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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29430
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Turn signals/4 ways quit working. 2004 GMC 3/4 ton. Replaced

Customer Question

turn signals/4 ways quit working. 2004 GMC 3/4 ton. Replaced the turn signal module, It worked for a little while, but turn signals flashed really fast. 4 ways worked normally. Worked for about 1 week and then quit. No bulbs burnt out.
JA: Have you checked the fuse?
Customer: So far as I can tell, all fuses are good.
JA: What is the model of your '04 GMC?
Customer: Sierra
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: Pulled the signal/4 way module out, plugged it back in. I have a feeling it is something else though.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Not at this time.
Submitted: 5 months ago.
Category: GM
Expert:  GM Tech (Cam) replied 5 months ago.

Hi there, I am Cam.

With your flasher module, what brand did you install?
Was it new or used?

Customer: replied 5 months ago.
The brand was a "Standard". Did not go OEM for this part
Customer: replied 5 months ago.
I do not know how the circuit works, but it would be helpful to know what all the connections are for which the module plugs into. Also, before the original flasher failed, it flashing fast to the left, but all bulbs were working.
Expert:  GM Tech (Cam) replied 5 months ago.

Its basically a couple small relays inside that split the circuits up for truck and trailer.
The fast flashing was possibly a failed relay. This one though, it should still light them up. Let me get you a schematic.

Customer: replied 5 months ago.
If the fault is in the new relay that I put in, I will return it for another. It is quite uncommon to get faulty new parts though. When I move the signal lite lever, I can hear a click coming from the module, but only one click.
Expert:  GM Tech (Cam) replied 5 months ago.

OK, do the brake lights work and I didn't ask you about the hazard lights?

Customer: replied 5 months ago.
The brake lights do work. The hazards do not work.
Expert:  GM Tech (Cam) replied 5 months ago.

If the FLASH fuse gets power with the key on then I am really thinking you have a problem with the flasher and replacement should be considered especially if you have warranty.

Expert:  GM Tech (Cam) replied 5 months ago.

here is the schematic.

Customer: replied 5 months ago.
I will give it a try after the weekend. I will let you know how it works out
Expert:  GM Tech (Cam) replied 5 months ago.

Thanks.