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Author Topic: Headlight swap question  (Read 11480 times)

Offline SUX2BU99

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Headlight swap question
« on: February 09, 2010, 12:22:23 pm »
As I'm doing my 90 grille swap, I noticed that my 85 low-beams have I believe 4 wires connected to them at the plug yet my 90 low beams have only 2. I am going to re-use my older wiring harness (I have an old-style glass-fuse block) and cut off the headlight pigtails from the 90 harness and splice them in. I figured I would just use my multi-meter and see which ones are positive and which are negative and connect them to the corresponding wires on my older harness but why does the older harness have more wires than the 90 one? Anything I need to know in advance before doing this?  Thanks.
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85 Chevy Silverado C10 short, wide, yellow, 2wd. Lowered, 60-over 350 with Dart Iron Eagle heads and Comp Cams XE268 cam, TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

Offline Irish_Alley

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Re: Headlight swap question
« Reply #1 on: February 10, 2010, 11:44:55 pm »
could it be ti have both high and low beams on with the high beam
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Offline SUX2BU99

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Re: Headlight swap question
« Reply #2 on: February 11, 2010, 08:32:03 am »
I know when I have my high beams on, the low beams also stay on. I don't know if the 89-91 are the same. My 85 low beams have 3 prongs on them but the 90 ones have only 2.
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85 Chevy Silverado C10 short, wide, yellow, 2wd. Lowered, 60-over 350 with Dart Iron Eagle heads and Comp Cams XE268 cam, TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

Offline VileZambonie

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Re: Headlight swap question
« Reply #3 on: February 11, 2010, 02:40:15 pm »
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Offline SUX2BU99

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Re: Headlight swap question
« Reply #4 on: February 11, 2010, 07:10:13 pm »
I did and I was hoping it would have said something about my question, but it doesn't. It only mentions two unused wires in the 90 harness and does not mention the 3 prong headlights vs. the newer 2 prong, which surprised me. Maybe I missed something.
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85 Chevy Silverado C10 short, wide, yellow, 2wd. Lowered, 60-over 350 with Dart Iron Eagle heads and Comp Cams XE268 cam, TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

Offline Irish_Alley

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Re: Headlight swap question
« Reply #5 on: February 12, 2010, 11:31:56 pm »
89-91 don't unless they been modded but thats why your 85 low had 3 prongs i believe so they stay on with the high do a volt test and see what they turn out to be
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Offline modular93fox

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Re: Headlight swap question
« Reply #6 on: February 13, 2010, 10:08:47 pm »
Just test the wires your current harness has for low beam and high beam and ground. Run those original wires to a seperate relay, and have the relay turn the headlights on/off. I would bet you a beer that your lights will be a shade brighter. Before I did the relay mod, if i turned on the radio, operated the blower motor or electric windows, the headlights would dim. gay. afterwards all good. If you dont know how to wire it up, just do a search on how to wire up relays...
clint
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Offline beastie_3

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Re: Headlight swap question
« Reply #7 on: February 14, 2010, 10:15:46 am »
Quote from: modular93fox on February 13, 2010, 10:08:47 pm
Just test the wires your current harness has for low beam and high beam and ground. Run those original wires to a seperate relay, and have the relay turn the headlights on/off. I would bet you a beer that your lights will be a shade brighter. Before I did the relay mod, if i turned on the radio, operated the blower motor or electric windows, the headlights would dim. gay. afterwards all good. If you dont know how to wire it up, just do a search on how to wire up relays...
clint

+1 for the relays. I installed a relay kit and there was an improvement.
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Offline VileZambonie

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Re: Headlight swap question
« Reply #8 on: February 14, 2010, 06:29:24 pm »
I'll be wiring up my 91 grille in my mutt in a few days if you want me to take pix
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Offline SUX2BU99

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Re: Headlight swap question
« Reply #9 on: February 15, 2010, 12:15:23 pm »
Sure, the more pics the better! Putting the lights on a relay is a good idea. Do the 91 low beams stay on when high beams are activated in stock form?
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85 Chevy Silverado C10 short, wide, yellow, 2wd. Lowered, 60-over 350 with Dart Iron Eagle heads and Comp Cams XE268 cam, TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

Offline Irish_Alley

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Re: Headlight swap question
« Reply #10 on: February 16, 2010, 03:40:59 am »
no only one at a time in stock form
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Offline SUX2BU99

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Re: Headlight swap question
« Reply #11 on: March 08, 2010, 04:36:30 pm »
Hey Vile, did you get those headlights wired up yet? I'm going to get power to my harness tonight I think and do some testing with the multi-meter. Probably a simple solution of either leaving one wire disconnected or tieing two together.
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85 Chevy Silverado C10 short, wide, yellow, 2wd. Lowered, 60-over 350 with Dart Iron Eagle heads and Comp Cams XE268 cam, TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

Offline VileZambonie

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Re: Headlight swap question
« Reply #12 on: March 08, 2010, 05:33:27 pm »
I already wired mine up and totally forgot to take pics and such for you! I'm sorry about that but I can tell you it was a piece of cake. Just follow the high and low beam and the schematic. If you are going to use the crystal lenses I would get the harness too before you bother soldering everything in.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10
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