Brake Lights and Turn signals

[smoothandlow84]

Check the adjustment and or the brake light switch itself. The brake light switch is located under the dash near the steering column base where the brake pedal connects to the firewall. The brake light plunger switch can go bad, the wire connections can come loose easily and I have even seen cases where the plunger sticks causing the light circuit to fail and remain off when the brake pedal is released. Trucks with cruse control have two line switches, one switch has a vacuum hose connection for the kickdown/ cruise control while the other is just a plunger switch.

 

[75gmck25]

Most of the problems you describe are usually related to either bad grounds, or a problem with the turn signal switch in the column.

Every exterior light housing (tali, marker, etc.) has a ground, and there is another larger ground wire one in the harness behind the middle of the back bumper. These wires are usually white.

There are also two black ground wires under the hood, one on each side of the radiator support, which are for the headlights. The one on the passenger side also connects to battery negative terminal.

There is braided ground from engine to frame on the passenger side and another from engine to body in the back of the engine on the passenger side. That back engine-to-body ground is often accidentally left disconnected, since they may have used a valve cover bolt as a ground point.

The other extremely important ground is for the instrument panel. On older trucks the black wire ran to a bolt on the emergency brake mechanism, but on your newer truck I believe they have a dedicated ground terminal somewhere else under the dash.

For every ground point, you need to remove the bolt/screw and wire terminal, sandpaper or ground the metal behind it so it is shiny, and then reinstall it with a toothed/star lock washer. You want that washer to bite into the bare metal.

Bruce

 

[Cuba]

Hey Mike, when describing the tails lights be sure to use the term parking lights or brakes lights.
Parking lights come on when you have the headlights on, brake lights only come on with hazzards, turn signal, or brake pedal. I sometimes find it confusing just using the term tail lights. .. I don't know if you're describing brake or parking lights.

Great job on fixing the 1 issue so far... when checking the brake lights by yourself, it may be helpful to use a 2x4 squeezed in between the brake pedal & driver seat.

 

[Georgeb]

If the rear turn signals work but the brake lights don't. looking at the attached image. perform these checks in the following order:

1. Power at the orange wire on the brake switch.
2. Power on the white wire at the plug for the turn signal switch under the dash on the column with the brakes applied.
3.Power to the yellow and green wires on the plug for the turn signal switch with the brakes applied.

This will help determine if it is the brake or turn signal switch. If it all checks out and neither the brake or turn signals work the problem is between here and the lamps in the rear.

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[smoothandlow84]

My brake light issue... (brake lights would intermittently not work, but turn signals would)...was caused by a bad turn signal switch in the column. These turn signal switches are notorious for going out. Basically, whenever I used the turn signal to turn left, it would not always return to the neutral position after the turn was made (which clicks and sets the switch to the neutral position). This always caused the brake light NOT to light up the next time the brake pedal was pressed. The only way to get both brake lights to work was to manually return the turn signal stalk back to the neutral position after the turn was made.

 

[Cuba]

My brake light issue... (brake lights would intermittently not work, but turn signals would)...was caused by a bad turn signal switch in the column. These turn signal switches are notorious for going out. Basically, whenever I used the turn signal to turn left, it would not always return to the neutral position after the turn was made (which clicks and sets the switch to the neutral position). This always caused the brake light NOT to light up the next time the brake pedal was pressed. The only way to get both brake lights to work was to manually return the turn signal stalk back to the neutral position after the turn was made.

Yeah, that's because the little spring clip breaks in the turn signal switch. OR the cam wears... I was having that issue for the longest time, just too lazy to replace the spring. If that's the case, it's much easier to undo the top of the column to the switch, then just replace the return spring that rides on the cam. Otherwise to replace the whole turn signal switch, you need fish the connector through the column...

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