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Damaged components in ECU

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New Member
Hi Guys,

I am trying to repair the ECU of my car.

Recently I have tried to replace regular dashboard bulbs with led ones. As a result I have damaged my computer and check engine lamp stopped working. The reason is because one of the leds is short-circuited. All other functionalities work properly. I have found a damaged transistor and a damaged resistor inside the ECU. The problem is that the transistor doesn't have any identification and the resistor is burnt and one of the colors is difficult to read. I think that the driver transistor might be MOSFET, but I am not sure.
I will be greatfull if someone could help me to identify the transistor and the value of the resistor or some analogs maybe.

Thanks in advance. Nikolay


Well-Known Member
You are likely correct about the transistor being a Mosfet, the type probably won't be anything special, just general purpose 500mA type thing if it's only driving the MIL lamp. Your best bet would be to find an identical ECU for a comparison, or even a couple of really good photos of the board at a stretch :)


New Member
Thank you very much for your help. :)
Here are the photos I have. The quality is not very good but I hope they will help. Bad components are Q23 and R242 at the center of the board.
Can you also please suggest a value for the resistor? And by the way what is the purpose of this resistor (to work like fuse or to limit current through MIL and MOSFET)?


Okay a couple of things before we proceed. Make, model, year of vehicle and engine size to start with. if you have a part number for the ECM, that would be helpful and perhaps the manufacturer of the ECM. Delphi, Toyota ????
Next, can you show pictures of what it is you did to get you to this point? I am assuming you tried to replace incandescent lights with LED's and therefore changed current and resistance levels in the circuit you are ow trying to repair. LED's work at very low voltage and current in comparison to incandescent lights, just for future reference.
Lastly, the pictures you have on here are not comprehensible. Try to get a good clear picture from above of the entire board, and then in close on the section that is damaged. Then we can help you.


Well-Known Member
Most Helpful Member
Look for things that might be similar. i.e Q6 and it's associated resistor. what are the markings on Q6?
Look at the values of the resistors. See if they are similar on other ares of the board.

That's what I can give you as a hint for now.


New Member
The car is Mitsubishi Carisma 1.6/96. The part number of the ECM is MD329097 E2T63285 and the manifacturer is Mitsubishi Electric.

The LEDs I use are packaged with resistor inside and they are calculated to replace incandescent lights without need of other modifications. At the beggining I used white LEDs and all lights worked fine but some of the lights because of the color filtration in the dashboard had strange colors. For example yellow looked orange and red looked purple. So I decided to change them again with color LEDs (green, yellow, red, blue) to remove this effect. I put all new LEDs in places but the check engine one didn't light on. I replaced it with original bulb but it didn't work anymore. I decided to check resistence of all LEDs and I found that one of them was short- circuited inside (the one I used for check engine light). This short-circuited LED led to damage to the board. After that I opened the ECU, traced pin 36 which is connected with check engine lamp and found the problem components.

I will see if Q6 and Q5 have any markings and also resistors.

I will try to get a better photos of the board this weekend and post them here. Thanks for your help.
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