Merchant Automotive 10686 Pass Through Trans Connector Seal & Body (2001-2019 6.6L Duramax)

Fitment

Built for 6.6L Duramax Chevrolet Silverado and GMC Sierra 2500HD and 3500/3500HD pickups from 2001 through 2019. That covers the LB7 (2001-2004), LLY (2004.5-2005), LBZ (2006-2007), LMM (2007.5-2010), LML (2011-2016) and L5P (2017-2019). Merchant lists this part through the 2019 model year only, so 2020 and newer L5P trucks are not covered by this listing. On any L5P truck, verify fitment by VIN, or send us the VIN and we'll check it for you. See the rest of our Duramax parts.

Why this part

Is your transmission leaking near the wire harness? With age, the seal at the pass-through connector can degrade and let fluid get into the connection. Fluid in there can cause erratic transmission operation and possible codes, and it can even force the transmission into limp mode.

That lines up with what's documented on these trucks. On the 2006-2007 LBZ, fluid wicking through the transmission's 20-pin connector is one of the electrical faults behind intermittent limp mode and a wrong gear display, along with harness damage and solenoid circuit codes like P0962. When the transmission limps, the computer commands maximum line pressure and locks it in third gear with P0700-series codes.

The 10686 is the one to pick when you want the whole joint renewed, not just the seal. You get the seal and the connector body together, so both pieces at the leak are new. Merchant calls it an easy-to-install fix if fluid is present in your connection.

What you get

• Pass-through transmission connector seal
• Pass-through connector body

Features:

• Direct Fit
• High-Quality Construction
• Durable Seal

Manufacturer warranty: 1 Year Limited.

About Merchant Automotive

Merchant Automotive has been making parts in Holland, Michigan since 2004. Its catalog centers on one platform, the 6.6L Duramax and the Allison transmission behind it. Most of what Merchant builds targets a known weak spot on these trucks instead of trying to cover every make on the road.

Frequently asked questions

Should I buy the 10686 or the 10685?

Both address a leak at the harness pass-through. The 10685 is the seal by itself. The 10686 is the seal plus a new connector body. If the old body is damaged, or you want everything at that joint new, get the 10686.

How do I know fluid is getting into the connector?

Look for a leak near the wire harness where it enters the transmission, then unplug the connector and check for fluid inside. Erratic shifting, transmission codes or limp mode alongside that leak point to the pass-through seal.

Is every limp-mode problem a leaking connector?

No. On 2001-2005 trucks, Class 2 serial-data faults from bad grounds, low cranking voltage or aftermarket radio interference can put the transmission in limp with no mechanical fault at all. Check the connector for fluid before you replace it.

Questions on fitment? Call the shop at the number in the header. We install everything we sell.