Cadillac XT4 Won't Start After Wiring Harness Repair

Recently dealt with a similar situation on a 2017 Cadillac XT5. The symptoms match exactly, no start condition after wiring harness work near the battery terminal. The issue turned out to be a poorly reconnected ground cable affecting the starter solenoid signals. The car would not start consistently and threw multiple error codes because the main power distribution was compromised. The fix required tracing the entire circuit from the battery terminal through the wiring harness to the fuse box and starter. This is typically a serious issue requiring immediate attention since intermittent power delivery can damage expensive electronic components. When the car won't start due to wiring problems, it often indicates either loose connections or pinched wires from previous work. The repair involved: Complete inspection of battery terminal connections, Testing starter solenoid function, Checking all ground points, Verifying fuse box connections, Re-securing wiring harness routing Recommend having a qualified technician inspect all recent work areas, particularly focusing on ground connections and wire routing near recent repairs. Poor connections in the power distribution system can cause cascading electronic issues.

Thanks for sharing your experience with the XT5. What you described sounds very close to my situation. The relay switch certainly seems like the prime suspect here. My car keeps switching between completely dead and showing multiple unusual warning lights. I am planning to take it back to a different garage this time, as I want a fresh set of eyes looking at the ignition switch and circuit break connections. Since you had success fixing a similar issue, would you mind sharing what the repair cost you? Also curious if you have had any other electrical gremlins pop up since the fix?

Good news, got the issue fully resolved on my XT5. The primary problem was indeed with Terminal 15 ignition positive being interrupted, which we discovered was causing those unusual electrical issues you mentioned. After getting it properly diagnosed, the repair focused on fixing a faulty cable connection near the ignition switch. The total bill came to 95€ for parts and labor, which included testing the voltage drop across various circuits to pinpoint the exact problem. Since having the connection restored at the fuse box, the car has been running perfectly with no electrical issues whatsoever, no more warning lights or starting problems. Given your similar symptoms, I would definitely have them check the circuit break and starter solenoid connections near where the previous work was done. A proper voltage test should quickly reveal if you have the same interrupted power supply issue I experienced.

Thanks everyone for the helpful replies. Just wanted to update on how things turned out with my XT4. I took it to a different garage as planned and they found the exact issue, a pinched wire in the main power supply harness that was causing intermittent voltage drops. The mechanic showed me where the previous work had caused the wire insulation to get damaged when the harness was being reinstalled. They had to replace a small section of the wiring and properly secure the harness. The repair took about 2 hours and cost 180€ total. Since the fix last week, my car has been starting perfectly and all those unusual error codes are gone. The fuse box connections were also cleaned and tightened as a precaution. Really glad I got a second opinion instead of going back to the original shop that caused the problem. Just shows how important proper wiring work is, one pinched wire near the relay switch caused so many confusing symptoms. At least it is sorted now and running like new again.