90 vette headlight trouble

Sounds like you have a couple problems.. Opening & Brightness.

This will get your headlights opening and closing properly.

On the brightness.... maybe check the connectors when doing the bushing repair.

keithdesselle wrote:

Thanks Ric. I'll check it out more, but as far as I can tell all of the wires are plugged in well and no smashed sections. I'm thinking that both problems are from the same spot for some reason, they both started at the same time.

Sorry this is long but I've tried to cover the waterfront here.

Ric is right on the probability that the bushings in the motor gearbox are shot. The website Ric referenced is great. Go slowly in loosening the screws between the motor and the gearbox (so that you can tip the motor and release pressure between the worm gear and the teeth on the big nylon gear). Scrape off the black paint around the screw heads and leave a drop of penetrating oil on each screw overnight -- saves shearing the screws -- which would get you into another fussy repair. (Post here if that happens and we can offer tips.)

Elecrical symptoms point to a ground problem between the ground terminal on the left headlamp and its chassis connection. Following is based on pages 100 and 102 from the '89 shop manual -- '90 should be similar however there was a change in the harness connector between the frame harness and the actual headlight units (I think this was to support the higher wattage lamps that went into the '90).

There are separate grounds for the right and left headlights; however, there's a tie wire between the two grounds. The broken or poor ground is causing headlight and/or motor controller current to return through the hi-beam indicator causing it to stay on.

If the hi-beam indicator is on only when the headlights (either hi or low beam) are on, then the broken ground is between the left headlamp and the headlight motor controller. (Trace between the connector on the back of the headlamp, through the short harness on the headlight assembly then through the connector between the assembly into the harness to where the ground from the headlight motor control unit (small black box in the left-forward of the engine compartment) connector enters the harness. If the hi-beam light is on all the time (headlights off or on) then the ground break is between the controller and the rest of the stuff on that ground leg.

The stuff on that ground leg includes: Left engine compartment light, LH Horn, LH Cornering Light & the headlight motor controller for both headlight motors. If most of those things are working OK I'd put money on the black wire close to the headlight or the actual connector to the sealed beam itself. If that's not the case, your break is probably buried inside a harness. In that case, the easiest fix will be to run a ground wire from somewhere near the headlamp to a solid frame ground point. (Unless you are a purist. If so, then it's harness repair--no picnic.)

Hope this helps....

Happy SuperBowl results everyone!

MANY MANY thanks PJ!! I checked it out and the ground connection at the headlight plug was either loose or not making a good connection. If I take the ground wire off the light it remains dim, but as soon as I put it back on, or connect a new wire to the ground upstream of the headlight plug harness it comes on bright and the high beam indicator goes off. It's working fine for now, but I will try to replace the ground connector at the light as soon as the parts store opens in the morning. You have really saved me a bunch of heartache and money on having someone check it out. Hope you have a good Superbowl Sunday and best wishes.

Keith

PJ, do you think it is possible that the black connector on the headlight where all three wires make contact with the light could be allowing current to travel between the green high beam supply and the black ground wire? When the ground is connected and the beam is dim there is a slight current on the green connector at the light, according to my light tester. When the light works as it is supposed to there is no current on the green wire if the lights are on low beam. Just trying to figure it out before I go hacking wires to replace connectors.Thanks again for the help you have given. Hopefully one day I'll be able to return the favor.

Glad to help Keith.

It really sounds like you've got a major break in that ground line from the left headlamp and possibly a minor problem downstream from there. I've forgotten what the right and left front engine compartment grounds look like. Those might be contributing--particularly if the car has ever played in some deep gutters or flooded streets.

This morning, "Management" has me cleaning up the residue from yesterday's bash. (as many dead soldiers in the pool as in the trashcan on the patio--plenty of rib-soaked paper plates in the flower beds etc. etc.) C4 is several blocks away in a buddy's feed barn but uncovered. I'll swap cars late this afternoon and "stare aimlessly" at the grounds for the forward engine compartment. Then will wash it for tomorrow's commute. Today started foggy but we've moved into a windy 'Santa Ana' condition with plenty of dust falling out of the sky.

Should have an answer (or dumb look report) for you tonight or early tomorrow.

You're really getting into this exotic acquisitions and properties thing PJ.

Dad Soiled latex life containment vessel

Don't know about the connector but found the grounds. On the '89, each is on the frame extension right over it's respective horn. I pulled one and found only a slight surface rust under the lug. But, a lockwasher was holding to clean metal. Might be worth pulling them and checking for any rust under the washer. Hope all gets well.

At this age, one has a lot of stuff!

-- guy with the most toys wins!

Yeah, bet you clicked the, "buy it used" button on amazon.com. {{:~[ .... PJ

pffffffftttttttt LOL Didn't know Trojan made a Shrivled and Wrinkled Compatible version. Are they rigidly reinforced for "Her Pleasure"?? hehehehehe