Left turn signal comes on when I hit brakes

GULLWING004

MEMBER
2003 CADILLAC ESCALADE EXT
200,000 MILES

When I hit the brakes intermittently the left turn signal will come on steady, also if using left turn signal it will sometimes turn steady when brakes are applied. The bulbs are good. Where are the grounds for this system? Other possible causes? Also, on occasion when using cruise, hitting the left turn signal will shut the cruise off.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Hello,

This sounds like a problem with the BCM I would have the unit scanned to see what come up.

Here is the location and wiring diagrams for the BCM and the turn signals so you can check the grounds:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-use-a-voltmeter

and

https://www.2carpros.com/articles/how-to-check-wiring

If it does look like the BCM after testing you will need shop to program it for you.

Please let us know what happens.

Cheers, Ken

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Friday, November 3rd, 2017 AT 2:40 PM

GULLWING004

MEMBER
8 POSTS

Bcm tested ok, have replaced the left tail light harness, the turn signal switch, added another ground to the system, brake pedal switch next

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Tuesday, November 7th, 2017 AT 10:12 AM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Looking at the blinker wiring diagram it looks like the flasher module could be causing the issue as well. Here is its location (below)

I would check the rear junction block for damage moisture.

"Rear Lamps Junction Block On rear inner side of right frame rail."

Please let us know what happens.

Cheers, Ken

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