2003 chevy silv, Break light

[Billy J]

Hello, My drivers side break light and the 3rd break light on the cab would some times work and some times not. Now they dont work at all. The bulbs are all ok, even check the wires, I see they tie into a box under the rear of the truck. I unpluged and repluged them and the drivers side still dont work. Can some one please help with this?

[j cAT]

Originally Posted by Billy J

Hello, My drivers side break light and the 3rd break light on the cab would some times work and some times not. Now they dont work at all. The bulbs are all ok, even check the wires, I see they tie into a box under the rear of the truck. I unpluged and repluged them and the drivers side still dont work. Can some one please help with this?

usually the wires /connector at the rear of the vehicle get damaged recheck the wires for abuse..open connector and see if the conn. pins are green...look at the ground points in this area...do the emergency flashes also show this failure??

[Billy J]

No my emergency flashers work fine. I've checked the connections and all are silver no blue or black and the plastic holders are all in place.. What do you know about the rear lamps bussing block? Is it some sort of electrical control unit?

[gremlin96]

try taking a wire with alagator clips, put one end on the frame and the other on on a tail light gound.

chevy is bad about loseing gounds.

[j cAT]

Originally Posted by Billy J

No my emergency flashers work fine. I've checked the connections and all are silver no blue or black and the plastic holders are all in place.. What do you know about the rear lamps bussing block? Is it some sort of electrical control unit?

what I remember is that the bulbs may need replacing as they did not use dielectric grease on the bulbs base....the connector under the vehicle behind driver side tire is also in need of checking and if necessary use a meter to insure you have voltage and ground....measure across wires then measure to body /frame point... you can have an open feed or ground wire..

swap bulbs also ..


the cab light is known for corrosion...

[Hacksaw1968]

If I,m not mistaken I think they have fuses for left and right brake lamps. I,ve seen them blow when a trailer with faulty wiring was attached. check out the fuse block under hood on drivers side.

[sierra99]

I have a 99 silverado and had my left rear lights not work. It started off to be intermittent and finally went out. I replaced the bulbs and that did not work. Finally after doing some testing, I found a bad circuit board under the bed close to the spare tire. One harness feeds the board and then your left rear, right rear and 3rd brake fight harnesses feed from that. Mine was bad at about 35,000 miles.

here is what I did to check my ckt board:

Get a voltage light.

Have somebody apply the brakes

check the right side connector for voltage at the pins (after removing right side wiring harness)

Go to the left side and check to see if you are getting voltage on the same pin as the right side.

If you get no voltage on either side, pull the harness closest to the front of the truck. This should be the feeder harness. Check for voltage there.

Post results..

[sierra99]

I have a 99 silverado and had my left rear lights not work. It started off to be intermittent and finally went out. I replaced the bulbs and that did not work. Finally after doing some testing, I found a bad circuit board under the bed close to the spare tire. One harness feeds the board and then your left rear, right rear and 3rd brake fight harnesses feed from that. Mine was bad at about 35,000 miles.

here is what I did to check my ckt board:

Get a voltage light.

Have somebody apply the brakes

check the right side connector for voltage at the pins (after removing right side wiring harness)

Go to the left side and check to see if you are getting voltage on the same pin as the right side.

If you get no voltage on either side, pull the harness closest to the front of the truck. This should be the feeder harness. Check for voltage there.

Post results..