TM 10-3930-659-20 6-30. BRAKE LIGHT SWITCH REPLACEMENT. 3. Disconnect two under cab wiring harness connectors (7) from brake light switch (6). 4. Remove brake light switch (6) from left brake valve (5). b. INSTALLATION 1. Install brake light switch (6) on left brake valve (5). 2. Connect two under cab wiring harness connectors (7) to brake light switch (6). FOLLOW-ON TASKS: • Install front and left side cab skirts (see paragraph 14-6). TA707812 6-126