

🚛 Take control with GM precision – your trailer’s new best friend!
The GM Genuine Parts 20850923 Trailer Brake Control Module Assembly is a factory-recommended replacement part engineered to meet original equipment specifications. Designed and tested by General Motors, it guarantees reliable, durable performance and seamless integration with your GM vehicle’s trailer brake system, ensuring optimal safety and control on the road.










| ASIN | B0049HGOYG |
| Best Sellers Rank | #816,973 in Automotive ( See Top 100 in Automotive ) #456 in Automotive Replacement Power Brake Systems |
| Brand | GM GENUINE PARTS |
| Customer Reviews | 3.9 3.9 out of 5 stars (126) |
| Date First Available | October 27, 2010 |
| Exterior | Machined |
| Is Discontinued By Manufacturer | No |
| Item Weight | 13.4 ounces |
| Item model number | 20850923 |
| Manufacturer | ACDelco |
| Manufacturer Part Number | 20850923 |
| Model | Trailer Brake Control Module |
| OEM Part Number | 20850923 |
| Product Dimensions | 8.4 x 6.3 x 2 inches |
T**G
Works well, worth the money if you need to use the trailer brake
I bought a 2009 Silverado 2500 at auction and come to find out the entire trailer brake control module and relay were missing. Ordered this and it was at my doorstep as expected. Install was painless, no complaints. After installed got fault code C1114, then realized I had to get it programmed by a local automotive ECM/programming shop for $100 so budget at least this as the local Chevrolet dealer wanted $160
J**S
Good
Good
C**.
Needs to be programmed
I was unaware that this part needs to be programmed to buy a local Chevy dealer before it can be used. Make sure you have your old one first. Returning mine as I don't want the extra added expense
A**R
Was the right part for repair
This module was the exact replacement of the original. I took to a GM dealer after I installed so they could program the new module. This fixed my trailer brake issue.
D**D
Perfect fit
Perfect quality and was as described properly in the description. I would recommend this product to somebody who is looking for one.
L**S
works fine, if...
So, this module works as expected and the price is great, I even opted for a cheaper used model and paid like $21. That being said, you will have to have it programmed to your vin number, or you'll continue to get "Service Trailer Brake" displays on your DIC and / or no gain, or manual switch operation. If you expect to install and have everything working right away, you will be upset. If you're trying to minimize the overall cost by having the hardware already installed , this worked for me. GM+plus wanted $265 by mail and my local Chevy service department wanted $399 for a repair I dropped $89 on using this product, an SSR and a local tuner that programmed the module in 5 minutes.
M**N
Worked as expected, needs programming
Worked as expected 08 Chevrolet 2500 Duramax to fix service trailer brake error. Just remember it needs to be programmed. I used a generic J2534 passthrough and GM TDS.
B**F
Lasted 7 months
Bought in February 2025, need a replacement by September 2025?
A**N
Quick easy install plug and play and genuine oem ac Delco bag it came in and definitely a lot cheaper than the dealer that are selling them for almost 400$
R**N
Good value for the price
B**N
Needs to be flash programmed at GM dealer
A**R
Works as supposed to Needs programming
J**.
la pieces n'etais pas le probleme
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