An SUV’s turn signal is constantly on the blink

How To

John Paul, AAA Northeast’s Car Doctor, answers a question from a reader dealing with a recurring turn signal issue.

By John Paul

September 23, 2025

3 minutes to read

Q. I have a 2025 Cadillac Lyriq with 2,500 miles and a chronic problem with the left turn signal. The signal will intermittently fail. I got an error message to check the taillight bulb. I’ve had the car to the dealer twice. The first time they rebooted the software with no success. They then replaced the taillight assembly, and this corrected the problem for about a month. The second time the taillight failed I brought the car in for service and the service manager saw the taillight was not working. However, when they restarted the car to bring it into the service bay the taillight was working fine. GM stated that this is not a known issue, and there are no recalls. If I turn the car off and let it sit for a while the problem does resolve itself. This is becoming a major concern and annoyance.

A. Since replacing the taillamp assembly fixed the issue for a while, it seems like it could be related to a wiring problem. I did see one technical service bulletin that mentioned a harness retainer clip that could allow the wiring to rub on an axle. As a side note, the all-electric Lyriq has a long list of technical service bulletins (and I don’t see them all) and many are software related. At this point I would try to document the failure as much as possible and see if the dealer can get a Cadillac field engineer out to investigate the issue. 

Q. I know you are a safety guy, and I believe you got an award from NHTSA for your efforts. What are your thoughts about electric scooters? I see people buzzing around on them all the time. My college student, who can’t have a car yet, wants one to use in and around her campus. 

A. E-Scooters are considered micromobility devices and certainly have their place. Recently I have been riding a Kaabo Urban e-scooter, and although I have ridden both electric and manual bikes, gas scooters, and motorcycles, at first I found the e-scooter a little terrifying. Now that I have practiced a bit, it is a fun way to get around. The Kaabo scooter is well made, has decent performance, and very good brakes and suspension. Required or not, I would recommend a helmet and other safety gear. I would also not modify the speed – 15 miles per hour is plenty fast. And like all vehicles, never ride impaired or distracted. 

Q. Walmart has full synthetic and advanced full synthetic motor oil. The advanced is 66 more cents. Is it worth it?

A. The Walmart Advance synthetic oil looks like it is designed for extended oil changes. The difference between the SuperTech Synthetic and Advanced Synthetic oil is likely the additive package, which may allow longer intervals between oil changes. Although any advanced synthetic oil may offer better protection against wear, I do not believe in extended oil changes unless the oil is analyzed on a regular basis. You could certainly use this advanced synthetic oil but replace the oil and filter at the manufacturer’s recommended interval. 

Q. While doing other repairs on my 2005 Jeep Grand Cherokee, my mechanic noticed a minor leak from the transfer case. First, he said he added some ‘stop leak’ fluid to the unit. At pick up he said he “temporarily disconnected the 4-wheel drive” until we replace or rebuild the unit. It is not leaking and drives fine for now. It has been only in my family, is always well maintained, and has been well-kept since brand new. I know it is old, but my adult son exclusively drives it and can’t afford to buy another vehicle now.

A. If the fluid level is full and not leaking, I would hook up whatever your mechanic disconnected. The shop may have removed a fuse or even the front driveshaft. The sealer may have swelled the seals and stopped the leaks. Certainly a stop gap repair, but at 20 years old it may be a good enough solution. 

Q. My 2009 VW Jetta SportWagen remote recently stopped beeping when I lock my doors. The battery is new. I like the idea of hearing this sound to confirm the doors are locked. Is there a way to retrieve the beeping sound when locking? I don’t have the car owner’s manual, and the dealer was not much help. 

A. The first thing to do is make sure the horn works. Then, if there is a menu, look for ATA settings. This is the notifications which chirp or flash. Some VWs have this menu, others do not.  Here is a link to an owner’s manual. The manual is over 400 pages. Go to page 235. It explains resynchronizing the remote and finding the settings. 

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.