Repair Summary: Replacing HID Headlight Electronic Ballast

Discussion in 'Gen 2 Prius Main Forum' started by jimolson, Aug 5, 2021.

  1. jimolson

    jimolson Member

    May 1, 2006
    Indianapolis, USA
    2009 Prius
    Earlier this week I posted a bitchy message to this forum talking about the failure of my HID headlight electronic ballast caused by the headlight assembly leaking water. All of this water in the headlight accumulates in the ballast, the lowest part of the headlight assembly.

    I poured nearly 0.5 liters of water out of my cracked headlight assembly.

    I replaced my dead ballast with a Dorman p/n 601-057 replacement ballast. Purchase price was approximately $115. The outward appearance of the Dorman ballast is that it is an exact copy of the Toyota factory ballast.

    However, this means that Dorman's lamp (="bulb") plug is the same fat sucker that Toyota uses that will not thread through the headlight housing.

    This importance of this observation will become clear in about 6 paragraphs: Dorman's lamp plug is made by the same vendor that Toyota used. Parts from Toy's lamp plug can be swapped interchangeably with Dorman's plug.

    Cut the lamp plug off of the failed Toyota ballast. At this point you can trash the rest of the ballast except for the two conductor DC power harness that pulls out of the socket in the ballast.

    Then gently pry open the Toyota lamp plug starting with removing the aluminum RF shield. The shield is held on by two bent tabs.

    Then disassemble Toyota's plastic lamp plug by releasing its 3 snap-o-matic clasps. (The third clasp is located in the neck where the harness enters the plug.) Tug on both silicone wires with needle-nosed pliers and note that the contacts crimped onto these wires will withdraw easily from the plastic plug assembly.

    Save the following items from the Toyota plug disassembly: (1.) outer plastic protective shell, and (2) inner plastic part that still encloses the twin contacts that touch the lamp's terminals.

    Now disassemble Dorman's identical lamp plug and notice that releasing its 3 snap-o-matic clasps are not sufficient to free up the outer shell. The reason is that Dorman filled the inside of its plug assembly with silicone potting compound. I had to break up Dorman's outer shell with the pliers and discard it.

    Then peel away Dorman's silicone potting compound with tweezers and withdraw the twin crimped contacts from the inner portion of the plug assembly. Note that these are exactly the same crimped terminals that Toyota used. Discard the inner portion of Dorman's plug assembly.

    Now that the new Dorman lamp-bound wire harness has been reduced in size by removal of its giant plug, thread the harness through the headlight assembly. Then reinstall the lamp plug, but use the plug you harvested from the Toyota ballast.

    You're done.

    It would have been helpful if Dorman had not backfilled its lamp plug with silicone. Better yet, Dorman might have simply left the plug off the lamp harness and shipped it in the carton in a plastic bag. That Dorman didn't do this suggests that their ballast must serve a number of Toyota headlight part numbers and most them allow the fat plug to pass through them.
    SFO likes this.