How do I fix a voltage drop when applying breaks?

Are you sure you want to do that ? Are you guessing that's the problem ? Do you know what DTC'S - diagnostic trouble code's are ?

DTC B2610

The body control module (BCM) applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp switch. When the switch is placed to the desired position, the dimmed voltage setting is applied from the interior lamp switch through the I/P dimming return circuit to the BCM. The BCM applies the dimmed voltage to the I/P lamps supply voltage circuit.
Do you know how to do electrical testing ?
Reconnect the lamp switch assembly.
Disconnect the body control module (BCM) connector C1.
Using a DMM, measure the resistance between the I/P dimming voltage reference circuit and the I/P dimming control circuit.
Vary the I/P dimming switch from full bright to full dim.
Does the DMM, display change?

Did you perform the Diagnostic System Check - Vehicle?
Yes - Go to Step 2
No - Go to Diagnostic System Check - Vehicle
2
Verify that the interior backlighting does not dim.
Does the interior backlighting operate normally?
Yes - Go to Testing for Intermittent Conditions and Poor Connections
No - Go to Step 3
3
Do the instrument panel (I/P) lamps dim?
YES - Go to Step 13
No - Go to Step 4
4
Do the class 2 lamps dim?
Yes - Go to Step 5
No - Go to Step 6
5
Test for a short to battery positive voltage in the I/P lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Yes - Go to Step 14
NO - Go to Step 13
6
Disconnect the lamp switch assembly.
Does all the illumination of the backlight components turn OFF?
Yes - Go to Step 8
No - Go to Step 7

you forgot, does it do that running engine or not.?
ok the main battery is car is doing that.
use a voltmeter, at the battery or even at the CIG lighter port.
12.6v DC, not running. rested. running voltage is 13.3v to 15vdc,

start engine, is rpm above 800 RPM at all times, or more?
if not, the alternator will be too slow, and drop out and when that happens , the lamps will dim. (a 3 volt drop does that)
1: all fuses good
2: battery term lugs clean, not green
3: fan belt to alternator not loose. slipping.
4: charge lamp on dash not ON, running.
5: check engine lamp not on, running (if yes,scan it now)
6: test the battery , batteries are LOW life objects, (die-easy-not-hard)
test the battery , using a load tester or take it in for testing, it's free.
or try a spare battery from another car. do not reverse POLARITY.
this gets the lions share.

engine running or not,,??????
bad battery
or dead charging system.
rusty battery terminals.
check battery voltage parked key in pocket, see 12.65vdc.
if lower , on a warm day the battery is discharged
or at 30F it must be.12.58vdc, rested, if not the battery is discharged
or battery is bad.
if discharged , then charge it.
and fix the bad charging system.
ok you jump start car.
and the battery voltage is 13.3 to 15vdc, if not the charge system is failing, or engine RPM below 800.
if running voltage is below 13.3v the charge system is failing running.

Get a volt meter, start your car and see how many volts your car is producing while running. Should be around 14 volts. May want to watch the meter for a while since your electric seems to fluctuate. Most voltage regulators are internal of your alternator. If you are getting a lot more or less than 14 volts while running, replace the alternator. If it is not charging, voltage will drop as vehicle runs, until battery is dead.

Electrical problems are hard to fix. You need a voltage test for the charging system and a battery test.

The oil light, abs light, are not hooked up to the turn signals. Never heard of balance of lights coming on in that manner.

The heater fan, headlights, and wipers will slow if the charging system can not keep up. Battery light is accurate to show discharge.

Trans shifts can be affected by voltage. Some transmissions use electric solenoids to shift and they mix voltage to get different gears.

I think one of two things may be causing the problem. Either your alternator is weak and not putting out enough current (check with a voltmeter, engine running, look for a minimum of 13.2 volts at the battery), or the heater motor has a short drawing too much current (but if it also happens applying brakes, that may not be the case).
I don't think the starter going out is related to your present problem.

Most likely it is the voltage regulator in the alternator . this is common of a alternator be for going bad, some times this is caused from jump starting.rarely it could be a intermittent short. but it would save a lot of time to have the alternator Thrilley tested or even replaced.it really don't mater about the volt out put.if the reg. is failing .hope this helps .if you want any further assistance feel free to ask.we are here to help.

Check connections to the fan speed resistor module for looseness, and the resistor module itself for heat damage or intermittency.
The resistor module is in the heater fan ducting in the fan airflow.
Alternatively, the fan motor may be faulty (or have worn brushes)- apply power directly to the motor supply connections to ensure it runs ok.

you may have a bad ground where the ground wire attaches to the body. its a black wire and the connector is just below the trunk latch on the inside.

Its not unusual to have a sudden drop of volts. especially if you have something running like your a/c or heater that requires a lot of power to run. it will also do it when your fan kicks in. anything that requires power is going to kick down your voltage. i would not worry about it unless the battery starts to die overnight.