My left turn signal no longer works on my '00 T&C. Hazards, brakes and right turn signal works. I've replaced both lights in front and back, replace turn signal switch and check fuses'. What else can I do. Also, when I replaced the turn signal switch, i noticed that a wire was not plugged into the back of the steering wheel. Not knowing what it is I am not willing to plug it back in. I do have pictures, but no idea how to post them. Any ideas are grateful.

Any ideas on what else to check?
Yeah, hook up a professional grade scan tool an check for DTC'S -diagnostic trouble codes in the BCM - body control module. Seeing how it controls (turns on) these lights. Turn/hazard indicators flashing fast means a bad bulb or short circuit somewhere.

DTC B3949: Right Front Turn Signal Circuit
Circuit/System Description
Ground is applied at all times at G200 to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through their respective control circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed ON and OFF.

DTC B3951: Right Rear Turn Signal Circuit
DTC B3951 will set when the BCM detects a short to ground or an open/high resistance in the RR turn signal control circuit.

DTC B3950: Left Rear Turn Signal Circuit

DTC B3948: Left Front Turn Signal Circuit

DTC B3445: Stop Lamp Circuit

Brake lights /rear hazard lights not working - Ford Truck ...

www.ford-trucks.com > ... > 1967 - 1972 F-100 & Larger F-Series Trucks
Jul 9, 2010 - After checking the brake lights I tried the emergency flashers and found that they are working in the front but not in the back. I do have rear turn ... 1995 F350 Brake Lights / Turn Signals not working
Jul 9, 2012
Turn Signals and Brake Lights Do Not Work
Mar 10, 2012
Turn Signal, Brake Lights, & Rear Hazard not working
Aug 3, 2010
Rear Turn Signals, Hazards and Brake Lights not working....
Aug 29, 200

it all points to a fault with a common ground. Find earthing points

The signal wire going to the right front has a splice for the dash indicator, a wire branching off from the turn wire and going to the dash. It sounds like that right signal wire is broken or lost a connection before it splices off to the dash, so the problem sounds like it is under the dash, either coming out of the turn signal switch to the flasher or from the flasher to that splice. You may need a multi-meter to check voltages on that wire at various places under the dash. Ascertain which color wire you need to concentrate on. Check for voltage on it with key on and right blinker on-voltmeter will spike to battery voltage, then fall to zero as the flasher breaks voltage continuously, if checked after the flasher. If checked when leaving the turn switch, it should be a continuous signal on that wire. Think you better find a wiring diagram to find the right wire to check. Good luck.

I don't believe it would be a bad ground for just one light. It could be a wire, a socket connector, or the bulb socket itself. See if the wire has power at the socket when signaling left, with key on. If there is power, probably a bad socket or connector. If no power, check for power coming from flasher-the wire going to front left, or driver's side. If you have power from the flasher, but nothing at the socket, the wire has probably broken.
Good luck.

On a "one brake light bulb per side" setup,the brake switch feeds 12v to the turn/hazard switch,and the switch will apply 12v to both when no turn signal activated,the right only when the left signal is on,the left only when the right signal is on,and none when the hazards are on.With this in mind,it IS possible that the turn signal switch or wiring is the issue.If you are still running the original switch,try removing the switch and cleaning/regreasing the contacts(or look for something obviously worn or broken).If the switch is bad-hey,you got almost 50 years out of it! I'll bet you won't get that much longevity out of anything built now!
'

IF THE TURN SIGNALS STILL WORK IN THE FRONT, THAT MEANS THE FUSE & THE FLASHER ARE OK. IF THE SIGNALS DON'T WORK AT ALL CHECK TURN SIGNAL FUSE & STOP / BRAKE FUSE. ARE YOU SURE THE CORRECT BULBS ARE BEING USED?

Have you tried replacing the bulbs? The two side lights run through the turn signal switch so if they aren't getting power, chances are your signal switch is bad. Do your front blinkers work? Do the rear lights come on when you use the blinkers or the hazards?

I had this problem, and to be honest, it happened to the left side about a week later...it's the board that the bulbs plug into...it's a very common problem with this model. So popular that you can normally get the socket board off the shelf at a parts store! it's extremely simple to replace, and I replaced all the bulbs at the same time!

it sounds like your flasher is going out and if not that then it could be a short in the system