electrical

Main Relay

for 2023 Chevrolet Bolt EUV 65 kWh Single Motor FWD · FWD

Editorial review:Chris Hackleman — Master Technician · 20+ years · Jeff Moore — Master Lexus & Toyota Mechanic · 20+ years

Difficulty

Moderate

Time

30 min

Tools

Steps

✓Expert-verified. Personally reviewed and approved by OLP's master technicians (Chris Hackleman & Jeff Moore — 20+ years each). Always follow the vehicle's factory service information and torque specs.

Replace the main power relay that controls high voltage system activation in the 2023 Chevrolet Bolt EUV electric vehicle.

Warnings

⚠️High voltage components present. Ensure 12V battery is disconnected and wait 5 minutes before starting work. Do not touch orange high voltage cables.

⚠️Verify system is de-energized with multimeter before touching any components in the power distribution area.

⚠Main relay failure can prevent vehicle from powering on. Ensure replacement relay is correct part number for 2023 Bolt EUV.

Tools required

10mm socket and ratchetEssential

8mm socketEssential

Torque wrench (5-20 Nm range)Essential

Insulated gloves rated for high voltage workEssential

Digital multimeterEssential

Plastic trim removal tools

Wire brush for cleaning contact surfacesEssential

Dielectric grease

Parts

Main power relay assembly × 1 — Use OEM specification

Preparation

Park vehicle on level surface and engage parking brake
Turn off vehicle and remove key fob from interior
Open hood and secure with prop rod
Disconnect negative 12V battery terminal and isolate cable
Wait minimum 5 minutes for capacitors to discharge
Locate main relay assembly in underhood power distribution center on driver side

Procedure

1
Remove power distribution center cover
Remove the plastic cover over the underhood power distribution center by loosening the cover screws. Set cover and screws aside in clean workspace.
Torque spec
Cover Screws11 Nm (8 lb-ft)
2
Verify system de-energization
Use digital multimeter set to DC voltage to verify no voltage present at main relay terminals. Check between relay power terminals and ground. Reading should be 0V.
⚠️If voltage is detected, do not proceed. Investigate why system has not de-energized properly.
3
Disconnect electrical connectors
Press release tab on main relay connector and carefully pull connector straight off relay. Note orientation of connector for reinstallation. If connector has locking screw, remove it first.
Torque spec
Connector Screws4 Nm (3 lb-ft)
4
Remove relay mounting hardware
Remove the mounting bolts securing the main relay to the power distribution bracket. Support relay with one hand while removing final bolt to prevent dropping.
Torque spec
Module Mounting Bolts8 Nm (6 lb-ft)
5
Remove main relay assembly
Carefully lift main relay straight up and out of mounting location. Avoid contact with surrounding components. Inspect mounting bracket and connector for corrosion or damage.
⚠Do not force or pry relay if it does not lift easily. Check for additional fasteners or clips.
6
Clean mounting surfaces and terminals
Use wire brush to clean relay mounting bracket contact surfaces and ground contact points. Remove any corrosion, dirt, or oxidation. Wipe clean with lint-free cloth. Inspect connector terminals for damage or corrosion.
ℹ️Poor ground contact is a common cause of relay failure. Ensure all contact surfaces are clean and bare metal.
7
Install new main relay
Position new main relay into mounting bracket, aligning bolt holes. Ensure relay is fully seated against mounting surface with no gaps. Apply dielectric grease to connector terminals if desired.
⚠Verify relay part number matches original before installation. Incorrect relay can cause system damage.
8
Install relay mounting bolts
Install mounting bolts finger-tight first to ensure proper alignment. Torque bolts in a crossing pattern to specification to ensure even clamping force.
Torque spec
Module Mounting Bolts8 Nm (6 lb-ft)
9
Reconnect electrical connector
Align connector with relay terminals and press firmly until click is heard indicating full seating. If connector screw is present, install and torque to specification. Verify connector lock tab is fully engaged.
Torque spec
Connector Screws4 Nm (3 lb-ft)
10
Reinstall power distribution cover
Position cover over power distribution center, aligning all mounting points. Install cover screws and torque to specification in a crossing pattern.
Torque spec
Cover Screws11 Nm (8 lb-ft)
11
Reconnect 12V battery
Reconnect negative battery terminal and torque terminal bolt to specification. Ensure terminal is clean and making solid contact.
⚠Do not overtighten battery terminal. Excessive torque can damage battery post.
Torque spec
Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

Ensure all electrical connectors are fully seated and locked
Verify no tools or parts are left in engine compartment
Confirm power distribution center cover is properly secured

Verification

Press brake pedal and press power button to start vehicle in READY mode
Verify instrument cluster displays no warning lights related to propulsion system
Check that READY indicator illuminates confirming high voltage system is active
Test drive vehicle briefly to confirm normal operation and acceleration
If any warning lights appear, retrieve diagnostic codes to verify relay installation

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