Turn signal problems

[telbdm]

98 GMC Sonoma. left front and rear flashers work fine during the day. At night, when you turn on all necessary light functions, the left front and rear flashers light one time and then do not flash anymore. The right side if fine. swapped flasher bulb in front from left to right side and problem stayed the same, so it doesn't appear to be the bulb. Any ideas? Son bought this truck in Georgia. He moved to Alabama and needs to have this truck pass inspection before he can get a tag for it. This flasher issue will keep him from passing inspection so need to get it fixed asap.

All you GMC Sonoma experts, I beg you for your wisdom. Thanks in advance for all your assistance.

 

[lmleck]

Swap the bulbs in the rear...

 

[OnlySonoma]

Make sure that your alternator is charging your battery enough to power the flashers on top of all the necessary light functions.

Look at the wiring its self to check the condition of the insulation.

Check the connections to the light housing.

Check that the bulbs are the correct bulb type.