TIROL 13 Pin Towing Trailer Car Caravan Tow Bar Light Circuit Tester Unit for Plug Socket connection 12 N T23331b

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Product Details & Item specifics

Item Type: Diagnostic Tools

Item Name: Trailer Tester

Place of Origin: Ningbo China (Mainland)

Brand Name: Tirol

Item NO.: T23331

Size: 20.5*4.5*5.5cm

Weight: 220g

Material: ABS+ copper

Certification: CE, ROHS, PAHS

Color: Black

Features: Trailer Tester for 13 pin plug and socket connection

Product Description

Tester for 13-pins plug and socket connection

This tester has one side to connect the 13-pins plug of a trailer and another side to connect the 13-pins socket of a car. This tester indicates quickly if a failure concerns the wiring of the car or the wiring of the trailer. How to test the connection of a:

Car, camper

  1. Put the tester in the socket of the car.
  2. Press the yellow button on the side of the tester.
  3. If the wiring is good, all the LEDs light up. Do again steps 4 as previous.

You can also test the functions of each pin of the socket.

1. Switch on the left hand indicator (after switching on the ignation key).

2. The corresponding LED must flash with the same frequency. If not, left hand indicator wiring is defective/broken.

3. Repeat steps 1 and 2 for the right hand indicator, rearlight, foglight and stoplights.

With a +/- 4 m extension cable, you can test the functions form the driver’s seat more easily.

See below the table for the potential problems:




Car( by pressing yellow button)


Some LEDs do not light up

Wire damaged or bulb defective. Bad contact

See Left


None of the LEDs light up

Mass wire damaged or all bulbs defective. Check the battery of the tester.

See Left


One or more LEDs are weak or twinkle

Wire damaged or contacts dirty in the plug.

Wire damaged or contacts dirty in the socket


All the LEDs are weak or twinkle

Mass wire damaged. Check the battery of the tester.

See Left


The lights of the trailer do not light up t the LEDs do

Short circuit in the trailer wiring. The fuses will break.


NB If the vehicule is equipped with an electrical foglight interruption relay. This one has to be tested with a 21 wattbulb.

Testing the socket

Connect the tester to the vehicle power socket. If the vehicle is fitted with a 7-pin socket, a 7-to 13-pin adapter (not supplied) must be plugged in between.

Switch on the ignition and test all functions with the aid of a 2nd person. With proper assignment of the socket the corresponding indicator lights up (when testing the direction indicator, the light will also blink).

Testing the plug

Insert a 9V battery (not included) into the tester’s battery compartment into the right direction. Connect the tester to the trailer plug (of course also suitable for lighting bars, bike carriers, boat trailers etc). With a 7-pole connector an adapter from 7-to 13-pin (not included) must be placed between the vehicle and the socket.

Press the test button on the side. If the trailer is equipped with all function (indicator, braking light and rear fog light), the corresponding indicators must light up when the test button is pressed. Please note that not all trailers/ trailer boards/bike carriers have a rear and/or a reversing light. In that case, the corresponding indicator does not light up. Use this function only when testing a plug!


If during the test no indication will light the ground line usually is interrupted. Check whether the 9V battery (not included) is fully charged. Or replace the battery. If individual indicators don’t light up check their bulbs and the cables leading to them. Clean plugs/sockets and check that the contact screws in the plug/socket are securely fastened. And make sure the wiring is connected according to the wiring diagram 7-or 13-pole.

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