Thanks to our Partner, NAPA Autotech Training
Key Points & Takeaways:
The Problem:
A 2023 Jeep Grand Cherokee (collision repair) came in with blind spot warning and parking aid malfunction lights on. No functionality in either system post-repair.
Initial Diagnosis:
Verified the concern (instrument cluster lit up with warnings). Used an aftermarket scan tool (Snap-on Ultra) and found: ADAS control module had multiple DTCs for open/short circuits on all radar sensors. Parking aid module had similar codes for ultrasonic sensors. Vehicle was hit in the passenger rear, leading to replacement of the bumper, harness, and rear hatch.
Suspected Causes:
Blown fuse (common culprit for multiple system failures). Crushed/damaged wiring harness (common after collisions). Module failure due to impact.
Testing & Findings:
Checked power and ground at the ADAS module—all good. Inspected wiring harness for damage (no visible issues). Critical Clue: Wire colors didn’t match the schematic. Initially dismissed as a common schematic error. Later realized the entire harness was installed backward (left/right sides flipped).
The Fix:
Flipped the harness and radar modules to their correct positions. All codes cleared except two for the blind spot radars—turned out they were also swapped. After correction, all systems worked perfectly.
Lessons Learned:
Don’t get stuck in a diagnostic rabbit hole. Good techs pivot when clues don’t add up. Man-made problems can be the trickiest. Always verify previous work (especially after collisions). Wire color discrepancies matter. Even if schematics are often wrong, they can reveal bigger issues. "Slow down to speed up." Rushing leads to wasted time; methodical checks save hours.
Final Thoughts:
Awareness is key. Catch yourself when fixating on one theory. Experience can work against you. Stay open to new clues, even if they conflict with past patterns.
Contact Information
Email Matt:
[email protected] Diagnosing the Aftermarket A - Z YouTube Channel Subscribe & Review: Loved this episode? Leave a 5-star review on Apple Podcasts and Spotify
The Aftermarket Radio Network: https://aftermarketradionetwork.com/
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