Lights and wires

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tsn98

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Jan 27, 2016
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Location
Connecticut
First Name
Tom
Truck Year
1988
Truck Model
K5
Engine Size
350
So last night I was finishing buttoning up some stuff on the interior of my 88 K5 Blazer, I just installed an aftermarket radio and speakers as well as some custom interior panels, and I turned on my lights, and my dash lights didn't come on, and my headlights are being funky, all 4 are always on (it's got an 89 grille and light setup on it) but they're on super dim, and on the driver's side when you switch from low to hi beams, the both stay on but whichever one is selected gets bright, but both are always on. The passenger side, both just stay dimly lit no matter is hi or lo beams are selected. I checked the fuses and they're all good... tried everything I could think of... Also when putting in the radio I found an orange and a brown wire that come up behind the radio, the orange having constant power and the brown having power only when the lights are turned on. Not sure if they're related to the dash/headlights problem or something else entirely. Anyone have any ideas?

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chengny

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Feb 22, 2012
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Location
NH
First Name
Jerry
Truck Year
1986
Truck Model
K3500
Engine Size
350/5.7
So last night I was finishing buttoning up some stuff on the interior of my 88 K5 Blazer, I just installed an aftermarket radio and speakers as well as some custom interior panels, and I turned on my lights, and my dash lights didn't come on, and my headlights are being funky, all 4 are always on (it's got an 89 grille and light setup on it) but they're on super dim, and on the driver's side when you switch from low to hi beams, the both stay on but whichever one is selected gets bright, but both are always on. The passenger side, both just stay dimly lit no matter is hi or lo beams are selected. I checked the fuses and they're all good... tried everything I could think of... Also when putting in the radio I found an orange and a brown wire that come up behind the radio, the orange having constant power and the brown having power only when the lights are turned on. Not sure if they're related to the dash/headlights problem or something else entirely. Anyone have any ideas?

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I'm fairly certain that (without some modifications) the H/L design of the wiring used in your 88 isn't compatible with the V22 RPO option (quad headlights) installed in the 89 grille/HL setup. Prior to 1989 the V22 option had one dual filament sealed beam and one single filament sealed beam. This was how they looked:

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And this is the wiring diagram for the 88 and down circuit - note the three pin connectors used for the HI/LO headlights:

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Here is the wiring for the 89 and up V22 option - both sealed beams were wired with a two pin connector:

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So, the later models did not have the two headlights on at the same time.

As for the radio wiring: is it possible that the colors are not orange & brown but rather yellow & gray?

If that is the case, the yellow is ignition switched power and the gray is spliced into the instrument lighting circuit and is backlighting (you don't need it with modern head units)
 

tsn98

Junior Member
Joined
Jan 27, 2016
Posts
24
Reaction score
1
Location
Connecticut
First Name
Tom
Truck Year
1988
Truck Model
K5
Engine Size
350
I'm fairly certain that (without some modifications) the H/L design of the wiring used in your 88 isn't compatible with the V22 RPO option (quad headlights) installed in the 89 grille/HL setup. Prior to 1989 the V22 option had one dual filament sealed beam and one single filament sealed beam. This was how they looked:

You must be registered for see images attach


You must be registered for see images attach


And this is the wiring diagram for the 88 and down circuit - note the three pin connectors used for the HI/LO headlights:

You must be registered for see images attach


Here is the wiring for the 89 and up V22 option - both sealed beams were wired with a two pin connector:

You must be registered for see images attach


So, the later models did not have the two headlights on at the same time.

As for the radio wiring: is it possible that the colors are not orange & brown but rather yellow & gray?

If that is the case, the yellow is ignition switched power and the gray is spliced into the instrument lighting circuit and is backlighting (you don't need it with modern head units)
Thanks for all the info! There has definitely been significant modifications to the wiring and a whole new radiator support etc put in to convert the headlights by the previous owner. He appeared to leave ALL the wiring for the old headlights still attached and spliced the new ones in so the wiring up in front is an absolute mess.
There is definitely an orange and brown wire coming up behind the dash that has a connector on it but isn't connected anything, but there is the yellow and gray like you said that go into the radio, I removed the grey illumination wire like you said and bam! The headlights are back to normal! Dash lights still aren't on... But it's progress for sure.
Checked the fuse for the dash lights and that's still good... Any ideas on those or on the two mystery wires???
Thanks for the help!

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