I have a 1994 Chevy C1500, 4.3L V6 TBI. The truck has well over 250k on it and runs like a champ. I ran into a problem today when I realized my high beam was out on the driver’s side. So, I went to the parts shop and got a new sealed unit replacement assembly - figuring that the unit/bulb was bad. I replaced the headlight - both sides like a proper good boy. I still don’t have high beams. What could be causing this? I don’thave any blown fuses, and it doesn’t make sense that there’d be a seperate relay for each headlight. The only thing I can think of is that it’s the wiring - which tested with good voltage. I really don’t feel like rewiring my headlights. Can you think of any alternatives?
Where did you test the voltage? Did you test at the actual socket for the lamp on the driver side? Its a 3 wire , 1 ground, power to low, power to high filament. You might swap a relay if you have a similar type relay into the light relay socket otherwise try a new one. The volts can be there under noload but the system may not have enough amps due to bad contacts to light the filament. Test this by checking the high filament power wire by back probeing, with the voltmeter, the socket and turning on the light.
The problem might be in the DRL relay.
The passenger side high beam headlight is grounded directly to the body. The drivers side high beam headlight gets grounded through a contact in the DRL relay. If this relay doesn’t switch to ground the drivers side high beam headlight it won’t come on.
The relay is located in the engine compartment, at the front plenum panel.
Tester
Check the ground wire.
If you have power to the lights then there must be a ground problem. There should be a black wire running from the light to the fender well or a metal bracket close by.
Would a 94 have DRL? Just asking.
According to the wiring diagrams I checked from GM, this vehicle could have DRL’s.
Tester
UPDATE!!! - While driving this evening, I noticed it switched sides on me. Now I also always have a highbeam indicator on my dash. This leads me to believe that the problem is a short or bad ground in the indicator circuit - according to the diagram I saw it goes switch-indicator circuit-split to both lights. Does anyone with more experience have extra input? Is my assumption correct? Was I looking at the correct diagram? I’ll check it out tomorrow and post an update.
no DRL. at least none that I’ve seen
So now the passenger side is dead? Flash to pass uses the high beams does it work normally?
under any setting, the high beams only work on one side
Most of the time this kind trouble is due to a bad socket connection for the bulb. Check the connector contacts and see if they are burned or not making good connection to the bulb contacts.
Good news. we arrived at the same conclusion. I thru trial and error, and you thru expertise. Loose connections. How can I fix this?