How to Make RAM Tow Mirror Lights Stay On: 10-Step Guide
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If your RAM tow mirror lights only illuminate when you use the turn signal, unlock the truck, or trigger another factory function, you may want them to remain illuminated while driving.
The challenge is that these lights can be controlled by the vehicle’s Body Control Module (BCM) and may have different functions depending on the RAM model and year. A setup that works on one truck may not behave the same way on another.
The good news is that the information covered in the available RAM wiring discussions points to several practical approaches, including a 12V power connection, relay-controlled circuit, manual switch, or a diode-and-resistor arrangement.
Before touching the wiring, identify your exact RAM model and year and understand which lights you want to keep illuminated.
What You Need Before Starting
Tools and Materials
Prepare the following items where applicable:
- 18–22 gauge automotive wire
- Wire stripper and crimper
- Multimeter or test light
- Screwdrivers
- Pliers
- Electrical tape
- Heat-shrink tubing
- Heat gun
- Soldering iron
- Wire connectors
- Zip ties
- Relay
- Fuse
- Manual switch
- Resistors
- 1N4007 diodes
- Flashlight
- Vehicle wiring information
You may not need every item. The exact materials depend on whether you use a relay/switch setup or the diode-and-resistor approach.
10 Steps to Keep RAM Tow Mirror Lights On
1. Identify Your RAM Model and Year
Start with the exact truck configuration.
The available information mentions RAM 1500, 2500, and 3500 models, and the forum discussion includes examples from 2009, 2012, 2015, 2016, 2018, 2019, 2020, 2021, and 2022 trucks.
This matters because wire colors, factory functions, and module behavior can differ.
Do not assume that a wire color shown for one RAM will be identical on another model.
2. Decide Which Light Function You Want
Before modifying anything, determine whether you want:
- Marker/running illumination
- Turn-signal operation
- Puddle-light operation
- Or a combination of functions
The turn signal needs to retain its flashing function. Simply forcing every circuit to remain continuously powered can interfere with how the light is supposed to operate.
3. Disconnect the Battery Before Wiring
Electrical work should begin with the truck safely parked and the electrical system protected.
Disconnect the battery before exposing or modifying wiring. Keep the working area organized and avoid pulling aggressively on the mirror harness.
This simple step reduces the chance of an accidental short while you are working.
4. Access the Tow-Mirror Wiring
Carefully remove the necessary mirror or door-panel trim to reach the wiring harness.
One approach describes exposing approximately 3–4 inches of harness so the individual wires can be identified and tested.
Use a plastic trim tool where appropriate and take your time. Breaking a clip or damaging the harness can create a bigger repair than the original lighting problem.
5. Identify the Correct Circuits With a Meter
Do not identify a wire by color alone.
Use a multimeter or test light to determine which circuit provides the required signal.
The wiring approach described in the available material uses a 12V signal for identification. The parking-light circuit should provide the appropriate constant signal when the lights are activated.
Test before making any permanent connection.
6. Choose Your Power-Control Method
There are two important approaches described in the material.
Ignition-Controlled Power
An ignition-switched source allows the Mirror light to operate when the truck is running.
This can reduce the chance of accidentally leaving the lights powered while the vehicle is parked.
Constant 12V Power
An always-hot 12V source can allow the lights to operate whenever the circuit is switched on.
However, leaving the lights powered for an extended period can contribute to battery drain.
For that reason, a switch or another form of power control is important.
7. Use a Relay and Switch When Appropriate
A relay can allow a lower-current control signal to operate the mirror-light circuit.
The general arrangement is:
Switch → relay → mirror-light circuit
The switch gives you manual control, while the relay handles the controlled electrical load.
A fuse should also be incorporated where appropriate to provide circuit protection.
8. Consider the Diode-and-Resistor Method
Another approach described for the RAM tow-mirror modification uses a combination of:
Parking light → resistor → diode → mirror turn-signal circuit
The resistor is used to reduce brightness during running-light operation, while the diode helps prevent unwanted electrical back-feeding between circuits.
The material specifically mentions 1N4007 diodes and 18–22 gauge wiring.
Do not simply connect the parking-light and turn-signal wires directly together. The two circuits need to remain properly controlled.
9. Test the Lights Before Reassembling Everything
Testing should happen before you put the mirror and door components completely back together.
Check the following:
- Parking/running lights operate as intended.
- Turn signals still flash.
- Mirror Lights do not flicker.
- Connections remain secure.
- No unexpected lights illuminate.
- The circuit does not behave differently when the truck is locked or unlocked.
With the diode/resistor arrangement described in the material, the expected behavior is reduced-brightness illumination during the running-light function and brighter flashing when the turn signal is activated.
10. Secure the Wiring and Test Again
Once the circuit works correctly, protect the connections.
Use heat-shrink tubing, electrical tape, and zip ties where appropriate. Keep wiring away from locations where it could be pinched, pulled, or exposed unnecessarily to moisture.
Then reinstall the mirror and trim carefully and perform another complete lighting test.
Testing twice is much easier than removing the door panel again later.
What About AlfaOBD?
The RAM forum discussion also explores AlfaOBD and the vehicle’s CBC Features.
