Why Doesnt Tow-Ready #118381 Harness Work on a 2008 Jeep Grand Cherokee With a Factory 7-way

Updated 05/28/2013 | Published 05/22/2013

Question:

I have a 2008 Jeep Grand Cherokee Ltd that does not have a trailer hitch and does not show a tow package on the sticker, but it does have the factory tow 7 way connector under the center of the rear bumper that would seem to indicate that the factory tow wiring is in place. I installed the 118381 wiring harness which plugged into the connector perfectly, but while the vehicle lights function o.k., I have no function from the 4 pin connector on either running lights or brakes or stop lights. I read somewhere else that after installing this 118381 harness on a vehicle without the tow package you had to take the vehicle to a dealer to have it re-programmed to get the trailer light functions. Is this correct, or are there missing fuses, etc that are also preventing this harness from working?

asked by: Harold P

Expert Reply:

There are two ways to get your trailer lights working on your 2008 Jeep Grand Cherokee. The first way is as you thought - take the vehicle back to the Jeep dealer and have them activate (reprogram) the internal Jeep computer to activate the tow package wiring.

An alternative choice is re-wiring your vehicle with the Universal Installation Kit # ETCB7 and T-One Vehicle Harness # 118425 by Tow Ready. I have attached an install video of this harness on a 2008 Jeep Grand Cherokee and also a controller installation video. With these two products, you will not have to take your vehicle to the dealer for re-programming.

By installing the # 118425 it will bypass the non-functioning tow package wiring and will also provide you a working 4-pole. If you need a fully functional 7-way, then the ETCB7 kit includes the # 37185 that you originally referenced.

expert reply by: Lori W