80 series electrical problem

Joined
Mar 18, 2008
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7
blows all H/L bulbs (4) when brights turned on. testing shows 12v current on to low beams even when switch is off, has current (12V) on both leads to high beam bulb when switch is turned to bright or flash. I tested/replaced H/L relay, no effect. I tested continuity of dimmer & combi switches & show continuity across high & flash (dimmer) when switch is off. question... is the combi ? or dimmer? bad? dimmer piggybacks combi switch. have not removed either switch due to airbag & acsess difficulty. Dealer Tech says can't be switch. Also, fuses for H/Ls do not blow (15amp) . I hooked meter to battery & watched for volatage spike when switch is activated, H/Ls blew but voltage never changed & was @ 14.6 volts with engine idiling. problem came about suddenly.
 
Joined
Mar 19, 2008
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12
first of all do you have the auto headlight feature where the headlights turn on automatically when in the dark
I have electrical diagram for both types. Has continuity diagrams in it as well. dimmer has continuity all the time depending on whether high low or flash, easy to see on wiring diagram
 
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Joined
Mar 18, 2008
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7
ok, but why are both wires to each bright bulb hot...only needs one hot & why are lows hot with switch off? I'm using a pos Haynes manual...
 
Joined
Mar 19, 2008
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12
The headlamp lamps should not be live when switch is off. Only the control circuit which controls the headlamp relays switch the earth.
Check to see if your relays are on all the time, If they are then you have a fault in the control circuits(switch) if they are not on all the time you have a fault in the headlamp circuit. Is your switch a 4 position switch i.e off,tail,head,auto. Mine does all sorts of things like trun the headlights off when you turn the key off and open the door. I had a fault in the controller for the headlights and it did all sorts of funny things
 
Joined
Mar 18, 2008
Messages
7
electrical problem

I finally have time to get back to work on it today... I'll check the relay circuit 1st. I had actually tested/replaced the relay but failed to check the circuit itself. thanks for the advice! I'll post the outcome.
 

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