If you’re using a Tow-Pro Elite V2 or V3 with a Universal Wiring Kit (TPWKIT-013 or TPWKIT-014) or an EPDK-001 and notice issues such as trailer warning lamps, fast-flashing indicators, brake light fault codes, or reverse sensors/cameras not working when no trailer is attached, the Encapsulated Protection Device may need testing.
After confirming the wiring is correct and undamaged, unplug the Encapsulated Protection Device and use a multimeter with a diode test function.
REDARC recommends seeking the support of a qualified auto electrician or technician.
Important
In this article we explain the need for testing to determine the cause of the issue. Testing may involve changes to the installation or wiring. For your safety and accuracy, REDARC recommends engaging a REDNetwork member or a suitably qualified auto electrician - Find Your Local Installer
This information is applicable to the following:

- Tow-Pro Elite V2 (EBRH-ACCV2)
- Tow-Pro Elite V3 (EBRH-ACCV3)
- Universal Wiring Kit (TPWKIT-013)
- Universal Extended Wiring Kit (TPWKIT-014)
- Encapsulated Protection Device (EPDK-001)
Required tools
- Multimeter that has a diode test function (indicated by red circle and arrow in image)

When would I need to test the Encapsulated Protection Device?
If your vehicle has the Tow-Pro Universal Wiring Kit installed (TPWKIT-013 or TPWKIT-014) or has an EPDK-001 installed and you are experiencing some or all of the listed issues when no trailer is attached, it could result in a wiring issue or damaged Encapsulated Protection Device.
Possible vehicle symptoms
- Trailer warning lamp on with no trailer detected
- Dashboard indicator pilot light flashing at a faster rate
- Logged fault codes relating to brake light circuits
- Reverse sensor/alarm does not operate
- Reverse guidance/camera does not function correctly
How to test the Encapsulated Protection Device?
To test the Encapsulated Protection Device, it will require diagnostic testing. REDARC recommends seeking the support of an installer where possible, however please see the diagnostic steps below.
Testing the signal conditioning model
Once you have confirmed that any of the issues listed above (see possible vehicle symptoms) are occurring, prior to testing the Encapsulated Protection Device check the following:
- If a Tow-Pro Universal wiring kit was used, review the User Manual, see – TPWKIT-014 User Manual or TPWKIT-013 User Manual, and confirm installation is correct.
- If a wiring installation using the EPDK-001, refer to the diagram below and ensure wiring is correct.
- Review wiring, looking for damaged or squashed wiring harness or any visible damage.
- If everything looks good, refer to next test.

How to test the Encapsulated Protection Device?
Unplug the Encapsulated Protection Device from the wiring harness/installation, then using a multimeter, refer to the following test procedure:
1. Using a multimeter with a diode test function, set to diode test.
Note, most multimeters will require you to select it and press a mode button.
2. Connect the multimeter Positive lead (red) into the pin labelled Vehicle Pin and negative lead (black) into the pin labelled Tow-Pro (indicated on the Signal Conditioning Module)
It should read open circuit (OL or OC).

3. Connect the multimeter negative lead (black) to the Vehicle Pin and the positive lead (red) to the Tow-Pro Pin (indicated on the Signal Conditioning Module)
It should read a voltage approx. 0.145V.

4. If the outcomes listed in steps 2 & 3 are confirmed, this indicates that the signal conditioning module is working correctly and is not the cause of the symptom.
5. If the outcome from the testing results in step 3 results in short circuit or open circuit, this indicates that the Signal Conditioning Module is faulty and needs replacing.
If you reach step 4 & 5 and are unable to trace or address the issue, further diagnostic testing is required by a specialist and REDARC recommends seeking the support of an installer.