Have 1990 gmc. Rt signal quit working, bulb was out. replaced with correct bulb, it lights up but will not blink. Replaced other rt side bulbs since I had extras, all light up but will not blink. Turn signal indicator on dash has been on all the time since the first bulb went out. Left side all work. Any ideas what I can do next? Thanks

 

Turn on the 4 ways and the parking lights: watch both rears, make sure both sides flash the same. Do the same in front. You'll probably find one that doesn't blink correctly, check the ground in that socket. Must be 5 ohms or less to a good clean body ground.

 

Thanks, 4ways all work, but found one parking light doesn't. Has new bulb, so will check ground.

 

Don't have resistance meter, but checked with test light. Connected one end to battery and other to socket ground, and test light worked. Then checked with one end to a good body ground and other end to socket connections and test light worked. now am really confused.

 

Park & 4 ways turned on, and the bulb removed from the socket:

Test light connected to battery positive, touching the probe to the ground terminal in the socket, the test light should come on.

Test light connected to battery negative, touching the probe to the park light terminal in the socket, the test light should come on steady, and the other terminal should flash when the 4 ways are turned on.

 

yes to all. Test light comes on, but when bulb is in, the parking light doesn't work on the rt front.

 

If the test light comes on for each test, and the bulb doesn't work, the bulb is bad.

 

Bulb works when switched to the left side

 

Possibly has excessive voltage drop on right side socket, (bad socket or poor ground connection). A voltmeter would be necessary to determine for sure if that's the problem.
Voltage Drop Testing

 

Thanks, will try to borrow a meter.