Control Resonant: Maintenance Protocol Quest Walkthrough (All Bulb Locations)

TL;DR:

• Maintenance Protocol starts automatically after Zoe’s Briefing at the Watchtower.
• Head to Deepest Underpass and enter the old Oldest House door using Morse code: dot, dot, dash (the word “in”).
• Watch the projector briefing, then use the switchboard to reveal three bulb locations.
• Fix the Volatile Bulb by talking it down and clearing the Hiss wave.
• Fix the Botanophobic Bulb by destroying every piece of Mold and fungal growth near it.
• Fix the Electrosensitive Bulb by throwing all three battery generators into the abyss.
• Return to the projector room, enter the slide, and select Break the bulb to complete the quest.
• Reward: Standard Issue Coverall outfit.

Maintenance Protocol is one of the most memorable side quests in Control Resonant. What starts as a simple alarm investigation turns into a multi-part bulb repair job where every light bulb has feelings, anxieties, and very specific demands. This guide walks you through every step — including the exact Morse code, all bulb solutions, and the slide sequence at the end that catches most players off guard.

control resonant maintenance protocol quest

Maintenance Protocol Quest Overview

Type: Side Story

Zone: Underpass

Requirement: Complete Zoe’s Briefing (unlocked after The Hedron Link)

Starting Location: Central — Watchtower

Reward: Standard Issue Coverall (cosmetic outfit)

Quest Description: An alarm is going off in the Oldest House’s lowest sections, triggered for the first time in decades. Dylan needs to find out what is wrong.

This quest is unlocked alongside New Growth at the same Watchtower briefing. If you are working through the Park side quests at the same time, our guide on whether to turn in Dr. Underhill in the New Growth quest covers that companion questline in full.

Maintenance Protocol Quest Objectives

• Investigate the Oldest House Alarm
• Find the Light Bulb Coordinates
• Fix the Volatile Bulb
• Fix the Botanophobic Bulb
• Fix the Electrosensitive Bulb
• Complete the Final Step at the Projector Room
• Fix the Final Light Bulb
• Escape the Slides

Step 1 — How to Start Maintenance Protocol

Maintenance Protocol starts automatically when you speak with Zoe during the side quest Zoe’s Briefing. She mentions an alarm going off deep in the Oldest House — something that has not triggered in decades. The quest drops straight into your Quest Log.

If you have not done Zoe’s Briefing yet, you need to complete The Hedron Link main mission first. After that, find Zoe at the Watchtower and the briefing begins. Both Maintenance Protocol and New Growth unlock at the same time from that one conversation.

Before heading down into the Underpass, make sure your Reach ability is equipped. You will need it to climb a specific wall early in this quest.

Step 2 — Investigate the Oldest House Alarm

Track the quest in your log. Fast travel to the Deepest Underpass fast travel door. This is in Underpass 5, which is the deepest section of the zone. If you have not activated this fast travel point before, expect a longer descent.

From the fast travel door, look south. There is a ledge you can climb using Reach. At the top, you will find a set of sealed security doors labeled “Door to ‘old’ Oldest House.”

Interact with the door to speak with Zoe over the radio. She pulls up an old manual and tells you the door requires a Morse code input.

Maintenance Protocol Morse Code Solution — How to Open the Old Door

The code is the Morse representation of the word “in.”

Enter: dot, dot, dash — two short inputs followed by one long one.

A common mistake here is entering it backwards as dash-dot-dot. That is incorrect. It is always two short, then one long. Use the keypad to the left of the door to enter the code and it will unlock.

Step 3 — Reach the Projector Room

Once the door opens, head inside. The first room has Mold enemies — clear all of them before going through the door to the south. Then follow the path up into the projector briefing room.

Wait for the video to finish playing. The projector shows an FBC maintenance worker explaining the situation: several light bulbs have come loose from their sockets and are destabilising the facility. The solution, according to the film, is to tighten each bulb three times — “righty-tighty.”

Step 4 — Find the Light Bulb Coordinates

After the film ends, move into the adjacent switchboard room. Interact with the console by the three red lights. This marks three bulb locations across the Underpass on your map.

Your log updates with three new objectives: Volatile, Botanophobic, and Electrosensitive. You can tackle them in any order. The table below summarises what each one needs before you can tighten it:

• Volatile Bulb — east of Halfway Trail — calm it with dialogue, then clear a Hiss wave
• Botanophobic Bulb — north of the Research Site — destroy all Mold and fungal growth nearby
• Electrosensitive Bulb — below the Research Stations fast travel door — throw all three battery generators into the abyss

The rule is the same for all three: the tighten prompt does not appear until the bulb’s specific condition is met. If you walk up to one and nothing happens, something in the room is still bothering it.

Step 5 — How to Fix the Volatile Bulb

Fast travel to Halfway Trail. Follow the waypoint east to find the Volatile Bulb hanging over a set of red hazard floor tiles.

