§393.20 specifies where clearance lamps must be mounted on the vehicle: on the permanent structure of the vehicle, such that they indicate the extreme width and (where required) the extreme height. The specific lamp count, color, and placement come from §393.11 read together with the Subpart B mounting requirements; §393.20 governs the where, not the whether.
Severity weight
Severity weight 1 in the Vehicle Maintenance BASIC. The finding is most often paired with §393.9 (inoperative required lamps) and §393.11 (missing reflectors), so the citation rarely lands alone.
How it gets cited
The two common patterns: (1) clearance lamps installed but on a temporary mount (a load bar, a tarp frame, a strap-on light bar) rather than the permanent structure; (2) clearance lamps physically present but mounted in a way that does not indicate the extreme width — typically because a body modification moved the widest point but the lamps stayed where the OEM put them.
How to prevent it
- After any body modification (sliding tandem, side rail addition, replacement bumper), verify the lamp positions still indicate the extreme width.
- Verify clearance lamps are bolted to the permanent structure during the §396.17 annual inspection.
- Pre-trip lamp checks should include a quick visual confirmation that the side marker and clearance lamps line up with the vehicle corners, not the trailer-half corners.
How Roadworthy HQ helps
Vehicle Maintenance findings link to the vehicle record, attach to the corrective-action note from the §396.9(d)(3) repair certification, and surface on the audit binder so the §393.20 finding and its remediation are documented together.