How to rebuild and install a wiring harness for either fuel injectors of ignition coils

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dtennes

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This thread is an education in how to rebuild complete wire harnesses for complete KJ fuel injector and ignition coil circuits.

In hindsight, this was actually a very simple effort after subtracting out a lot of trial and error. What follows is the streamlined "How To" broken out into 8 sections.

Contents
0. Various observations and warnings (especially for novices like me) regarding strategy, tactics, risks, planning.
1. The appropriate Service Manual (for your specific vehicle) content regarding circuits, routing,
2. The necessary physical components that you will need to identify (examples are for 2003 KJ 3.7L)
3. Tools that you will need
4. Where to buy components and tools
5. How to lay out your bare wires
6. Splicing and splice insulation
6. How to correctly attach terminals to wires, set those terminals into sealed connectors, test conductivity
7. Installing new harness(es) temporarily to test for effectiveness, then do the final permanent splice-in
 

dtennes

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Joined
Sep 4, 2022
Messages
93
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This thread is an education in how to rebuild complete wire harnesses for complete KJ fuel injector and ignition coil circuits.

In hindsight, this was actually a very simple effort after subtracting out a lot of trial and error. What follows is the streamlined "How To" broken out into 8 sections.

Contents
0. Various observations and warnings (especially for novices like me) regarding strategy, tactics, risks, planning.
1. The appropriate Service Manual (for your specific vehicle) content regarding circuits, routing,
2. The necessary physical components that you will need to identify (examples are for 2003 KJ 3.7L)
3. Tools that you will need
4. Where to buy components and tools
5. How to lay out your bare wires
6. Splicing and splice insulation
6. How to correctly attach terminals to wires, set those terminals into sealed connectors, test conductivity
7. Installing new harness(es) temporarily to test for effectiveness, then do the final permanent splice-in
This is a work in progress and content will accumulate over the next few days...
 

dtennes

Full Access Member
Joined
Sep 4, 2022
Messages
93
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This thread is an education in how to rebuild complete wire harnesses for complete KJ fuel injector and ignition coil circuits.

In hindsight, this was actually a very simple effort after subtracting out a lot of trial and error. What follows is the streamlined "How To" broken out into 8 sections.

Contents
0. Various observations and warnings (especially for novices like me) regarding strategy, tactics, risks, planning.
1. The appropriate Service Manual (for your specific vehicle) content regarding circuits, routing,
2. The necessary physical components that you will need to identify (examples are for 2003 KJ 3.7L)
3. Tools that you will need (with recommendations)
4. Where to buy components and tools
5. Explicit, required part numbers for building connectors from scratch.

6. Suggestions for layout
7. Splicing and splice insulation suggestions
8. Links to YT "How to's"
9. Installing new harness(es) temporarily, test for effectiveness, then do the final permanent splice-in
10. Illustrations where helpful

I am attaching a ".pdf" file that outlines everything with some illustrative images.

>>>NOTE<<<
The content explicitly applies to the 3.7L KJ PowerTech V6 engines in a 2003 Liberty. There may be direct applicability for 2002 and 2004, and possibly 2005 and 2006, but no promises. Also possible applicability for other vehicles using this engine (example Ram 1500, Durango, check the list on Wikipedia).

This is the final draft. Anyone that stumbles across this and has any input whatsoever is very welcome.
 

Attachments

  • harness_instructions_20231108_0913.pdf
    3.5 MB · Views: 13
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dtennes

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Messages
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Final draft
 

Attachments

  • harness_instructions_20231108_0913.pdf
    3.5 MB · Views: 14
Last edited:

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