Hi and thanks for using 2CarPros. Com.
The signals/brake lights use the same bulb. It is a dual element bulb. When the signals flash double time, that indicates a bulb needs replaced. The manufacturer has designed the double time speed as an indicator. Since they are both doing it and the brake lights do not work, it sounds like the bulbs need replaced.
Here are the directions for replacement on your vehicle. The attached pictures correlate with these directions.
TAIL/TURN SIGNAL LAMP REPLACEMENT
1. Make sure the headlamp switch is in the OFF position.
2. Lower the endgate or open the cargo doors.
IMPORTANT: Z-71 Tahoes have a rear tail lamp cover. Once the cover is installed removal will result in breakage of the cover.
3. Remove the 2 screws retaining the tail/turn signal lamp assembly to the body.
4. Rotate the tail/turn signal lamp assembly from the vehicle.
5. Disconnect the electrical connector from the assembly.
6. Identify the bulb in need of replacement.
- The top bulb is a parking lamp.
- The center bulb is a parking, brake, and turn indicator lamp.
- The lower bulb is a backup lamp.
7. Pull the bulb straight out by the tabs on the base of the bulb in order to remove the bulb.
1. Push the bulb straight into the lamp assembly in order to install the bulb.
2. Install the lamp base to the lens assembly with the 2 screws.
3. Connect the electrical connector.
4. Install the tail/turn signal lamp assembly to the vehicle with the 2 screws.
I hope this helps. Let me know if you have other questions.
Images (Click to enlarge)
Thursday, October 18th, 2018 AT 6:09 PM