This bulb is anxious and needs to be talked down before it will let you touch it. Interact with it and choose the calming dialogue options:

• Round 1: “Time to be tightened” → “You seem stressed” → “It’s okay, you’re okay”

After the first set of dialogue, a wave of corrupted Hiss enemies spawns in the area. This is the bulb’s anxiety made physical. Fight them off while reassuring the bulb. Interact with it again mid-combat and pick:

• Round 2 (during/after the wave): “I’ll keep them away from you”

Once the enemies are dead, interact with the bulb one final time and choose:

• Round 3: “Stop worrying” → “You deserve to be fixed”

The tighten prompt appears. Twist the bulb three times to settle it. The Volatile Bulb is done.

Step 6 — How to Fix the Botanophobic Bulb

Head to the island north of the Research Site area. Follow the path marked on your map and climb the shifting concrete structures to reach the Mold-overgrown chamber.

The Botanophobic Bulb is afraid of plants — specifically the Mold surrounding it. It will not allow you near until the room is completely clear.

• Destroy every piece of Mold, every fungal growth, and every explosive spore in the chamber.
• Do not miss any. The check requires the entire room to be clear — even one surviving growth will block the prompt.

Once the area is completely clean, walk up to the bulb and twist it three times. Botanophobic Bulb: done.

Step 7 — How to Fix the Electrosensitive Bulb

Fast travel to the Research Stations fast travel door. The Electrosensitive Bulb is located directly below this door. Cross the geometric platforms toward the research site to reach it.

This bulb hates electricity. There are three red portable battery generators placed around the room near it. Your task is simple:

• Pick up each generator.
• Carry or throw each one over the ledge into the abyss.
• They must go fully off the edge — dropping them on the floor nearby is not enough.

Move all three charges away using the same method you use to transfer Power Core charges elsewhere in the game. With every electrical source gone, the interact prompt appears. Twist the bulb three times. Electrosensitive Bulb: done.

If the power mechanics across the Underpass have been causing you trouble in other quests, our Central Checkpoint power puzzle guide and how to restore power in the House in Distress cover the core charge mechanics in detail.

Step 8 — Return to the Projector Room

With all three bulbs fixed, head back to the projector room near the old Oldest House door. Take the overhead cable car and retrace the Underpass pipes back to the starting area. Fast travel to Deepest Underpass if you want to skip the travel.

The maintenance worker reappears on screen. This time, the film reveals that a fourth bulb is trapped inside the projection itself. The worker invites you to touch the screen. Walk up and interact with the projection.

Step 9 — Escape the Slides (Fix the Final Bulb)

Dylan is pulled into the slide and becomes a flat, black-and-white cartoon version of himself. The world around him is a 2D animated FBC film reel. This is the quest’s finale — and it is unlike anything else in Control Resonant.

Work through the dialogue prompts. You will encounter the Board’s cryptic inverted-triangle messages along the way. Keep selecting options until “Break the bulb” becomes available.

When it appears, select it. Dylan produces a crowbar and smashes the unstable cartoon bulb. The projection collapses and he lands back in the three-dimensional projector room.

The dialogue sequence to get there in order:

• “Where are you going?”
• “Unstable bulb”
• “Do you know a way out?”
• “Break the bulb”

The Quest Completed banner appears. The Standard Issue Coverall outfit lands in your inventory automatically and goes straight to your Wardrobe — it is a cosmetic only, with no gameplay effect.

Maintenance Protocol Reward

• Standard Issue Coverall — cosmetic outfit, available in Dylan’s Wardrobe immediately on completion

Common Mistakes to Avoid

• Wrong Morse code: It is dot-dot-dash, not dash-dot-dot. Two short, one long. Double check before entering.
• Tightening too early: The prompt simply will not show until each bulb’s condition is fully met. If nothing happens when you approach, there is still something in the room bothering it.
• Leaving one Mold growth at the Botanophobic Bulb: The check covers everything — including the explosive spores, not just the large Mold clusters.
• Dropping generators on the floor: They must go over the ledge into the abyss. Placing them on the floor beside the ledge does not clear the electrical condition.
• Missing the cable car back: After fixing all three bulbs, the cable car is the fastest route back to the projector room. Look for it overhead in the Underpass after fixing the Electrosensitive Bulb.

Other Guides for This Part of Control Resonant

If you are working through the Underpass region and The Park at the same time, these will help:

• The Subway Fault — how to reach the ability
• How to reach the Unknown Zone
• Urban Survival quest walkthrough
• Crossing the Threshold walkthrough
• Panopticon Service Request quest guide
• Konstig painting puzzle solution
• All Power Upgrade chest locations

Thinking about your build going into quests like this? Our how to respec guide explains how to redistribute Talent Points between fights.

Frequently Asked Questions

Control Resonant is available on the official Control website, PlayStation Store, Xbox Store, Steam, and Epic Games Store.