No Headlights

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Michael 247, Jan 23, 2020.

  1. Michael 247

    Michael 247 Light Load Member

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    1990 Volvo / White / GMC..Both Headlights blinked off a few times over a 2 day period..This mourning both not working at all..anybody know where the relay is ??
     
  2. Powder Joints

    Powder Joints Subjective Prognosticator

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    Should be near or in the fuse box I think.
     
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  3. BoxCarKidd

    BoxCarKidd Road Train Member

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    By 90 were they not in the flip down panel under the center of the dash? Before that they were behind the panel on the left side of the clutch pedal?
     
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  4. Michael 247

    Michael 247 Light Load Member

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    Found it by the clutch...Had Dirt built up behind the Relay..Horn Relay is beside it so I changed them and got Headlights Working..
     
  5. Michael 247

    Michael 247 Light Load Member

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    Headlights out again..Swaped 2 different relays but still no Headlights
     
  6. 062

    062 Road Train Member

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    Have you checked for 12v at the headlight. Does it have fuses or breakers?
     
  7. Mike250rs

    Mike250rs Medium Load Member

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    Check for connectors that go from hood to frame. Those go to crap on every truck after a while
     
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  8. BoxCarKidd

    BoxCarKidd Road Train Member

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    Is that is a push in breaker look closely and the connection terminals. They sometimes overheat and cause a bad connection. If the breaker was shorting out it may have damaged the breaker. Replace it and check its connections.
     
  9. Michael 247

    Michael 247 Light Load Member

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    I swapped the Breakers..The connection plug near Headlight has power to all 3 wires..when I unplug connectors on both sides they have power to middle wire only..
     
  10. BoxCarKidd

    BoxCarKidd Road Train Member

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    Sounds like bad ground to headlights. Which wire is hot should change on bright and dim. The other is ground.
     
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