As so as i replace the brake light fuse and step of the brake it blows i've replace the brake lamp switch and check wiring at the switch and and the rear lights all look fine what next

Lexus? car? a USA car?
well park lockout works off of BRAKE lamps good.
so you must fix, brake lamps first
and the fuses for brake lamps checked.
Fuse F11 is blown
or brake lamp switch is bad.
if fuse blows again the stop light wring or a lamp is shorted.
got trailer hitch wiring mess at the rear?

Does the fuse blow before or after you step on the brake? If it blows only after you step on the brake, and voltage from stop lamp switch only goes to rear brakes and not through multifunction switch. If only one connector at the rear for brake lamps, take connector loose, step on the brake, if the fuse still blows, the problem is before the connector. You could Use new wire from brake switch feed, when brake switch is activated, to the rear brakes. Leave pigtail at both ends, splice in new wire, You could let new wire just lay on the ground, for testing, from brake switch to rear brakes. If the brakes work and doesn't blow the fuse, Make the new wire permanent and route the wire properly. Just my opinion. I don't have wiring diagram for your model year.

Do you know how to test using a DVOM - digital volt ohm meter ? Is there B+ voltage going into the brake light switch ? An coming out when the brake pedal is pressed ? What fuse's ? There is only one fuse for the brake lights !
The BRAKE SW fuse in the RH I/P fuse block supplies battery positive voltage to the normally-open stop lamp switch. When you press the brake pedal the switch contacts close and battery positive voltage is supplied to the left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The left and right stop lamp along with the CHMSL are grounded at G302.
Do you know about the right insturment panel fuse box ?
Stop Lamps Inoperative
Step
Action
Yes
No
Schematic Reference: Exterior Lights Schematics
1
Did you perform the Lighting System Diagnostic System Check?
YES - Go to Step 2
NO - Go to Diagnostic System Check - Lighting Systems
2
Press the brake pedal.
Do all of the stop lamps illuminate?
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 3
3
Are all the stop lamps inoperative?
YES - Go to Step 4
NO - Go to Step 7
4
Inspect the BRK SW fuse.
Is the fuse open?
YES - Go to Step 14
NO - Go to Step 5
5
Disconnect the stop lamp switch.
Using a test lamp connected to ground, probe the battery supply voltage circuit of the stop lamp switch connector.
Does the test lamp illuminate?
YES - Go to Step 6
NO - Go to Step 13
6
Install a fused jumper between the battery supply voltage circuit and the stop lamp switch signal circuit of the stop lamp switch connector.
Do the stop lamps illuminate?
YES - Go to Step 12
NO - Go to Step 17
7
Determine if the center high mounted stop lamp is inoperative or the stop/turn lamps are inoperative.
Are the stop/turn lamps inoperative?
YES - Go to Step 8
NO - Go to Step 9
8
Do the turn lamps operate normally?
YES - Go to Step 17
NO - Go to Turn Signal Lamps and/or Indicators Inoperative
9
Disconnect the center high mounted stop lamp.
Using a test lamp connected to ground, probe the stop lamp switch signal circuit of the center high mounted stop lamp at the harness connector.
Press the brake pedal.
Does the test lamp illuminate?
YES - Go to Step 10
NO - Go to Step 15
10
Using a test lamp, probe between the stop lamp switch signal circuit and the ground circuit of the center high mounted stop lamp with a test lamp.
Press the brake pedal.
Does the test lamp illuminate?
Go to Step 11
Go to Step 16
11
Inspect for poor connections at the harness connector of the center high mounted stop lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 20
Go to Step 19
12
Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 20
Go to Step 18
13
Repair a open or high resistance in the battery supply voltage circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 20
--
14
Repair a short to ground in one of the following circuits:
• The battery supply voltage circuit of the stop lamp switch
• The stop lamp switch signal circuit of the stop lamp switch
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 20
--
15
Repair a open or high resistance in the stop lamp switch signal circuit of the center high mounted stop lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 20
--
16
Repair an open or high resistance in the ground circuit of the center high mounted stop lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 20
--
17
Repair an open or high resistance in the stop lamp switch signal circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 20
--
18
Verify the stop lamp switch adjustment. Refer to Stop Lamp Switch Adjustment . If OK, replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .
Did you complete the repair?
Go to Step 20
--
19
Replace the center high mounted stop lamps. Refer to High Mount Stop Lamp Replacement .
Did you complete the repair?
Go to Step 20
--
20
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2

DTC B2550
When the body control module (BCM) receives a signal requesting to illuminate the backup lamps, battery voltage is sent directly from the BCM through the backup lamp supply voltage circuit to the backup lamps.
Voltage for the backup lamp supply voltage circuit as well as the courtesy lamp supply voltage circuit is from the left instrument panel fuse block TBC 2B 15-amp fuse directly through the BCM to these circuits.

Brake lights or do you mean tail lights ?

