'87 Chevy R10 Headlight Issues

[hukinbull]

This may have already been addressed but I can't find it so Im gonna ask it. I have an '87 Chevy R10 with a 5.0 L 305. When the low beams are on, both work fine, however when I activate the high beams, only the right lowbeam stays on. The left one goes off. Shouldn't they both stay on? Any ideas where to start troubleshooting?

 

[89Suburban]

I moved your post into the exterior forum, that tech info forum was for write ups only.

Hopefully somebody here can steer you in the right direction with your question, welcome aboard.

 

[hukinbull]

I moved your post into the exterior forum, that tech info forum was for write ups only.

Hopefully somebody here can steer you in the right direction with your question, welcome aboard.

Ok thanks! Sorry for posting in the wrong spot. This is all new to me. Lol.

 

[89Suburban]

Ok thanks! Sorry for posting in the wrong spot. This is all new to me. Lol.

No sweat bro! We have a member here who has a ton of wiring diagrams in a photo album somewhere but I can not for the life of me find it or remember his name.

 

[89Suburban]

Here's the link to the wire diagrams.

http://www.gmsquarebody.com/forum/album.php?albumid=278

Eh, hard to read.

 

[hukinbull]

Here's the link to the wire diagrams.

http://www.gmsquarebody.com/forum/album.php?albumid=278

Eh, hard to read.

yeah it is a little hard to read. Hopefully someone has a clearer one or some other ideas....

 

[89Suburban]

My ****** Haynes book only shows single headlights.

I am thinking you may have a ground issue, just check them and clean them up and go from there. Check them at the bulb plug and where they bolt to the core support. I could be wrong, but I don;t think a bad dimmer switch can cause this as only one feed comes out for low beam, then splits to the 2 headlights.

 

[hukinbull]

My ****** Haynes book only shows single headlights.

I am thinking you may have a ground issue, just check them and clean them up and go from there. Check them at the bulb plug and where they bolt to the core support. I could be wrong, but I don;t think a bad dimmer switch can cause this as only one feed comes out for low beam, then splits to the 2 headlights.

Ok I'll start there. I'll let you know how it goes. Thanks!!

 

[J Knight]

This may have already been addressed but I can't find it so Im gonna ask it. I have an '87 Chevy R10 with a 5.0 L 305. When the low beams are on, both work fine, however when I activate the high beams, only the right lowbeam stays on. The left one goes off. Shouldn't they both stay on? Any ideas where to start troubleshooting?

Did you first check to see if you have power and ground to the left head light high/low beam plug end?

 

[RetroC10Sport]

Are you sure the high beam filament isn't burned out?

Those are low/high beam (three prong) bulbs as I recall.

 

[hukinbull]

Did you first check to see if you have power and ground to the left head light high/low beam plug end?

Yes I did and both are fine.

 

[J Knight]

Yes I did and both are fine.

Then its the headlight high/low with the high beam elament burnt out.

 

[hukinbull]

Are you sure the high beam filament isn't burned out?

Those are low/high beam (three prong) bulbs as I recall.

Its a 4 headlight system. The bright and dim are separate from each other. The dim works on dim, it just doesn't illuminate when the brights are activated.

 

[J Knight]

Its a 4 headlight system. The bright and dim are separate from each other. The dim works on dim, it just doesn't illuminate when the brights are activated.

Two of your headlights are LOW/HIGH beam and the other two are HIGH beams only. When you are in low beam the LOW/HIGH beams should be on. When you are in high beam the LOW/HIGH beams AND the HIGH beams should be on.

 

[hukinbull]

Two of your headlights are LOW/HIGH beam and the other two are HIGH beams only. When you are in low beam the LOW/HIGH beams should be on. When you are in high beam the LOW/HIGH beams AND the HIGH beams should be on.

ok. I did not know that. I will try replacing the light. Thank you for your help!!