How to Test a 7-Pin Trailer Plug with a Multimeter (4 Steps)
Content
In this guide, I will teach you how to test a 7-pin trailer plug with a multimeter.
As a professional handyman, I often test 7-pin trailer plugs with a digital multimeter without any problems. The 7-pin trailer plug is tricky because it contains 7 connectors in one place. But still, with the right guidance, you can easily test it at home to see if there's an electrical break in the plug, and even fix a 7-pin trailer plug instead of buying a new one.
In general, testing a 7-pin trailer plug with a multimeter takes only a few minutes:
- Get the right tools and supplies
- Understand the 7-pin trailer fork configuration
- Prepare your multimeter
- Connect the multimeter leads to the lower left and upper right connectors of the 7-pin end plug.
- Check each bulb to see if any of its wiring is faulty.
- Check the turn signals, brake lights and reversing lights.
I'll tell you more below.
Tools and materials
For proper testing, the following things are needed:
- 7-pin trailer connector
- Multimeter with black / red probes - for checking voltage.
- Two people: one to drive the car and one to operate the multimeter
- Replaceable bulbs (optional)
- Sandpaper (optional)
- Electrical contact cleaner (optional)
7-pin trailer plug configuration
The 7 pin trailer plug is a challenge as it contains 7 connectors in one place.
Other types of plugs may be available with 3, 4, 5, or 6 different connectors, but in this article, I will focus on the most typical 7-pin plug.
The fork is almost always set up the same, but if you're not sure, you can go back to the original manual you received when you bought it. For a standard 7-pin connector, the following configuration will be used:
- Top right - 12 volt hot wire
- Middle right - right turn or brake light
- Bottom right - brake controller output
- Bottom left - earth
- Middle left - left turn or brake light
- Top left - tail and running lights
- Center - reversing lights
Checking a 7-pin plug with a multimeter - procedure
Use your DMM (and make sure it can test voltage) to see if any of the wiring in the 7-pin plug is faulty.
Step 1: Prepare your multimeter
The arrow of the multimeter should be turned towards the V symbol. Then connect the red wire to the voltage port and the black wire to the Y COM port.
Step 2: Connect the multimeter leads to the lower left and upper right slots.
The black test lead, the ground wire, must be inserted into the bottom left socket of the 7-pin plug. The red probe should fit into the top right slot of the plug. The ground or input is faulty if your multimeter is not reading anything.
Step 3: Check each light source
Leave the black probe in the ground socket of the plug while you check each bulb to see if any of its wiring is faulty. After that, insert the red probe into the first light socket. For the right brake light, use the middle right socket.
Then ask your partner to turn on the brake light. If the contact wiring is working properly, the screen should show 12 volts. If no results appear, the wiring for that light is no longer working.
Step 4. Check the turn signals, brake lights and reversing lights.
If the wires (in the previous test) are functioning, move the red probe to the next plug position and test the blinking, brake and reversing lights one at a time until all other potential problems have been ruled out.
Summing up
Contact a technician if the previous continuity test and a multimeter test with a 7-pin trailer connector did not solve your problem. The best part is that you can usually "do it yourself" fix the problem because these methods pinpoint the problem for you. (1)
The 7-pin trailer plug can be fixed. This is how the 7-pin trailer plug is attached. Buy a premium 7-pin trailer plug first. To see the wires, remove the old plug.
Each cable must be insulated. Connect the cable after connecting the center wire. The cable wires must be connected to the plug-in terminals. The plug assembly should now be assembled together. Check the stability of the fork body. (2)
Take a look at some of our articles below.
- How to test trailer headlights with a multimeter
- How to test a fluorescent light bulb with a multimeter
- How to test a three-wire coil on a plug with a multimeter
Recommendations
(1) DIY solution - https://www.instructables.com/38-DIYs-That-Solve-Our-Everyday-Problems/
(2) Housing Stability - https://home.treasury.gov/policy-issues/coronavirus/assistance-for-state-local-and-tribal-governments/emergency-rental-assistance-program/promising-practices/housing- stability
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