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Turn Signal problem, left signal=all flash


SM 2003
Full Member
Aug 10, 2003
NW Indiana (Chicago Area)
I have searched and couldn't find a similar problem.

I figured before I try to troubleshoot I would check in for anybody with experience with this issue.

I have done no lighting mods except for ambers.

When I activate the left signal all the lights flash like the hazards are on, the right turn signal works normal. This happened a month ago as well but went away after few minutes.

2003 Z66

Any help is appreciated and if no one has seen this then I will be the first.

I have had the same problem it only gets worse! I called GM and they told m it is the flasher module  That curiously has been recalled on Trail Blazers and Tahoe's but not the Avalanches. I've posted a question as to its location  Can't seem to find where it is :)
The module is usually under the dash, not sure where I would turn on the side that works and follow the clicking sound to find it . I'd look at mine but I'm at work and this raining

Only info I found is below

The IGN E 10 A fuse in the underhood fuse block supplies battery positive voltage to the turn signal/hazard switch assembly. The FLASH 25 A fuse in the I/P fuse block supplies battery positive voltage to the turn signal/flasher module and ground is supplied at G200. When the turn signal switch is placed in either the left or right position, a voltage signal is completed from the turn signal switch to the turn sign/flasher module. When the hazard flasher switch is activated, a ground signal is completed from the turn signal/hazard switch to the turn sign/flasher module. The turn sign/flasher module then sends an on-off voltage signal through the LT TRLR, RT TRLR, LT TURN or RT TURN 10 A fuses in the I/P fuse block to the appropriate turn signal or to all 4 fuses for hazard operation. The instrument panel cluster (IPC) indicators receive voltage from the LT TURN and RT TURN fuses as well as the DDM/PDM for the mirror turn signals. The DDM/PDM has no function or control of the mirror turn signals other that a pass through connection for the circuits. The audio chime is also activated when the turn signals are on. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators. The front turn signals are grounded at G100. The rear turn signals are grounded at G401. The Mirror turn signals are grounded by the DDM/PDM.