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Where’s my trailer brake relay?

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21K views 5 replies 3 participants last post by  jdwarren  
I
#1 ·
2018 2500HD
Getting the service trailer brake system message on dash intermittently, but over and over again (if that makes sense).

Was driving me nuts last time it was happening; I was puking a trailer with 7-pin connector but the trailer
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has no brakes (<3k GVW snowmobile trailer).

I bought a trailer brake relay from Rock Auto and have looked all over underneath the spare tire area and don’t see anything that looks like it. I also don’t see anything mounted to the frame rails like on the older models.
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#2 ·
I believe it's above the BCM, which is this metallic object. It's only held in by two or three bolts. Remove them and when you pull it down you should be able to see it. You may also have to disconnect the big wiring harness like I did.

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I
#3 ·
Thanks! I actually did remove that, thinking the relay would be hidden on top…which it very well might be, but what’s hidden behind that BCM doesn’t look anything like my relay or share the same hole spacing. I’m starting to think I’ve got the wrong part for my year truck and I need to go back to the drawing board and do some more research.
 
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