JohnPorter1090 Posted March 26 Share Posted March 26 Hey Yall, I have a 1984 f250 Diesel HD 4WD 4 Speed Manual. I was driving around the other day and noticed that my right brake light didn't work. The right turn signal does work. I tried changing the bulb but this didn't do anything. I tried a different bulb but I could only get it to work if I used an LED (I tested the incandescent bulb on the left side and it worked). Thinking it was fixed, I put it back together only to find that after driving a few miles the brake light stopped working again. A few miles after that it was working again. That night I took it offroading and the headlights randomly turned off for a few seconds. I checked my battery terminals, and fuses but didn't notice anything out of the ordinary. Anyone have an idea what might be causing this? P.S My truck does have LED headlights but I've had them for a while and I haven't noticed any electrical issues up until now. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 26 Share Posted March 26 I'd guess you have two separate problems. The tail light issue may be a ground problem as an LED takes a lot less current and might be able to light with a poor ground while an incandescent might not. The headlight problem is maybe a loose connection. You can see that the power feed on Page 17 and then Page 66 on the 85 EVTM here. Link to comment Share on other sites More sharing options...
viven44 Posted March 27 Share Posted March 27 Isn't the turn/stop lamp physically the same bulb ? If so and the bulb works well in the turn function, then the bulb itself and grounding aspects are fine. I think the problem likely resides in your turn signal switch which also controls the stop function Link to comment Share on other sites More sharing options...
JohnPorter1090 Posted March 27 Author Share Posted March 27 Isn't the turn/stop lamp physically the same bulb ? If so and the bulb works well in the turn function, then the bulb itself and grounding aspects are fine. I think the problem likely resides in your turn signal switch which also controls the stop function I was tinkering with the turn signal switch while holding down the brake, if the switch is slightly to one side then that side's brake light won't turn on. Looks like I'll just have to replace the switch, it's really worn out anyways. Thanks for the insight! Link to comment Share on other sites More sharing options...
JohnPorter1090 Posted March 27 Author Share Posted March 27 I'd guess you have two separate problems. The tail light issue may be a ground problem as an LED takes a lot less current and might be able to light with a poor ground while an incandescent might not. The headlight problem is maybe a loose connection. You can see that the power feed on Page 17 and then Page 66 on the 85 EVTM here. I'll go through the wiring and make sure everything is tight on the headlights. Thank you! Link to comment Share on other sites More sharing options...
viven44 Posted March 27 Share Posted March 27 I was tinkering with the turn signal switch while holding down the brake, if the switch is slightly to one side then that side's brake light won't turn on. Looks like I'll just have to replace the switch, it's really worn out anyways. Thanks for the insight! I've had good luck with the Shee-mar brand turn signal switches from Rockauto Link to comment Share on other sites More sharing options...
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