The Fleece Performance GM Automatic Transmission 20-Pin Pigtail is a replacement connector for the vehicle harness that plugs into the 20-pin connector on the Allison 1000 transmission in 2001-2019 6.6L Duramax trucks. When the original harness connector is cracked, has a broken latch, or has damaged terminals, the connection to the transmission can become unreliable. This pigtail lets you cut out the damaged connector and splice in a new one without replacing the whole harness. It replaces discontinued GM part number 12126459 and ACDelco PT729.
Key Features
- 20-pin connector for GM automatic transmissions, including the Allison 1000/2000
- 12" leads, each labeled with its pin position
- Includes 20 heat-sealable butt-style connectors
- Made in-house by Fleece Performance with automated wire cutting and terminal crimping
- Replaces discontinued GM 12126459 and ACDelco PT729
Benefits
- Repairs a damaged transmission harness connector without replacing the full harness
- Labeled leads make it easier to match each wire to the right circuit
- Heat-sealable splices help keep moisture out of the repair
- A replacement for a GM connector that has been discontinued
Installation Note
Disconnect the batteries before you start. Cut and splice one wire at a time, using the pin labels on the leads to match each circuit, and heat-seal every connector. If you find transmission fluid inside the connector, fix the leak at the pass-through connector seal on the transmission first. A new pigtail will not stop fluid from coming through the case.
Frequently Asked Questions
What does this replace?
It replaces the 20-pin connector on the truck's transmission wiring harness, GM part number 12126459 / ACDelco PT729, which has been discontinued.
How many do I need?
One. The transmission has a single 20-pin connector.
There's transmission fluid in my connector. Will this fix it?
No. Fluid in the connector usually comes from a leaking pass-through connector seal on the transmission case. Replace that seal, or the seal and connector body, first. Then replace the pigtail if the harness connector is also damaged.
Does it come with splice connectors?
Yes. It includes 20 heat-sealable butt-style connectors, one for each wire.
Does it fit other GM transmissions?
Fleece lists it for the Allison 1000/2000, 4L60E, 4L65E, 4L70E, 4L80E, 4L85E, 4T45E, 4T65E and 4T80E. Our vehicle fitment covers 2001-2019 6.6L Duramax trucks.
Fitment
- 2001-2019 Chevy Silverado and GMC Sierra 2500HD/3500HD with 6.6L Duramax (LB7, LLY, LBZ, LMM, LML, L5P) and Allison 1000 transmission
- Fleece application: Allison 1000/2000, 4L60E, 4L65E, 4L70E, 4L80E, 4L85E, 4T45E, 4T65E, 4T80E
Fixing a fluid leak at the transmission connector? See the Pass Through Connector Seal, Duramax Allison 1000 and the Allison 1000 Pass Through Connector Seal and Body.
What's Included
- (1) 20-pin transmission connector pigtail with 12" labeled leads
- (20) Heat-sealable butt-style connectors
For warranty information or to submit a claim, see our Warranty Form.