One setting discussed was:
Side Mirror Repeaters Used as Side Markers — Y/N
Another setting relates to whether mirror turn signals are present.
However, the reported results were not consistent across the trucks discussed. One owner left the setting enabled for more than 24 hours, planned to test it for 1 week, and later reported no result after approximately 3 weeks.
Another 2019 RAM 1500 owner also reported no change after enabling the setting.
So, software configuration should not automatically be assumed to activate continuous mirror lighting on every RAM.
RAM Model Differences Matter
The forum discussion includes several different configurations, including:
- 2015 RAM 5.7 Hemi
- 2016 RAM 1500 Sport 5.7 Hemi
- 2020 RAM 2500 Bighorn 6.4
- 2021 DS 5.7 Hemi
- 2022 RAM 3.6 V6
- 2012 RAM 5.7
- 2019 RAM 1500
- 2016 and 2018 RAM 2500
- 2009 RAM 5.7 Hemi
One particularly useful report describes a 2020 RAM 2500 Bighorn where the mirror lights reportedly operated as running lights and turn signals from the factory.
That shows why checking your exact configuration is important before making modifications.
A $20 Conversion Was Also Reported
The RAM discussion includes a $20 conversion option for certain 2016 and 2018 RAM 2500 applications.
The described conversion was intended to make the mirror signal lights operate as running lights.
Another reported setup used a 12V wire that always has power and allowed the mirror lights to remain illuminated with different headlight/DRL conditions.
These are forum-reported experiences, so they should not be treated as universal instructions for every RAM.
Things to Avoid
1. Do Not Guess Wire Colors
Wire colors can vary according to the model year and RAM configuration.
Always verify the circuit with a meter or appropriate wiring information.
2. Do Not Join Circuits Directly Without Understanding Them
Connecting the parking-light and turn-signal circuits directly can create unwanted electrical interaction.
The diode/resistor approach specifically addresses this issue.
3. Do Not Ignore Battery Drain
An always-hot 12V connection can leave the lights powered when the truck is parked.
A switch or ignition-controlled source can help prevent unnecessary battery drain.
4. Do Not Skip Circuit Protection
A fuse and properly selected relay can provide important protection for a modified circuit.
5. Do Not Leave Connections Exposed
Moisture and movement around a door or mirror can eventually cause connection problems.
Protect wiring with appropriate insulation and secure it properly.
6. Do Not Rush Door-Panel Removal
The wiring may be easier to reach than it looks, but forcing trim pieces can cause unnecessary damage.
Take your time and keep track of clips and fasteners.
Quick Troubleshooting
If the mirror lights do not stay on after the modification, check these points in order:
| Problem | What to Check |
|---|---|
| No light | 12V power source and fuse |
| Flickering | Loose connector or wiring |
| Turn signal stops working correctly | Circuit connection and diode arrangement |
| Lights remain on when parked | Constant-power connection or switch |
| Different behavior between sides | Driver/passenger wiring |
| Software setting has no effect | RAM model/year and factory configuration |
| Dim or inconsistent lighting | Resistor, connection, or power source |
Frequently Asked Questions
Can RAM tow mirror lights stay on continuously?
They can be modified for continuous illumination, but the exact method depends on the RAM’s wiring, model year, factory configuration, and desired light function.
Does the modification use 12V power?
Yes. The described approaches include 12V power or signal connections, with either constant or ignition-controlled power depending on the setup.
Will the turn signal still work?
A properly designed circuit should preserve the turn-signal function. The diode/resistor approach is specifically described as allowing running-light illumination while retaining brighter turn-signal flashing.
Can AlfaOBD activate the lights?
The forum discussion reports mixed results. The discussed CBC mirror-repeater setting did not produce the desired result for several users.
Can constant power drain the battery?
Yes. If the mirror lights remain connected to an always-hot power source and stay illuminated for an extended period, they can contribute to battery drain.
Is a relay necessary?
A relay is useful when a separate control switch needs to control the mirror-light circuit. The exact requirement depends on the electrical design being used.
Final Thoughts
Making RAM tow mirror lights stay on is less about connecting one random wire and more about understanding how the truck’s lighting circuits work.
The key numbers to remember are 12V, 18–22 gauge wire, approximately 3–4 inches of accessible harness for the described wiring approach, 1N4007 diodes, and the reported $20 conversion example for certain RAM 2500 applications.
Most importantly, verify your specific RAM model and year, test every circuit before making a permanent connection, protect the wiring, and consider an ignition-controlled source if you want to reduce the possibility of battery drain.
A careful installation can make the lighting behavior more useful while keeping the truck’s original signaling functions in mind.
Dylan
Dylan is a lighting enthusiast and experienced content creator with 7 years of expertise in blogging about home improvement, lighting solutions, and modern illumination trends. As the lead writer for BrightLightZone, Dylan focuses on simplifying complex lighting topics and helping readers discover practical, energy-efficient, and innovative lighting ideas for their homes and spaces.
With a passion for exploring the latest advancements in LED technology, smart lighting, and DIY lighting solutions, Dylan combines research, creativity, and real-world insights to create helpful guides for homeowners, DIY enthusiasts, and lighting lovers. Through BrightLightZone, Dylan aims to inspire people to transform their environments with smarter, brighter, and more sustainable lighting choices.
