2004 GMC Envoy turn signal problem

Replace bulb 1st 'Check wiring harness and socket

I have replace bulb. How do I check the wiring harness and socket

1st need to verify fuse #43 below left rear back seat has battery power. With signal on if not check TAN wire back at the flasher module if yes check Dark Blue wire at the socket NO power. Trace the wire harness and repair the short.

Fuse #43 is good. So I check for power on the DK BLU wire at the socket and there is no power. I have no diagram to trac the wire harness. Any suggestion.

this may help

Thanks for the drawing. It turn out that the front socket bad. Need GMC or replacement part number for socket. Again thank you.

2004 GMC ENVOY 4.2L 256cid L6 FI (S) DOHC :
Electrical-Lamp & Socket : Turn Signal Lamp Socket

ACDELCO Part # LS259 {#88862199} 3-WAY FEMALE
SOCKET,FRT SI MKR LP 4 WHEEL DRIVE; OE 12083689, 3 WIRES
SOCKET,FRT SI MKR LP 2 WHEEL DRIVE; OE 12083689, 3 WIRE


ACDELCO Part # LS260 {#88862200} 3-WAY
SOCKET,FRT T/SIG LP 2 WHEEL DRIVE; OE 12083680, PARK AND TURN SIGNAL LIGHT
SOCKET,FRT T/SIG LP 4 WHEEL DRIVE; OE 12083680, PARK AND TURN SIGNAL LIGHT

I replaced the socket and still have the same problem. I checked across the contacts the blue wire go to on the bad one and had an open. When I got the new one I checked across the same contacts and had a short. When I installed the new the blub it was still blinking fast so I remove the bulb and checked across the contacts and now I have an open. What is going on.