81f100custom Posted April 27, 2018 Share Posted April 27, 2018 This is on a 81 F100 with the SROD transmission. I have checked the switch for proper operation in and out of the truck and it works as it should. When it is screwed into the plate it goes in which is indexed the lights now stay on all the time. This just started about a week or so ago. Before that they where working as they should in reverse only. I am just not sure what is going on in the part the switch screws into that is now keeping them on all the time. I have not taken this plate out yet like showing in the pic. Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 27, 2018 Share Posted April 27, 2018 The circuit is shown on Page 46 here: Electrical/EVTM/1981 EVTM/Lights. You pretty obviously have power to the switch on the pink/orange hash wire, but you should check. And you apparently always have power out on the black/pink wire. But if you go to Page 48 you'll see that it says to check the adjustment of the switch if the backup lights stay on. Link to comment Share on other sites More sharing options...
81f100custom Posted April 27, 2018 Author Share Posted April 27, 2018 As far as I know there is no adjustment. If you loosen it any at all then it will not be tight and would just vibrate out. All it does is simply screw in and out. It is either tight or loose. Link to comment Share on other sites More sharing options...
1986F150Six Posted April 27, 2018 Share Posted April 27, 2018 As far as I know there is no adjustment. If you loosen it any at all then it will not be tight and would just vibrate out. All it does is simply screw in and out. It is either tight or loose. Could a locknut be used? Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 27, 2018 Share Posted April 27, 2018 As far as I know there is no adjustment. If you loosen it any at all then it will not be tight and would just vibrate out. All it does is simply screw in and out. It is either tight or loose. There's no lock nut on it? Usually those have a nut on the neck that you tighten down when you get it adjusted correctly. I'll look later today to see if I have the adjustment procedure in the shop manual. Link to comment Share on other sites More sharing options...
81f100custom Posted April 27, 2018 Author Share Posted April 27, 2018 There's no lock nut on it? Usually those have a nut on the neck that you tighten down when you get it adjusted correctly. I'll look later today to see if I have the adjustment procedure in the shop manual. The pic above is from the shop manual I have. I have see nothing referring to a locknut. It has worked just fine since about 1990 just the way it is. I was just thinking maybe something in the trans itself has changed or become worn maybe. The pic above looks identical to what I have plate, snap ring and switch. Link to comment Share on other sites More sharing options...
1986F150Six Posted April 27, 2018 Share Posted April 27, 2018 The pic above is from the shop manual I have. I have see nothing referring to a locknut. It has worked just fine since about 1990 just the way it is. I was just thinking maybe something in the trans itself has changed or become worn maybe. The pic above looks identical to what I have plate, snap ring and switch. Have you tried taking the switch out and connecting it to the wiring to see if the lights are on? If so, the switch is bad. Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 27, 2018 Share Posted April 27, 2018 Have you tried taking the switch out and connecting it to the wiring to see if the lights are on? If so, the switch is bad. The 1981 shop manual says the backup light switch is not adjustable. The catalog says that the switch is part # D8BZ 15520-A, is Motorcraft part SW-1486, and carries ID #D8BR 15520-AA on it. Link to comment Share on other sites More sharing options...
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