New to chevy and this site. Help with Turn Signals & Flashers

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78-3/4ton

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I have no functional turn signals but have headlights tails and markers.... can anyone tell me what this is and what it goes to? I done see a matching plug under the dash
 

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74propu

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cruse control out of the column
 

1987 GMC Jimmy

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Yep. It plugs in under the dash near a fat vacuum line. Actually, let me embed a video. These videos don't show it the best, but maybe you can deduce where it goes if you watch carefully. Oh, and plugging that in may restore your cruise, but it won't do anything for the lack of turn signals. Do you have hazards? You may just need a new turn signal flasher relay. It's located in the fuse block.

[yt]4fKxDon-9Yw[/yt]
 

78-3/4ton

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Ok thanks.I don't have cruise on this truck so I'll just tuck it away.
 

78-3/4ton

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Nope no flashers either... I guess that relay would be the cheapest fix...
 

Old77

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:welcome: to the site
 

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It must have come with it, and the PO deleted the hardware. Try replacing those flashers. It's a '78 so they should be in opposing top and bottom corners of the fuse block.
 

78-3/4ton

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This is what I've got
 

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This is what I've got

Ahh, okay. You've got the old glass fuses. The red one is gonna be your hazard relay and the round one should be the turn signals. However, I've never seen a square flasher. It should be just a little cone shaped relay with two pins that form a right angle just like the turn signal flasher you have. I'd try replacing those and the hazard flasher with the correct relay.
 
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HotRodPC

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Welcome to GMSB !!! This is obviously going to turn into a Turn Signal and Flashers troubleshooting thread, so it's been moved to the Electrical Section and Title changed to get better attention for the help you need. :waytogo:

My first suggestions have already been mentioned in checking the flasher relays. I'm doubtful that's the problem though since it's not likely BOTH flasher relays would go at the same exact time. The turn signal switch itself does control both the flasher and turn signals so it is possible after checking the basics FIRST, you're going to end up pulling the steering wheel to get to the turn signal switch.


But don't be discouraged that it's not the relays. It's very possible the flashers relay went long ago and you weren't aware of it since you don't use them very often. Then the turn signal relay went so now you've noticed.
 

78-3/4ton

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I appreciate it all... I just got this truck and it needs work just trying to get her road worthy first
 

chengny

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Not mentioned is whether the brake lights are working - that is important because the rear directionals and brake lights share a common filament.

The first check (for me anyway) would be that the correct lamp is installed in every associated socket. The correct bulb for the front (TS & PRK) and rear (TS/BRK & PRK) is an 1157 - two pin type. People often jam a single pin bulb into a two pin socket.

Also since you have AGC type fuses, you would be wise to check them for continuity with a meter and not rely on the condition of the visible part of the element. In some instances (cheap AGU fuses, in particular), the fusible element will become desoldered from the end cap - and still appear to be intact, yet the fuse will stop or only intermittently pass current.
 

78-3/4ton

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Break lights do work properly... fuses pass current via multimeter testing
 

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