Troubleshooting Trailer Disconnected Alert Alarm on 2018 Toyota Tundra

Published 10/23/2018

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Dielectric Grease for Electrical Connectors, 2 oz.

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Digital Multimeter with 42" Long Test Leads - LED Display

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Hook Probe Circuit Tester

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Question:

My 2018 Toyota Tundra gives me a trailer disconnected alarm when I hook up my Airstream travel trailer with LED bulbs. The dealership tested the truck and trailer and said the trailer was only showing .1 ohm resistance thats why I was getting the alarm. So I ordered and received item #20142 after I saw that it would solve the problem. I hooked the trailer up today and same problem trailer disconnected alarm. Could the part be bad?

asked by: Harvey L

Helpful Expert Reply:

There is an adapter to help with LED trailer lights that has the load resistors you are seeking. It is the Trailer Connector Adapter w/ Lamp-Out Sensor Bypass - 7-Way RV to 7-Way RV - Vehicle End # 20142.

The issue when trailer disconnected alarm or alert comes on is normally specific to your electric brake controller output pin which is normally what senses a slight draw and communicates that the trailer is connected. The 5 o'clock pin on your 7-way is the brake controller output and you may simply need to clean that connector on both the truck and trailer side with some sand paper so you have a better connection. Then use some dielectric grease # 11755 to keep moisture and debris out of that connector.

expert reply by: Jason S

click to enlarge

Harvey L.

10/12/2018

There is an adapter to help with LED trailer lights that has the load resistors you are seeking. It is the Trailer Connector Adapter w/ Lamp-Out Sensor Bypass - 7-Way RV to 7-Way RV - Vehicle End # 20142. The issue when trailer disconnected alarm or alert comes on is normally specific to your electric brake controller output pin which is normally what senses a slight draw and communicates that the trailer is connected. The 5 o'clock pin on your 7-way is the brake controller output and you may simply need to clean that connector on both the truck and trailer side with some sand paper so you have a better connection. Then use some dielectric grease # 11755 to keep moisture and debris out of that connector.

Jason S.

10/12/2018

If the dealer is saying that is the is low power draw on the 2010 Airstream LED lights, then the load resistors in the Trailer Connector Adapter w/ Lamp-Out Sensor Bypass # 20142 will solve that issue. The load resistors will require the draw of incandescent bulbs so you will have the correct draw at that adapter to allow your truck computer to recognize the functions correctly and that alarm will not be triggered.

Harvey L.

10/23/2018

Jason S.

10/23/2018

I'm sorry this process must be so frustrating. I wish I could do some testing for you, so we could solve it more easily, but we will continue to do troubleshooting until all options are exhausted. The Trailer Connector Adapter w/ Lamp-Out Sensor Bypass - 7-Way RV to 7-Way RV - Vehicle End # 20142 can be bad as no manufacturer is perfect, but it isn't very likely. I recommend installing the adapter on your vehicle and then checking the voltage at each pin when you activate the functions using a circuit tester like # PTW2993 or a multimeter like # BTMT15 on the 20v setting using the red probe on the pin you are testing and the black probe on a bare metal ground to the frame. I've attached an article and photo to assist. If the lighting sensor goes out when under the draw of the tester, then we know the adapter isn't drawing enough load and should be replaced if not working or added to with more load resistors if more draw is needed (which I haven't experienced before). The Putco LED Light Bulb Load-Resistors - Aluminum - Qty 2 # P230004A-2 are what can be used if the adapter isn't working or isn't drawing enough load for the sensor. These are added to each powered feature of your trailer to increase the draw, so you would put one on each turn/stop wire and one on the running light and one on the reverse light. The electric brakes, 12v power, and ground wires won't need them. I've attached the correct installation photo to help if you choose to go this route if the adapter is working and yet either isn't enough draw or isn't working and you wish to go this other route.