PCM

4L80e Transmission Conversion Harness

$250.00

SKU: P-120021

In Stock
In Stock
Ships by Aug 31
Free Shipping over $200
$100 Minimum Order
30 Days Return

Description

The PCM 4L80 conversion harness provides a streamlined, plug-and-play solution for swapping a 4L80e transmission into LS-based vehicles originally equipped with 4L60e, 4L65e, 4L70e, or 4L75e units. This specific version, P-120021, is engineered for 1997-2008 LS-based vehicles that utilize an external PRNDL switch, which is transferred from the original transmission. The design ensures that essential functions like cruise control and gear shift indicators operate as they did in stock form. While this harness simplifies installation by eliminating the need for segment swaps or complicated OS changes, basic tuning is required to adjust shift points for the new gear ratios and remove specific codes. Base startup tunes are available through the manufacturer for an additional fee, or users can apply a provided template via HP Tuners. Please note that this product is not for use in 5.7L Vortec trucks. Professional installation or tuning experience is recommended to ensure correct operation of the transmission control module.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandPCM
Part NumberP-120021
CategoryIgnitions and Electrical

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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