Parts Needed to Add 4-way and 7-Way to 1999 Chevy Express 3500  

Question:

Expert Reply:

Hey Bill! I can definitely get you the part numbers. Do you know if he has the factory tow package? That isn't something I can look up using the VIN number. If he does, you can use the Replacement OEM Tow Package Wiring Harness with 4-Pole Flat Trailer Connector # 118240.

If he does not, you will need the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C55335. Honestly, based on what we have seen lately I would say to install this wiring harness even if he has the factory connector. A lot of the old factory wiring ends up being a mess and doesn't work. This plugs into the tail light wiring harness so you won't have to worry about the tow package wiring being bad.

In addition to the 4-way you will also need the # ETBC7. This comes with everything you need to upgrade to a 7-way. The included adapter also maintains the 4-way functionality so he will have both connections. Once your 7-way is installed you can add a brake controller like the Tekonsha Prodigy P2 # 90885.

I added some installation videos below for your reference.

expert reply by: Robin H

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Prodigy P2 In Chevy Express
(click to enlarge)

Robin H.

10/30/2025

Hey Bill, how did the wiring setup go on that Chevy Express 3500? Did the Curt harness and ETBC7 kit make the install go smoothly? Your feedback could really help others working on similar vans.

Bill G.

10/30/2025

@RobinH EASY, PEASY..SIMPLY STRAIGHT FORWARD INSTALLATION. WILL BUY AGAIN