nilknarf007 Posted March 27, 2020 Share Posted March 27, 2020 I have a 1985 F150 4x4 with the 4.9 i6. My smog delete didn't go very well, but thanks to some great advice from folks on the forum, she's running better than ever. I replaced the YFA carb with a YF, and installed an HEI distributor. Those two things solved all of my problems. But sometimes when you solve a problem, you create another. Now I have a ton of wires that don't hook to anything, they just run into the firewall. Any suggestions on what I should do with them? I was thinking of testing each one for switched power, and saving them for whatever may come up in the future. Also, the temp gauge hasn't worked since I bought the truck. However, I tested the sending unit and the gauge itself and both seem to be working. Should I just run new wire? Taking out the instrument cluster is a pain, so I want to have a plan for when I do it again. Here's a pic of the useless wires. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted March 27, 2020 Share Posted March 27, 2020 I could be wrong but I though the feed back system was a stand alone system? If so you should be able to follow the wires that went to the carb and maybe the dist. TFI unit back thru the firewall and pull it as a whole unit. Then you should be left with the main harness all trucks came with. Not this main harness did have some wires with plugs that were for other options your truck did not come with. My 81's were not a feed back but they were not top of the line options either, Custom & Ranger F100's. I used the Ranger harness in my truck because of the duel tank option. This was a different main harness not an add on like the AC would be. I think all harness had trailer relay power feed by the booster. Also by the radio area plugs for the radio (door speaker wires were a add on harness), clock and under dash light plugs are there. Again it is what I found from rebuilding my truck with a lot of help from the good people on here. Dave ---- Link to comment Share on other sites More sharing options...
85lebaront2 Posted March 27, 2020 Share Posted March 27, 2020 If they pass through an oval grommet in the firewall, 1985-86 trucks all seem to have the hole, but non-computer models have a plug there. If you, or someone else on here can find some of those in junkyards it would be a big help. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted March 27, 2020 Share Posted March 27, 2020 I could be wrong but I though the feed back system was a stand alone system? If so you should be able to follow the wires that went to the carb and maybe the dist. TFI unit back thru the firewall and pull it as a whole unit. Then you should be left with the main harness all trucks came with. Not this main harness did have some wires with plugs that were for other options your truck did not come with. My 81's were not a feed back but they were not top of the line options either, Custom & Ranger F100's. I used the Ranger harness in my truck because of the duel tank option. This was a different main harness not an add on like the AC would be. I think all harness had trailer relay power feed by the booster. Also by the radio area plugs for the radio (door speaker wires were a add on harness), clock and under dash light plugs are there. Again it is what I found from rebuilding my truck with a lot of help from the good people on here. Dave ---- BTW can you post a picture of the firewall on the other side of the booster kind of where the wires come out? We might be able to tell you the ones that can come out. Dave ---- Link to comment Share on other sites More sharing options...
85lebaront2 Posted March 28, 2020 Share Posted March 28, 2020 I could be wrong but I though the feed back system was a stand alone system? If so you should be able to follow the wires that went to the carb and maybe the dist. TFI unit back thru the firewall and pull it as a whole unit. Then you should be left with the main harness all trucks came with. Not this main harness did have some wires with plugs that were for other options your truck did not come with. My 81's were not a feed back but they were not top of the line options either, Custom & Ranger F100's. I used the Ranger harness in my truck because of the duel tank option. This was a different main harness not an add on like the AC would be. I think all harness had trailer relay power feed by the booster. Also by the radio area plugs for the radio (door speaker wires were a add on harness), clock and under dash light plugs are there. Again it is what I found from rebuilding my truck with a lot of help from the good people on here. Dave ---- The 1985/86 computer systems were essentially a stand alone system, they plugged into the front harness where the DS-II system would. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 28, 2020 Share Posted March 28, 2020 If they pass through an oval grommet in the firewall, 1985-86 trucks all seem to have the hole, but non-computer models have a plug there. If you, or someone else on here can find some of those in junkyards it would be a big help. This oval rubber cap is still available in the aftermarket, Bill. (or... it was, the last time I did a search for that p/n) And, yes that's an overlay harness. It can come out in its entirety. Link to comment Share on other sites More sharing options...
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