Pre-Trip Help: Clearance Lights Or Marker Lights?

Hello all,

On Monday I have my CDL test. I've done my 160 hours.

I feel confident that I will pass the pre trip portion but I never quite got it cleared up what these lights are called. I want to make sure I'll use the right terms.

First image is of a red Cascadia. The light right in front of the door. Is that a marker light or clearance light?

Second is a picture of a great dane trailer. At the back corner is that a marker light or clearance light?

Any other tips or advice is appreciated!

This has always confused me. If you google “difference between marker lights and clearance lights on a semi truck”, you will get a lot of info including some pre-trip light related videos.

Marker lights.

Clearance lights are up above.

From what I understand, both your pictures are marker lights, but somebody more knowledgeable than me might be able to give a more definitive answer. I thought the Junior Honduras YouTube video about lights and reflector tape was good.

Many times these terms are used interchangeably. Although it’s incorrect, some officials administering the CDL pretrip test might ding a student in misusing these terms. Or maybe not.

To be sure… By definition clearance lights identify the extreme width and height of a truckcab, truck body and trailer. Like the upper corners of a trailer and tractor cab. Above the trailer doors, etc. Obviously there are tolerances here… some tractors have the 5 clearance lights on the cab roof. Others are above the windshield (Cascadia as an example).

Rule of thumb… Anything up high is a clearance light. Anything lower are marker lights. I think the important takeaway is, if it’s a light and not a reflector, it’s needs to illuminate. If it doesn’t illuminate, get it fixed.

"Needs to illuminate."

I'll add that to my wording. We've been saying "And works properly."

To be safe I will say both. Thanks G-Town.

Many times these terms are used interchangeably. Although it’s incorrect, some officials administering the CDL pretrip test might ding a student in misusing these terms. Or maybe not.

To be sure… By definition clearance lights identify the extreme width and height of a truckcab, truck body and trailer. Like the upper corners of a trailer and tractor cab. Above the trailer doors, etc. Obviously there are tolerances here… some tractors have the 5 clearance lights on the cab roof. Others are above the windshield (Cascadia as an example).

Rule of thumb… Anything up high is a clearance light. Anything lower are marker lights. I think the important takeaway is, if it’s a light and not a reflector, it’s needs to illuminate. If it doesn’t illuminate, get it fixed.

I'll add that to my wording. We've been saying "And works properly."

Say what you're used to saying. It works, it's not cracked or broken and it's the appropriate color. That's what they're looking for.

Don't disrupt the rhythm this close to game day.

Banks wrote:

Say what you're used to saying. It works, it's not cracked or broken and it's the appropriate color. That's what they're looking for.

I agree. Good advice.

Agree not to change up your script.

Prime in Springfield gave us a 10-page script to memorize for the pre-trip exam to pass the MO CDL exam requirements. The script worked if followed exactly.

I thought G-Town’s comment about lights needing to be illuminated or to get repaired was pertaining to doing an actual pre or post trip inspection in real life. Not for passing the CDL exam.

I agree with the gentleman above. "Works properly" is good enough, don't go making it harder than it needs to be by adding extra words.

Keep it short and to the point.