Stop Lamps Always On
Did you perform the Diagnostic System Check - Vehicle?
YES - Go to Step 2
NO - Go to Diagnostic System Check - Vehicle
2
Depress the brake pedal.
Does the system operate normally?
YES - Go to Testing for Electrical Intermittents
No - Go to Step 3
3
Disconnect the stop lamp switch.
Do the brake lamps go out?
YES - Go to Step 6
No - Go to Step 4
4
Remove the CHMSL fuse.
Do the brake lamps go out?
Yes - Go to Step 7
NO - Go to Step 5
5
Remove the STOP fuse.
Do the brake lamps go out?
YES - Go to Step 8
NO - Go to Step 9
6
Inspect for poor connections at the harness connector of the switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.
Did you find and correct the condition?
YES - Go to Step 11
NO - Go to Step 10
7
Repair the short to voltage in the CHMSL supply voltage circuit. Refer to Wiring Repairs.
Did you complete the repair?
YES - Go to Step 11
--
8
Repair the short to voltage in the stop lamp switch signal circuit. Refer to Wiring Repairs.
Did you complete the repair?
Go to Step 11
--
9
Repair the short to voltage in the stop lamp supply voltage circuit. Refer to Wiring Repairs.
Did you complete the repair?
Go to Step 11
--
10
Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement.
Did you complete the replacement?
Go to Step 11
--
11
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3

If you keep blowing the brake fuse than you have a short in the system. Unplug the brake switch. Install a new fuse. If it did not blow than the problem is after the brake switch. Next unplug the turn signal switch, then plug the stop light switch back in and press the brake pedal. Did the fuse blow. If not than the wiring is good in between the two switches. With the turn signal switch disconnected use a jumper wire in between the light green wire (power from the brake switch) and the orange with light blue wire (power to the right brake lamp). If the fuse blows than there is a short in the right side brake circuit between the plug in and the rear socket assembly. If the fuse does not blow than jump from the light green wire to the Light green with orange wire (power to the left brake lamp). If the fuse blows than the problem is in the left hand brake wiring circuit.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

You have a short to ground in the circuit, could be in one of the lamp sockets or in the wiring harness.

Stop Lamp Circuit Description
The STOP HAZ fuse in the IP junction block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to the center mounted stop lamp (CHMSL) and both left and right stop lamp assemblies. The left stop lamp is grounded at G304 and the right stop lamp is grounded at G304.

Check the ground ! Testing an not guessing is the way to find the problem . Do you know how to test automotive electrical systems an circuits using a DVOM - digital volt ohm meter ? How to use an read a wiring diagram to pin point testing areas in a wiring harness ?
Basic Electricity for Service Techs Ohm law Current Flow Opens Shorts
How to Use Multimeter to Troubleshoot Common Problems
Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia

Stop Lamps Inoperative
Step
Action
Yes
No

2
Inspect the 20 Amp STOP HAZ fuse.
Is the STOP HAZ fuse open?
YES - Go to Step 11
NO - Go to Step 3
3
Use a test lamp in order to backprobe connector C1 of the brake switch connector between terminal A and ground. Refer to Circuit Testing in Wiring Systems.
Does the test lamp light?
YES - Go to Step 4
NO - Go to Step 5
4
With the brake switch closed, Test for positive battery voltage at terminal B of connector C1. Refer to Circuit Testing in Wiring Systems.
Is voltage present?
YES - Go to Step 6
NO - Go to Step 7
5
Repair the open or short to ground in the Fuse Output-Battery between the fuse block and the brake switch. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
YES - System OK
--
6
Use a test lamp in order to backprobe the turn/hazard headlamp switch assembly connector C2 terminal A and ground.
Depress the brake pedal.
Does the test lamp light?
YES - Go to Step 8
NO - Go to Step 9
7
Inspect the adjustment of the brake switch. If the adjustment is correct, replace the brake switch.
Is the repair complete?
YES - System OK
--
8
Replace the turn/hazard headlamp switch assembly.
Is the repair complete?
System OK
--
9
Repair the open in Stop Lamp Switch Output between the brake switch and the turn/hazard headlamp switch assembly. Refer to Wiring Repairs in Wiring Systems.
Is the repair complete?
System OK
--
10
With brake switch open test terminal A of the brake switch for continuity to ground. Refer to Circuit Testing in Wiring Systems.
Is ground present?
YES - Go to Step 11
NO - Go to Step 12
11
Repair short to ground in Fuse Output-Battery Circuit. Refer to Wiring Repairs in Wiring Systems.
Is repair complete?
System OK
--
12
Test the Stop Lamp Switch Output Circuit for continuity to ground. Refer to Circuit Testing in Wiring Systems.
Is ground present?
YES - Go to Step 13
NO - Go to Step 14
13
Repair short to ground in the Stop Lamp Switch Output Circuit. Refer to Wiring Repairs in Wiring Systems.
Is repair complete?
System OK
--
14
Test terminals F,G,B and C on the Hazard Warning Switch for continuity to ground. Refer to Circuit Testing in Wiring Systems.
Is ground present?
Go to Step 15
--
15
Repair short to ground in suspect CKT. Refer to Wiring Repairs in Wiring Systems.
Is repair complete?
System OK
--

there is a short circuit in the brake light wiring it could be in the lamp holders them selfs pull off the wires to the brake lights holders on all the lamps and see if it still blows a fuse if it dose then the short is in the loom not the lights them self's if it dont blow a fuse hook up one light at a time untill it starts to blow fuses again the last light to be hooked up that blows the fuse is the faulty light

I had the smae problem, i replaced the tail light circuit board and the problem was solved.

Check Trailering Wiring