JJM_Mack Posted October 14, 2022 Share Posted October 14, 2022 Hi, all! I'm restoring an Ultraliner and had to take the headlights out in order to replace both body panels behind them. When you take off the panels, the wiring harness in the panel has a connector behind it so you can disconnect the harness and leave it in the body panel. The headlights worked, except for being filled with water, before I started this. When I went to re-install the headlights, I: > Bought new Halogen Lamps (H4656 and H4651 - as specified), and tested them > Replaced the Headlight Sockets to the 4656 spec (not the H4 spec) > replaced the harness connectors between the truck and the body panel > tested the grounds, and checked all the wires in the panel harnesses with a Multi-meter and replaced some suspects > Also replaced the High-Beam Foot switch and the three connectors. All new connections are soldered. When I put the panels back in and plugged in the harnesses, I tested the sockets and everything worked fine - High Beam (Red), Low Beam (Yellow) power all came on when they should., and I'm getting 12V on each side. I plugged the Driver's side low beam in, and it worked fine in both high and low. I took that one out, and put the passenger side low beam in, and it worked fine in both high and low, BUT...... When I plug both low beam's in, the Driver's side works okay, but the power on the Passenger side immediately goes into High Beam (Red), and the High Beam Dash Light comes on, Pressing the High Beam switch will make the Driver side lamp switch, but it doesn't change anything on the Passenger side. When I plug all four lights in, both lights on the Passenger side come on in High, the Driver's side low beam comes on in low, and the Driver's side High Beam won't come on at all, plus the High Beam Switch only works the Driver side, plus the Trouble Buzzer screams at me until I unplug the High Beam Lamp on the Driver side. (I'm hearing that buzzer in my nightmares now) I checked the Headlight switch and the headlamp Relay and they and their wiring look fine. I tried swapping lamps, re-tested all the connections, and juggling the wires on the High Beam switch, and everywhere else I could reach, but no joy there either. I'm stumped! I can't go much further with my resto until I figure this one out. Bad Headlight Relay? Any ideas? TIA! > Joe Quote Link to comment Share on other sites More sharing options...
Solution Joey Mack Posted October 14, 2022 Solution Share Posted October 14, 2022 A ground not hooked up??? Quote Link to comment Share on other sites More sharing options...
JJM_Mack Posted October 14, 2022 Author Share Posted October 14, 2022 Checked all the grounds, but I'm thinking of running separate ones right from the sockets to ground to see if that helps. Thanks! 1 Quote Link to comment Share on other sites More sharing options...
JJM_Mack Posted October 16, 2022 Author Share Posted October 16, 2022 Ran all new grounds to each socket and that fixed it! Thanks! Joe 1 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted October 16, 2022 Share Posted October 16, 2022 Awesome !! I look forward to seeing pics of the truck as you go, and the finished project... jojo Quote Link to comment Share on other sites More sharing options...
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