TROUBLESHOOTING TRAILER LIGHTING
Replace
Fuse(s)
Fix
Connection(s)
Fix
Connection to
Vehicle Wiring
© 2006 - 2007 Thule Towing Systems, Llc
Using a Test Light
Check Left Turn, Right
Turn, Brake Light and
Tail Light Functions
All Outputs
Functional With
Same Intensity?
No
Check
Fuse(s)
Fuse(s)
No
OK?
Yes
Check
Converter
12v+ & Ground
Connection(s)
Connection(s)
No
Good?
Yes
Using a Test Light,
Check Converter Input
Wires for Signal
Input Signal(s)
No
OK?
Yes
Check for 4-Flat
Connector Damage
4-Flat OK?
Yes
Replace
Converter
Converter
Yes
Installation OK
Connect
Trailer
Trailer
Lighting Functions
Reversed?
No
All Trailer
Functions
Operational?
Yes
Ready to Tow
TESTING METHOD
1. Attach the test light ground connection
to the male pin of the converter's 4-flat
connector.
2. Probe each of the female pins individually
to confirm correct circuit operation.
Right Turn/Stop Green
Left Turn/Stop Yellow
Tail Lights
Ground (-)
Yes
Check Trailer
Connector for
Function
Compatibility with
Vehicle Connector
No
Converter Has
Automatic
Shutdown
Capability when
Overload or Short
Circuit Conditions
are Present in
Trailer. Repair
Trailer or Remove
Some of the Lamps
in the Circuit
Brown
White
Rev B 11/30/07
52260-998