Dan Crowley Posted March 16, 2021 Share Posted March 16, 2021 Thanks Dan, I spoke with Ron Francis wiring and they informed me the harness they sale is exact replacement of the original chassis harness, but because the harness is designed for gasoline engines, they are uncertain that their harness could be reconfigured for the idi engine setup. I’ve used the American Autowire update kit harness (which is a direct fit replacement) on a 78 f150 and is an excellent kit. So, I spoke with AAW and they said the same thing, that it was designed for gas engines only and had not heard of anyone adapting it for the idi Diesel engines. In my research, I did come across one individual who successfully adapted the AAW update kit to work with his 6.9l idi. I’m currently in the process of removing all of the truck’s wiring intact, except were it has been damaged. My plan is to purchase the $1500 update kit from AAW and reconfigure the engine setup for the glow plug relay and injection pump cut off. I will document everything and make it available so others will have access to this upgrade. Hi Danny, Good luck with the AAW kit. I still think it would be a good idea for you to order a Ron Francis catalog which is free, it has a lot of information on wiring with tips and do's and don't s. I found it very helpful to me and I need all the help I can get. Link to comment Share on other sites More sharing options...
Danny Campbell Posted March 21, 2021 Author Share Posted March 21, 2021 Having never worked on wiring on the older Diesels I can't say how much difference there is. I have determined that a lot of the gas engine variations were done with harnesses that plug into a pretty standard front harness. On your truck the front harness probably follows the same design as the gas engines in the fact that it runs from the right headlight area past the right side battery (only one on gas engines) back along the inner fender, through the firewall under the HVAC or heater case, across the dash and back out through the left side of the firewall and up to the left headlight. Because of the design replacing it is a real pain. Thought I would provide an update. I was able to successfully remove the chassis harness intact. I did separate the the connections than ran under the driver side frame rail to the back of the truck, leaving the complete wiring system in four sections (glow plug harness, charging and starter harness and the main chassis harness). Pictured on the ground is the chassis harness with the two branches that fed through each side of the firewall. The harness is in relatively good shape, with the exception of hackery at the brake switch, glow plug relay and radio. The charging harness was butchered up as seen in one the photos. Evidently the air conditioner was upgraded to r134 setup and the wiring for the compressor was juvenile. I was surprised by the lack of grounds for this harness, only chassis grounds and none to the frame. It’s no wonder I was having ground troubles. Now that the harness is out, I will start tackling other issues. I hope to began documenting the installation of the new wiring harness soon to this thread. It will include a complete harness replacement of the entire truck, 200 amp single wire alternator upgrade and a custom built fuse bock with a relay bank to run newer tech. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 21, 2021 Share Posted March 21, 2021 Thought I would provide an update. I was able to successfully remove the chassis harness intact. I did separate the the connections than ran under the driver side frame rail to the back of the truck, leaving the complete wiring system in four sections (glow plug harness, charging and starter harness and the main chassis harness). Pictured on the ground is the chassis harness with the two branches that fed through each side of the firewall. The harness is in relatively good shape, with the exception of hackery at the brake switch, glow plug relay and radio. The charging harness was butchered up as seen in one the photos. Evidently the air conditioner was upgraded to r134 setup and the wiring for the compressor was juvenile. I was surprised by the lack of grounds for this harness, only chassis grounds and none to the frame. It’s no wonder I was having ground troubles. Now that the harness is out, I will start tackling other issues. I hope to began documenting the installation of the new wiring harness soon to this thread. It will include a complete harness replacement of the entire truck, 200 amp single wire alternator upgrade and a custom built fuse bock with a relay bank to run newer tech. Well done! I'm following along as there's lots to learn. Link to comment Share on other sites More sharing options...
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