Why do brakes need to be replaced in the first place?

Friction material on the brake pad contacts the rotors to slow the vehicle. In time, that material wears away and the pads must be replaced. Sometimes the rotors and calipers must also be replaced.

What’s the squealing sound I hear when braking?

Over time, wear indicators in brake pads may contact the rotors’ surface when braking, resulting in a metallic squealing sound. Vehicles equipped with wear sensors may also provide an alert that minimum brake pad thickness has been reached.

What if it’s more of a grinding sound?

If all the friction material has been worn away, the metal backing plate of the brake pad will be the material in contact with the rotor during braking. It causes a grinding sound and braking performance is often diminished.

Why do the brakes seem to pulsate when stopping?

It may be due to worn brake pads, unevenly worn rotors or unevenly worn tires. Have the pulsation diagnosed as soon as possible to avoid the possibility of greater brake system wear or damage.

What about vibrations or shaking in the steering wheel?

This is more serious than pulsation. If the brakes are very worn or the rotors are unevenly worn, there can be a significant vibration or shaking in the steering wheel when braking. It may mean brake service is needed immediately.

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GM Genuine Parts 20904439 Trailer Brake Continue Relay Assembly

GM Genuine Parts 20904439 Trailer Brake Continue Relay Assembly

Product ID: 25310175

Details

Connector Type
Screw
Contact Material
Silver
Contact Type
Online_sales
Mounting Type
None" or "PCB
Brand
GM GENUINE

📏Compact 4.4 x 3 x 1.2 inch design fits seamlessly

🔩Screw connector type ensures secure installation

⚙️Silver contact material for superior conductivity

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€ 96.46

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Sold byAmazon SpainDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

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Description

🚛 Elevate your trailer brake game with GM Genuine precision!

SEAMLESS COMPATIBILITY - Specifically crafted for Chevrolet, Buick, GMC, and Cadillac vehicles
DURABLE SILVER CONTACTS - Enhanced conductivity and corrosion resistance for long-lasting reliability
EFFORTLESS INSTALLATION - Screw connector type for a secure, hassle-free setup
PRECISION ENGINEERED OE QUALITY - Designed and validated by GM engineers for flawless trailer brake control
RELIABLE ELECTRO MECHANICAL SWITCHING - Robust coil and contact points deliver consistent brake relay performance

The GM 20904439 Trailer Brake Continue Relay Assembly is an OE-quality, electro-mechanical relay designed and rigorously tested by General Motors engineers. Featuring durable silver contacts and a secure screw connector, this compact relay ensures reliable trailer brake control specifically for Chevrolet, Buick, GMC, and Cadillac vehicles. Backed by GM Genuine Parts standards, it integrates seamlessly with your vehicle’s braking system for enhanced safety and performance.

Specifications

ASIN	B00559VPK0
Best Sellers Rank	#39,410 in Automotive ( See Top 100 in Automotive ) #8 in Trailer Brake Assemblies
Brand	GM GENUINE PARTS
Brand Name	GM GENUINE PARTS
Connector Type	Spade
Contact Material	Silver
Contact Type	Online_sales
Customer Reviews	4.7 out of 5 stars 2,156 Reviews
Global Trade Identification Number	00707773710814
Included Components	20904439
Item Type Name	RELAY ASM-TRLR BRK CONT
Manufacturer	ACDelco
Model	20904439
Mounting Type	None" or "PCB Mount
Operation Mode	Automatic
Part Number	20904439
UPC	707773710814
Unit Count	1.0 Count
Warranty Description	24 Month / Unlimited Mile Limited Warranty on parts sold on or after 04/01/18. (Parts Only) Please see ACDelco.com for more details.
Wattage	1.73 watts

Reviews

K**R

Exact fit , works great !

This worked great ! Took away the service trailer brake and check trailer brake wiring warning light and annoying dinging on my 2012 Chevy Silverado. Easy to install. Exact part match. Fit perfect !

17.02.2026

J**F

Good results.

Works great for fair price. Good

1.04.2026

H**E

simple fix to annoying service trailer brake light easy

fixed the issue ..i have had a service trailer brake light message on for over a year its on a 2013GMC Sierra i don't use trailer brakes so was not worried much just annoyed at light on all the time .i started looking on line for problems that might happen and most were saying bad wire or plug .after tracing out all the wires and checking the plug i found nothing wrong so then i decided to ask the dealer GMC there thinking on it .all i got from dealer was bring it in and we can check run test for about 400 plus parts and later found that these parts are a problem and they new this and never told me there was a bulletin out from GMC( ripoffs ).so i said no thanks .so back to the web and seen this part on amazon checked thru the reviews and decided to change part .most people said easy change and fixed the problem of service trailer brake .from start to finish it took 10 minutes to install .all i had to do was lower spare loosen 2 star screws remove plug and install new .it was that easy it took longer for me to find my star driver then to change the part .so if you have the same issue i would first just look at the wires for something torn loose ya never know ,and start with this part first .i am 100 percent pleased and everything is working perfect no more service trailer brake light .easy fix thanks for everyones post hope this one helps .also the part fits many years GMC /chevy models trucks and cars .

11.05.2025

A**R

OEM quality

My 08 Silverado 2500 had the “service trailer brake system” light on the dash. All fuses good, and the brake controller was working properly by being able to adjust trailer braking power. Only thing really left was the relay. This is a real GM part, took 5 mins to install, no more service light.

8.04.2025

M**.

Saved a lot of money

Got for a 2007 new body style chevy 2400 hd. Had the check trailer break system alarm on the dash. Got this and the fuse and fixed my problems. worked like a charm. Only reason for 4 star is the mounting holes do not work, they are too small for stock bolts. I ended up zip tying to frame and worked like a charm. I'm certain this fix saved me a lot of money at the stealership.

2.11.2016

B**R

Works perfect

23.11.2025

J**S

Good

2.01.2026

T**N

Did what it should

Did exactly what it should do and was easy to install , fit well and use , great quality and we have trailer brakes!

4.08.2024

S**E

Fast Delivery

Fast delivery and correct part but did not fix my "Service Trailer Brake" intermittent issue.

5.08.2020

R**A

Good replacement part

Good replacement part and was easy to install. Works great.

1.02.2024

L**I

Works

Works fixed a trailer brake fault on my 07 chev 2500hd

8.02.2025

J**N

Exact fit

Identical to the original, just wish it came with new screws.

25.01.2022

M**E

Perfect fit

Easy installation 2007 duramax fixed service trailer brake system issue.

12.04.2023

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