No left low beam

[Dennis Salzberg]

I have a 2000 GMC Sierra 1500 with no left headlight low beam. I have 13 volt to both wires. I am a 40 mechanic for class 8 vehicles.  Headlight switch or daytime running light relay or ? 

[Mikey52]

I have a 2000 GMC Sierra 1500 with no left headlight low beam. I have 13 volt to both wires. I am a 40 mechanic for class 8 vehicles.  Headlight switch or daytime running light relay or ? 

What type of light is it, if HID the ballast could be bad. I assume the continuity through bulb is ok?

[Jsdirt]

If you have voltage,  you're missing a ground.

[Doug_Scott]

I agree with Jsdirt.  There are three wires in that connector, connect either your voltmeter or your test light to the positive cable on the battery and check the third wire.  You should see battery volts or the light come on on the test light.  I used to check voltage using the ground wire on the connector when I ran into odd light issues,  it kills two possible problems in one test. 

[Dennis Salzberg]

This happened after the HD lights were installed. There are 2 wires at the plug. I agree on a bad ground, but where. I am back to original, factory lighting 9005 bulbs. Where is the exact location of the ground without tearing apart things.

 

[Jsdirt]

On my own vehicle with no wiring diagram, I would find the high beam & low beam - that leaves the ground. From there I'd cut it splice in my own ground - just saves a bunch of diag time.

 

What you could do for a test is grab a pin or sewing needle, stick it in the back of the headlight connector where the ground wire is, then run a jumper straight to battery ground - if the headlight lights, then cut/splice in a new wire, & just find an area with a good ground, crimp an eyelet on, and bolt it down. Probably would be easier to just bolt it where there's other easily accessible grounds, like the right front of the engine.

[Doug_Scott]

When you say HD lights, what do you mean?  Do you mean Xenon HID light kit?  If so, what changes did you make to install the kit?

[Dennis Salzberg]

Missing the ground is correct but I can not find it. Yes Xenon HD light kit. I know to run a ground wire but want to keep the truck original as possible

[Doug_Scott]

Go through the instructions for the hid kit and see where you connected to factory harness.. When you checked voltages at the plug was the bulb connected? If it was that explains getting battery voltage on both wires. 

The H4 HID kits I have installed came with a male plug that plugged into the factory headlight socket.  The only connections I had to make was one wire to battery and a couple of ground wires for ballasts. Is your HID kit similar? 

 

[Jsdirt]

I have one in our Grand Marquis. The kit had a control unit, which branched into 2 ballasts - one for each light. I had fused 12v power and a ground to the control unit - everything else hooked up to existing wiring.

 

I have since got rid of those crappy blue connectors - ran those for a year to make sure I wasn't going to have any problems. Waterproof connectors are the only way to go here. These blue things are just asking for trouble in the rust belt.

 

There's a wiring diagram on the control unit - not sure if you'll be able to see it clearly or not. Hopefully this helps.

 

 

 

 

[Doug_Scott]

That's the same as my kits were except I put one on my 2002 Yamaha FZ1 and the other on my Piaggio Fly 150 scooter.  Had to shorten the one head light harness because the FZ1 headlights are 5 inches apart, and the scooter only has one headlight. The control unit is a slick piece of work.  Without that you are looking at a couple of relays and on the H4 Bixenon you would have to find a way to trigger the solenoid in the bulb to get the high beam. 

 

Those scotchlok connectors come close to cutting the wires clean off.

[Jsdirt]

Yeah, they are junk (Scotchlok).

 

I still have a second HID kit with H4 bulbs - was going to use it in the RD350, but just upgrading to a regular H4 halogen was a HUGE improvement over the stock 35W regular incandescent. The OE headlight cast light exactly like a big candle, lol - orange compared to anything built after the '70's.

 

Maybe I'll use it on the Volvo, if the motivation strikes some day.

[Doug_Scott]

2 hours ago, Jsdirt said:

Yeah, they are junk (Scotchlok).

 

I still have a second HID kit with H4 bulbs - was going to use it in the RD350, but just upgrading to a regular H4 halogen was a HUGE improvement over the stock 35W regular incandescent. The OE headlight cast light exactly like a big candle, lol - orange compared to anything built after the '70's.

 

Maybe I'll use it on the Volvo, if the motivation strikes some day.

You will have to watch the connector on that new halogen bulb.  Those bulbs tend to pull more power, and the extra current can melt the connector pretty quickly.  I had a 87 fz750 that I bought new, put "arctic flare" halogen bulbs in it before heading out for a week long summer ride with a buddy. Pulled in to the motel in Lake Placid and turned the key off only to find the engine still running.  After some checking we found that running the bulb on highbeam those 100 watt bulbs melted a connector back in harness, shorting a few wires together.  Managed to remove the full fairing to get at the wiring harness using factory tool kits from my bike and my buddies 88 FJ1200. Promptly rewired headlights to use a relay after getting home. 

[Jsdirt]

I went with the 50/55W for that reason - I've seen lots of molten connectors and wiring from running 100w bulbs. They get REAL hot! Besides that, the 50/55w bulb is pushing the limits of the RD's charging system as it is. System was designed to run a 25/35 incandescent.  I don't think the system could charge the battery (or run the ignition with any reliability) with a 100w bulb in there. I've got it all wired up direct from the battery (fused) to a 5-prong cube relay - the original wiring controls the primary side of the relay, and the extra prong runs the low beam.

 

The whole charging system was rebuilt during the restoration, with the exception of the rotor - that's still the OE 45 year old winding. Only electronic part on that bike is the combined regulator/rectifier unit. Without that, I couldn't run the halogen. The updated regulator unit has adjustability as far as voltage output goes. I run an AGM battery, so it handles the abuse of low RPM riding for quite a while, along with the higher than normal voltage output I set the new unit to.