RPM drop on electric load

Hello friends,
New member here.
My car: Jimny 2001 Japan made.
My problem:
With engine at idle, when depressing brake pedal (brake lights on) or when lifting both windows in the same time, the RPM drops from approx 800 rpm at idle at about 350-400 RPM and the car shakes a bit, like trying to stall. The issue is more persistent in cold weather.
I have cleaned the ground points (engine bay and car interior) but still have this problem.
Any suggestions are welcomed.
Thanks in advance!

I'm sorry for posting in the wrong section, maybe the admin will move it to Jimny technical. Thanks!

Clean the idle control valve, check the crankcase pressure valve is working and replace if necessary.

I forgot to mention but I have cleaned the IAC valve an the PCV valve is brand new (and working).
I've checked the alternator on professional tester and it is in good condition. Battery is brand new.
I am a former Suzuki Samurai user (drove it for almost 8 years) and I'm familiar somewhat with these engines.
It seems that ECU doesn't detect the applied electric load and doesn't increase engine RPM accordingly.
If I use the headlights (even on strong beam), RPM increases for a moment, then drops to normal idle.
Thanks!

The ECU should detect electrical load, you need to check the inputs to the ECU.

Rhinoman wrote: The ECU should detect electrical load, you need to check the inputs to the ECU.

The ECU detects electric loads (headlights, heater fan). RPM drops only when applying brakes or when I lower or close both windows in the same time.
Maybe I have missed a ground spot. Are there any ground connections under the rear bumper or around tail lights?
Thank you!

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The brakes use the engine's vacuum so pressing then will normally cause the idle to fluctuate.

Busta wrote: The brakes use the engine's vacuum so pressing then will normally cause the idle to fluctuate.

I agree that it should be a small fluctuation but at 300-400 rpm the engine shakes and it creates the feeling it will stop in a second. It doesn't stop, but I doubt this happened when the car was brand new.
So maybe the brake booster is the cause?
How do I check it?

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Problem solved, new wire between generator and 80A fuse in the engine fuse box.
For details, everyone is welcomed.
Cheers!

Break in the wire or bad connection?

Can you send me some more details on what you did or upload some pictures pretty please? I think I may have the same issue as you!

Hello same problem. Plss help mo
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