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LMC Truck



Username Post: Headlights auto dim-1996 GMC Jimmy        (Topic#347222)
AMAFLYBOY 
Forum Newbie
Posts: 14

Reg: 10-23-12
09-19-17 01:09 PM - Post#2708156    

I was on a long road trip last week and noticed after dark that with the head lights on I could hardly see the road.(it was nice when other drivers were next to me to light up the world)I thought I would run with the high beams on and they might help, which they did... for a little while. However after about 15-20 minutes again I was struggling to see the road. Then I tried the low beams and they were brighter than the high beams... for a little while. I ended up switching between high and low beams every 15-20 minutes or so.
This seems weird and I'm not sure where to start? Is it a bulb issue? Or is it something in the wiring? The Battery is a new (as of feb)one. The Volt meter on the dash is showing ~13.5V.



 
LMC Trucks
SleeperSS 
Senior Member
Posts: 2537
SleeperSS
Loc: Spanaway, Wa
Reg: 10-17-04
09-19-17 02:13 PM - Post#2708163    
    In response to AMAFLYBOY

Are they composites or seaside beam? S10/Jimmy sealed beams are marginal at best. First thing I would do is clean up the grounds on the core support...at 21 years old they might need a little help. If that fixes your problem, you can move on to make them work better. If you have sealed beams, consider upgrading to composites. It will require a grill change and wiring changes, but it's worth it. Next on the hit list is upgrading the wiring itself and using relays to boost the voltage at the plugs to battery voltage.
if you check them now, you'll be lucky to get 11.5v. After the upgrade you'll be getting 13.5t-14v...night into day.

Something else you might look at is the headlight switch. After your lights have been on and the switch warms, try gently rocking the switch up/down. Corrosion builds up inside the switch and causes the lights to flicker. I had that problem and a new switch fixed it....didn't help the crappy light output...but changing to composites with SilverStar bulbs worked great. I still have to do the wiring upgrade...

U.S.C.G. "So others may live"

'96 S-10 SS
'02 BlaZeR2





 
AMAFLYBOY 
Forum Newbie
Posts: 14

Reg: 10-23-12
09-19-17 05:58 PM - Post#2708185    
    In response to SleeperSS

They aren't the sealed beams, they just have the replaceable bulb in the back of "plastic" fixture. I have been looking at new LED fixtures with projectors and fog lights but they don't make those for the jimmy but all kinds for the Blazer. I didn't want to go to all that trouble if it is a wiring issue. I will check the switch tomorrow.




 
SleeperSS 
Senior Member
Posts: 2537
SleeperSS
Loc: Spanaway, Wa
Reg: 10-17-04
09-19-17 07:03 PM - Post#2708198    
    In response to AMAFLYBOY

Since they are already composites, I'd do the wiring upgrade after checking the switch.

U.S.C.G. "So others may live"

'96 S-10 SS
'02 BlaZeR2





 
AMAFLYBOY 
Forum Newbie
Posts: 14

Reg: 10-23-12
09-20-17 08:38 AM - Post#2708229    
    In response to SleeperSS

I just checked the Voltage at the lights and have 12.4v



 
SleeperSS 
Senior Member
Posts: 2537
SleeperSS
Loc: Spanaway, Wa
Reg: 10-17-04
09-20-17 10:54 AM - Post#2708243    
    In response to AMAFLYBOY

If you decide to do the wire/relay upgrade, you'll be amazed at the difference in light output.

U.S.C.G. "So others may live"

'96 S-10 SS
'02 BlaZeR2





 
raycow 
Honored Member
Posts: 27096
raycow
Loc: San Francisco, CA
Reg: 11-26-02
09-20-17 10:57 AM - Post#2708244    
    In response to AMAFLYBOY

If that 12.4V is with the engine running, you definitely have a resistance problem. Your choices are to troubleshoot ALL the wiring and connectors between the headlight switch and the lamps or to install relays. IMO, relays will be a lot faster and easier.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
AMAFLYBOY 
Forum Newbie
Posts: 14

Reg: 10-23-12
09-20-17 11:13 AM - Post#2708246    
    In response to raycow

my wife took it to town on her grocery run this am and i had her drive home with the lights on and leave it running. I then checked the Voltage and had 11.3v at the lights. 13.4v at the switch and 13.6 at the Alternator. I have not yet checked the voltage downstream of the switch, but looking at the wiring diagram it would make sense that it is the high/low beam switch that may be the issue. That looks to be expensive and a pain to replace. which relay kits do you recommend?



Edited by AMAFLYBOY on 09-20-17 11:14 AM. Reason for edit: No reason given.

 
raycow 
Honored Member
Posts: 27096
raycow
Loc: San Francisco, CA
Reg: 11-26-02
09-20-17 12:00 PM - Post#2708254    
    In response to AMAFLYBOY

If you suspect the dimmer switch, troubleshooting is usually less expensive than replacing. Parts vendors just LOVE customers who don't troubleshoot before buying.

Unplug the wire connector at the dimmer switch and use your multimeter to find out which contact is hot when the headlight switch is turned on. Use a short piece of wire to jump the hot contact to each of the other contacts, one at a time. With the jumper connected, go back to the lights and measure the voltage again.

As for the relays, I have never used a kit. I just buy loose relays, connectors, and wire and assemble it myself. If you feel more comfortable using a kit, I wouldn't expect any of them to be "bad", but it might be a good idea to inquire about the vendor's return policy before you lay down your money. It would also be nice to know what wire gauge was used, but most vendors likely won't have this info unless they can speak Chinese.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
SleeperSS 
Senior Member
Posts: 2537
SleeperSS
Loc: Spanaway, Wa
Reg: 10-17-04
09-20-17 12:03 PM - Post#2708256    
    In response to raycow

With the human hair sized wires they used, voltage will always be sub par...

U.S.C.G. "So others may live"

'96 S-10 SS
'02 BlaZeR2





 
AMAFLYBOY 
Forum Newbie
Posts: 14

Reg: 10-23-12
09-20-17 12:18 PM - Post#2708259    
    In response to raycow

I suspect the Dimmer switch because when I switch from high to low or low to high the New one is always brighter for about 15 mins... on the wiring diagram in the haynes manual nothing changes until the dimmer switch. so any problem with the main switch would be unaffected by the dimmer selection. so I think I will just use the existing system to trigger the relays and run 14AWG straight from the battery to the Lights with a 10AMP fuse and a good relay. I am not sure I want to try to trace wire all through the depths of the vehicle. that dimmer is expensive.
what suggestions do you have for good relays?




 
raycow 
Honored Member
Posts: 27096
raycow
Loc: San Francisco, CA
Reg: 11-26-02
09-20-17 01:09 PM - Post#2708265    
    In response to AMAFLYBOY

I have been buying from Allied since I was kid. In other words, they go back a long way. Of course when I was a kid the parts weren't made in China, but to this day I have never received a bad anything from them.

https://www.alliedelec.com/te-connectivity-14327 72...

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
LMC Trucks
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