If you have a factory Gen 5 Truck (L83/L86) engine wiring harness and would like it to be converted (or reworked) into a simple to install standalone harness for your swap project, we offer what you're looking for. We go through the harness and remove everything you don't need, allowing for a quick and easy install for your project. All harnesses are tested upon completion on one of several engines in our shop with a GM Tech 2 Diagnostic Scan Tool to ensure 100% proper harness function. Hook-up wiring instructions are included with every rework.
We only need the engine harness and ECM (if reprogramming) to complete a rework. We do not need sensors, throttle pedals, battery cables, chassis harnesses, fuse boxes, etc., unless we have otherwise advised you per a conversation.
We leave the front O2 sensor wiring intact, as these are required for the engine to run properly, but remove the rear O2s and other emissions related wiring that is not necessary.
We do not change the appearance of your harness, or where the ECM is located on factory harness reworks. Please use the photo for reference of where the ECM is located (front left-hand side of the engine). If these things are of concern to you, we would be happy to make you a brand new standalone harness for your Gen 5 swap project to your specifications. Just give us a call!
Please use the "Additional Rework Info" box above to let us know which engine/trans and Year/Make/Model the harness you sent us came from and also the Year/Make/Model that you're swapping the engine into. Also, if we are reprogramming your ECM please use that text field to enter in your gear ratio and tire size for accurate speedo reading, as well as any major engine modifications, such as cam, headers, etc.
After completing checkout, please include a copy of the invoice that's emailed to you in the box you send your harness in. This is important and must be in the box!
Speartech Fuel Injection Systems
Attn: Harness Rework
3574 East State Road 236
Anderson, IN 46017
The shipping charge calculated during checkout is for return shipping back to you when we have completed your harness rework.
Keep A/C?: If you are running A/C or think that you might in the future, we can leave the air conditioning wiring in the harness. If not running A/C we will eliminate the wiring from the harness for a cleaner look. We recommend using a Vintage Air system on Gen 5 engines.
Additional Info: Please fill out any additional info necessary. Include which engine/trans and Year/Make/Model the harness you sent us came from and also the Year/Make/Model that you're swapping the engine into. If you're sending in a PCM/ECM for reprogramming, include any engine modifications (Cam, headers, etc.) as well as your gear ratio and tire size, if known. If gear ratio and/or tire size is not known, everything will still operate satisfactorily, but shift points and speedometer may be slightly off.