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Headlights and Cruise not working

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by wilsonsk, Sep 29, 2015.

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  1. wilsonsk

    wilsonsk Junior Member

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    Headlights are working, I ran a jumper from the ground prong on the bulb to a body bolt and plugged the plug onto the bulb as well, there is enough prong to get the alligator clip and slide the plug on most of the way. I did this on one side and it fixed both, so somewhere after the left and right harnesses combine (at least the ground) the ground is compromised.

    Now for the kicker, the cruise started working again as well! I guess my assumption here would be that there is a shared body ground or multi pin connector that covers multiple circuits is bad. The car has been in two accidents, one on each front corner, so it has definitely been worked on.

    My short term plan moving forward is to splice into the ground at both headlight plugs and make a connection going both to the bulbs and the harness and connect them to the body. This appears to back feed and create a ground for a least a portion of the cruise control system. I realize this is not really an elegant nor thorough repair, but I will need to start tracing wires to see if I can find the breech in the ground continuity, so this will have to suffice for now.

    Thoughts?
     
    #21 wilsonsk, Sep 30, 2015
  2. epoch_time

    epoch_time Active Member

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    Interesting Wilson and good work!!

    I have seen a number of chevorlets that run headlight ground from passenger side headlights to driverside grounding area (or visa-versa) and never understood why... Sounds like toyota does something similar and to tie multipul (cruse ctl) grounds into one ground lug is not a good idea imho..

    I had added an additonal ground to the prius ice years ago..It got rid of am radio static when driving over manhole covers... (not related to your situation) You cant get enough grounds in a prius..

    Finding a good easy access ground will require I little thought. I will get back to you..let me look at the prints grounding techniques..

    I did follow the grounds from headlights yesterday one headlight ground was labeled EA The other headlight called its Ground EB this same headlight showed an additional ground called EC but with notation of rhd (right hand drive where steering colume is on the right side of car)
    european model...
    Even though those grounds were labled differently I had a sneeky feeling one of the headlight grounds would be going to the opposite side of the car..(not sure if you indicated this, but wouldn't supprise me at all)

    I will study the prius grounding philosphy and try to understand it.. looking at cruse control schematics only showed engine ecu side of CC . I never found CC control switch/button. You may have weak engine ecu ground.

    Off to look at schematics..
     
    #22 epoch_time, Sep 30, 2015
  3. wilsonsk

    wilsonsk Junior Member

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    Thanks a lot for all of the help! I'll go ahead and add an ICE to body ground just to be safe in addition to grounding the lights.
     
    #23 wilsonsk, Sep 30, 2015
  4. epoch_time

    epoch_time Active Member

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    Hey Wilson
    I got some good info ..

    left headlight ground is called EE bolted to divers side strut colume (see below for more exact location) just at the left upper edge of the fuse block/relay/pannel where relays h-lp and dim are housed..

    right headlight ground is called EB is shown at passenger upper inside fender just a foot or so forward of hood hinge (more detail below)...

    Ground connection EA (right hand drive models) is right next to EB and errelivent..

    The underhood diagram looks almost hand drawn like all pictures in prius service manual I will look at these grounds in my genII prius
    to see if there any identifiable lables/marks/ect ...

    Back in a few..

    My prius has white with black stripe wires attached at locations EB and EA just between passenger upper fender and window washer fluid reservoir..

    There are two ground locations on the drivers side strut housing colume The lower one pointing a little more toward the engine has the white with blk strip wires on it (EE) the one closer to fuse pannel has black wires (EF provides mg1 & 2 control signal shielding ground)..

    The schematic ground wires for all devices seem to use the same color code white/black stripe for grounds...should be same color wire at headlight socket ...

    A good time to torque all visable ground connections..
    Let me know if this fixes everything...

    I just checked EB EA connections on my prius they are solid..

    My prius shematics are for 2004 model.. there could be slight varaitions over the years and I have found errors...Funny that grounding one headlight fixed both when schematic shows different grounding locations for each headlight they must also be an interconnection ground between headlights?

    I will be amazed if this is it...I cant immagine both grounding locations to be loose?
     
    #24 epoch_time, Sep 30, 2015
    Last edited: Sep 30, 2015
  5. wilsonsk

    wilsonsk Junior Member

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    You wouldn't want to snap some pics of your grounding points would you? I'm assuming the harness shares a ground, and there are redundant local grounds as well, I suspect in the two repairs (one on each side) not everything got grounded like it should have.

    Thanks!
     
    #25 wilsonsk, Sep 30, 2015
  6. epoch_time

    epoch_time Active Member

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    let me try and attach pdf file showing ground locations. Hard to find the right pdf... I will look for headlight pdf next...
     

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    • 74.pdf
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    #26 epoch_time, Oct 1, 2015
    Last edited: Oct 1, 2015
  7. epoch_time

    epoch_time Active Member

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    Hi wilson I'm attaching headlight diagram. I should have done this two day ago..It easier than I thought it would be..
     

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    #27 epoch_time, Oct 1, 2015
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