2003 ranger turn signal inop

[mikmaster63]

left rear turn and brake are not working. replaced turn signal switch and plug. flasher is clicking fast and the front one works. any ideas?

 

[bmerr98]

Maybe bulbs? Check power to the bulb sockets with a test light and go from there. IMO the bulbs are the weakest link and most susceptible to failure.

 

[mikmaster63]

oh ya checked bulbs. I'm a master rv technician so all the obvious stuff has been ck'd. I have traced down all the harness down the frame and most of the wiring under dash. I heard there is another module on fords that controls stop and turns???

 

[adsm08]

Nope. Straight-forward simple circuit. Turn and Stop use the same filament on a 2-filament bulb. There is only one ground for the bulb.

 

[mikmaster63]

so it's safe to assume that the ground is good at the taillight since the running lights work. I tried a known good ground and tested the lt grn/org wire and there is no power there. I traced the harness to a plug under the vehicle, unplugged it and found left and right turn power there. only on the harness side of the plug there is no corresponding wire for left turn (it's just blank). is it safe to assume this truck has never had a left turn?

 

[adsm08]

Well I have seen dumber things happen than a misbuilt harness, but I also find it hard to believe that this truck has been running around for 10 years without a left rear turn signal or brake light.

 

[freedom5]

I've had that happen many times over the years and always found it to be the brake/turn side of the bulb being out. Being a " Master RV Technician" I know you have tried another bulb. The reason the indicator flashes rapidly is because there isn't enongh load on the flasher. You can disconnect the plug and take a volt meter with a probe to see if there is voltage to both pins when the parking/headlights and turn signal is on.

 

[RonD]

Reads like someone added trailer lights and F-ed up when removing them.
If you have turn signal power on the forward harness(to the cab) then I would just run a new wire from there to the bulb socket