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Ask Adam Legler Your Own Question
Adam Legler
Adam Legler,
Category: Cadillac
Satisfied Customers: 21
Experience:  Service Advisor at Antero Automotive
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Basically what's going on is my left side turn signals 't

Customer Question

Basically what's going on is my left side turn signals don't work, front or rear, right side works fine. When I use the turn signal arm in the car, I don't get any signal indicator in my instrument panel, nor clicking that happens when you have a signal on. Right side works just fine.
I bought a replacement arm thinking that was the culprit, installed, same thing. No lights or clicking when I engage left, perfectly fine on right side. I tried googling if there was a fuse but I don't think there is a separate fuse for the left and right side, could be wrong. Does anyone know if there's a separate relay or something that could be affecting just the left side? I saw someone else mention that if one of your turn signal bulbs is out, say in the driver's rear, it could also affect the driver's front. I feel like the clicking would still be present when engaged though, and possibly the light on the instrument panel.
Submitted: 1 year ago.
Category: Cadillac
Expert:  Adam Legler replied 1 year ago.

Hello, my name is ***** ***** I am a Master and Advanced Level Certified Automotive Repair Technician with over 12 years experience and I've personally worked on over 25,000 vehicles. I see you have a question about your CTS and I think I can help you.

When I read your question I had a moment of Dejavu, I'm currently looking back through my technician logs to see if I can find that fixed this as I'm sure I have been down this road before on a CTS. Give me one moment, and I'll reply back!

Again, please feel free to ask any questions that come to mind. It is my goal to determine the cause and remedy for your concern. I look forward to a speedy repair! Thank you.

Expert:  Adam Legler replied 1 year ago.

Has the vehicle been in any accidents lately? Say in the past 2 years?

Customer: replied 1 year ago.
it has been. A light t-bone. After having the car fixed the signals worked fine for about a year and it just recently started having the problem. Another mechanic suggested it may be a faulty BCM? I ordered one already, but was hoping to get some additional input before I have that programmed, in case that isn't the problem.
Expert:  Adam Legler replied 1 year ago.

I'm glad your in the loop on what it takes to do a BCM in a car these days, sometimes it can be tricky understand. Well, other than checking bulbs (first thing is first), and you've checked all the fuses already, the next step would be to do some pinpoint circuit testing. I'll warn you in advance, this is not easy, it would really help if you have an automotive test lamp with a sharp probe. If not we might be able to make due with a multi-meter.

Please let me know if you have any questions for me prior to proceeding. Since there is specific testing involved I'd like to know you're comfortable with the above steps and tools necessary for accurate diagnosis. If so I will lay out the procedures and you can report back your findings.

Simply put there are 2 wires coming out of connector X1, which plugs into your multi-function switch and travels to the BCM. The wire for the left signals is light blue and white. NOTE: there is a DARK blue and white wire as well, this is for the Right turn signals. These wires give the BCM a ground signal when the respective side is activated, telling it to start blinking, so this is what we need to test for. With a test lamp hooked up to battery positive on the clamp end, any ground touched by the probe end will illuminate the test lamp. Be careful not to stab yourself when piercing the wires. Also you probably guessed this already but this test must be done with all the connectors plugged in, as if the vehicle was operating.

Again, please feel free to ask any questions that come to mind. It is my goal to detmine the cause and remedy for your concern. I look forward to a speedy repair! Thank you.

Expert:  Adam Legler replied 1 year ago.

thanks for letting me know about the accident, it may come into play later in our diagnosis

Expert:  Adam Legler replied 1 year ago.

Attached is a picture of the X1 connector. You will be focusing on Pin 2

Customer: replied 1 year ago.
Bulbs are good because the hazards work fine. I haven't checked fuses for the BCM. I did check fuses for the lights, but the hazards work so I assume they're fine. Are there fuses for the BCM?
Expert:  Adam Legler replied 1 year ago.

just some main power fuses in the under-hood fuse-block, fuses 4 5 and 6 i believe, but nothing specific to the turn signals. Attached is a track wiring diagram of the switch and the front lamps and their involvement with the BCM.

Customer: replied 1 year ago.
Ok I will check those this afternoon. I have a friend who can perform the wire testing so I will get back to you after we figure that out. Thanks
Expert:  Adam Legler replied 1 year ago.

I'll look forward to hearing from you. Please let me know if you have any questions, I'm here to help!

Customer: replied 1 year ago.
Yeah just checked all of the BCM fuses, they all look fine, so I will rule that out. Has to be a wiring issue between the turn signal switch and the BCM, or the BCM itself.
Expert:  Adam Legler replied 1 year ago.

Agreed, let me know your results when you have them, I'll cross my fingers for ya! Thanks again for allowing me to help with your concern.

Expert:  Adam Legler replied 1 year ago.

Hello again John. Did you get your BCM replaced in the Cadillac? Just wanted to check in and make see if there was any additional assistance i can be.

My goal is to provide you with excellent service – if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are ready!

Customer: replied 1 year ago.
I'll be doing the electrical testing Tuesday so I'll have more info then. Thanks
Expert:  Adam Legler replied 1 year ago.
Great, just let me know. Thanks again!
Expert:  Adam Legler replied 1 year ago.

Good morning John, just following up, did you have a chance to work on the Cadillac yesterday? I want to apologize in advance if I seem persistent, the premise behind this system of Q&A is for timely responses and customer satisfaction. Since I am invested in your concern, I'd like to follow it through to the end if it will be in a timely manor. Thanks again!

Customer: replied 1 year ago.
No apology needed. My friend wasn't able to yesterday. We will try to get to it early next week. I'll keep you posted.
Expert:  Adam Legler replied 1 year ago.

Sound fine, I'll look forward to hearing from you next week then. Thanks again