A bad ground.
its on the left hand side of the steering wheel for the turn signal
You have a turn signal light-bulb out .
The turn signal switch is on the left.The turn signal switch is on the left.
1989 silverado left turn signal set applying brakes causes the left turn signal to dim and the two right rear tail light bulbs to alternate brightly? Further problem occurs to same truck - in Park and brakes not applied -- if head lights are on turn signal flash slows right down almost to a stop and becomes very dim
with turning the left signal light on.
the left turn signal light on my ridgeline does not work but the right side works
Could be turn signal flasher
May be a problem with the switch in the steering column
You need to twist the turn signal switch.
Bulb is out.
The wiring in the left turn signal circuit shorted out. Or it can be the socket that the left turn signal light screws into is shorted out. Look for bare wires or corrosion.
On the left Turn signal handle