Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

1. Probe the marker lamp circuit at the connector that it is inoperative from upfitter connector or tractor trailer receptacle, with a test lamp that is connected to ground.
2. Place the marker lamp switch in the ON position.

Does the test lamp illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

Do the vehicles marker lamps operate properly?

Go to Step 4

Go to Marker Lamps Inoperative

Repair an open or short to ground in the marker lamp voltage supply circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 5

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3