a relay. A quick tip on NPN vs PNP = Not Pointing iN represents NPN. Points iNward Pointing = PNP
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Sunday, May 11th, 2025 AT 7:42 PM
Tiny
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In continuation of these diagrams, I have the following questions.

My Maruti Suzuki Baleno/Glanza has some weird behaviour.

Until today, the brightness of the instrument cluster and the stock android display are always set to full. And, the intensity of Brightness is 100 percent. This is normal.

Today, to my surprise, I noticed that the brightness in both the said components are decreased say 80 percent although all settings remains the same. I didn't change any settings.

There's no warning signs in the instrument cluster, and all settings knob on it are working perfectly. However, the brightness intensity is about 80 percent only even if the brightness level is set to full. Same goes to stereo display settings.

In fact, the ambient light sensor is working perfectly. No issues in starting the car. No other issues.

How to get back to 100 percent brightness intensity? Why it is dimmer even though brightness level is full?
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Sunday, May 11th, 2025 AT 7:55 PM
Tiny
STEVE W.
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As it is both the stereo and the dash that eliminates it being just a fault in the driver circuit in one item. Instead it would be in the lighting control for the displays. I would start by looking at the control that changes the brightness. If it is a simple potentiometer see if the brightness returns if you bypass the dimmer. If it does the control has failed. If it doesn't then there is likely an issue in the body module that is causing the dimmer lamps. You may want to check for any hidden menus as well. For instance many Chrysler products have a menu in the "radio" that allows the user to set a maximum brightness that is independent of the illumination dial.
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Monday, May 12th, 2025 AT 7:34 AM
Tiny
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Follow ups of the 2 diagrams, I confirmed that the 5amp is always hot, and the 10amp is hot when key at on or engine running.
If so, then, how these 2 voltages are controlling the different LEDs.
How does 2 voltages work?
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Monday, May 12th, 2025 AT 8:10 AM
Tiny
STEVE W.
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They simply provide power to the systems, not just the LEDs. That power goes into the different modules and into voltage regulators and then it is sent to the various items that need power. The 5 amp is likely the one that is used to hold the memory items, and the 10 amp is used for active power for the remainder. So, the power for the gauges and displays as well as the lighting are all powered off it. For the illumination that would be a regulator, then a controller for the brightness and the LEDs in the array. Those parts would be in both of the modules. As such we know the issue isn't likely to be something in the "radio" or the instrument panel as they do not share the same components internally but they both are seeing the reduced brightness. So, you need to look at the components they share. The only obvious one is the dimmer control and its tie into the CAN network. A scan tool connected up might show you the brightness level in the body control module.
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Monday, May 12th, 2025 AT 2:03 PM
Tiny
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So, you are suspecting a single common PWM Dimmer Controller to be present inside the BCM?

And, once the scanner is connected, and if the brightness is set to full on the scanner, but still the brightness on the instrument cluster as well as the stereo display stays at 80 percent, does this points to defect or error in the Dimmer Controller?
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Monday, May 12th, 2025 AT 7:22 PM
Tiny
STEVE W.
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There will be a PWM driver in the dash that controls the LEDs, but it will be controlled through the data bus signal from the BCM to it. It will be related to that. If the scan tool shows 80% and using the dimmer only changes it from 0-80% then the issue is in that circuit.
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Monday, May 12th, 2025 AT 7:35 PM

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