This IS the classic symptom of a broken ground circuit. A fast way to verify this is to unplug the left headlamp bulb. If the right side has a bad ground, that bulb will go out completely.
When using a jumper wire, as you likely did, to check the ground circuit, the problems I've made are: 1, the clip lead doesn't make a good connection to the bumper or bolt head under the hood, and 2, I put the other end of the jumper wire into the back side of the bulb's connector. That only bypasses the ground wire, not the connection between the socket terminal and the bulb's terminal. Instead, touch the jumper wire right to a slightly exposed part of the bulb's terminal. For the ground side, I've had the worst luck using the frame as they're coated with paint, rust, rustproofing, or dirt. The best places for me have been the battery's negative cable, and any silver screw heads bolted to metal braces under the dash.
Another way to verify a bad ground is to measure the voltages on all the bulb's terminals. Here again, this should be done on the bulb, not by back-probing alongside the wires in the socket. If you find some voltage on all the terminals, none of them are grounded.
Often wiggling the connector will make the headlight flash bright intermittently. Depending on the bulb style used in your van, it's not unheard of for a terminal to break loose from the bulb. Those can usually be removed and resoldered to the bulb.
Both headlight bulbs' ground wires are spliced together, then a single wire goes to ground. That final ground is not a suspect, as in rusted off at that terminal, because that would cause the left side to be dim or off too. Unless the right side ground wire was chewed off by a mouse or damaged some other way, it's much more likely the cause of this problem is right at the connector for the right bulb.
Let me know what you find and with what type of test.
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Thursday, December 11th, 2025 AT 1:32 PM
