Little help with auto electrics?

[truckemup97]

My step-bro has been chasing gremlins for a few weeks, and I though some of you guys might be able to help out. Here's what he sent me:

99 Chevy Cavalier. The low beams don't work, but the high beams and all my other lights work. The daytime running lamps (which are the high beams on low power, plus other marker lamps) are intermittent. The DRLs should come on when the engine is running and the parking brake is off, and go off if you turn on the headlights.

The fuses are all good. The DRL relay in the fuse box is good. There are two relays wired into the lights behind the front bumper, but they're both good. Also, the headlight/turn signal switch assembly on the steering column is good. (I have some items I'm hoping AutoZone will take back).

At this point, I'm thinking it must be a corroded or loose wire, somewhere. It's probably a ground wire because the low beams have power coming in, but aren't lighting up. Quite a few of these wires run under the battery tray, which seems like a good place to start, if difficult to reach or see anything. I'm open to ideas.



So, any help here? Thanks.

 

[scooter123]

I'd suggest that you add a supplemental ground to the circuit. If it is a ground issue that will probably fix it. Use a VOM to identify the hot leads and then splice into the opposite lead and attach it to the alternator casing or something similar that's well grounded.

If that doesn't solve the problem the next place I would look is the headlight switch in the dash, they do wear out and when that happens it can cause all sorts of oddball issues.

 

[diamonback68]

Did you check the bulbs?

 

[MotoShot10R]

I initially also thought bad wire....physical connection but not electrical connection. I would look at all connection points and make sure that they are clean and clear of corrosion. I would also make sure that they have dielectric grease on the contacts where applicable.

Lack of proper grounding can make a vehicle do all kinds of odd things. You might want to take some grounding straps and throw them on the engine in different places... and just see what you get. If your problem goes away, then yeah the grounds are an issue. Too many grounds aren't going to hurt anything but bad grounding can make a vehicle go nuts. The sporadic and sometimes unrepeatable or randomly-repeatable nature of the grounding issues can be enough to drive you up a wall if you let it. Sorry I am kinda just regurgitating what you are also saying...but that is what I would do.

 

[norm]

Good advice from diamondback. I have actually had this happen a number of times . I spent many years as a chevy mechanic.

 

[26Ford]

Verify the bulbs are good, then check for a bad ground.

 

[mtgianni]

I am not familiar with the Cav. but if it isn't the bulbs I think they usually have a breaker in the switch not fused with one time fuses. Grounds, wires or a bad switch are the order I wold look at.

 

[tomf52]

Autos today have what is called a GEM, general electronics module. From your description, it sounds like the gem is either failing (has failed) or it may possibly have lost it's chassis ground. It is located up under the dash in most applications. These modules control all vehhicle lighting apps.

 

[zercool]

Since the DRLs are sensitive to the parking brake being on - is the switch there going bad? My truck doesn't have DRLs, but does have the little "BRAKE" indicator on the dash. If I hit a bump hard or nudge the e-brake handle wrong, it'll come on. A quick press down on the handle takes the pressure off the switch.

As to ground issues at the bulbs ... I'm inclined to think not. Most auto headlights have three connectors: high, low, and a common ground. If the high beams are OK, the ground is OK.

 

[truckemup97]

Quick update: He's figured out that the DRLs aren't actually a problem. Apparently, they are programmed to come on when the brake is released, but they are deactivated when the headlights are turned on. The deactivation resets when the ignition is switched off. That is what lead him to believe that the DRLs had a problem. Now we're just dealing with no low beams. He did replace the bulbs, which may have been when the situation started. He said the bulbs seemed dim, so he replaced them. Any chance that one of the bulbs was bad and is causing the entire low beam system to short out or shut off? Thanks for all the replies so far.

 

[sipowicz]

Sorry...can't help...thought you said auto erotic.

 

[truckemup97]

Sorry...can't help...thought you said auto erotic.

If you can work auto electrics into that, you just might have the next ABC primetime hit!

 

[wamalo]

You stated in your first thread:

"Also, the headlight/turn signal switch assembly on the steering column is good."

How did you make that determination? Did you remove it and check all it's functions?

In my experience, the first symptom of a failing headlamp/turn signal switch (what is typically called a smart switch) on a GM "J Body" is that the low beams will not work in cold weather. You might find that they might work as the weather gets warmer, but I suspect you need a new switch.

Replacing the switch is involved, but not difficult. Make sure you either disconnect the battery or air bag fuse and wait about 15 minutes before removing the air bag module. Take care not to break off one of the two horn connector tabs that engage the steering wheel. Push in and turn to remove. Re-install the same way. The air bag module is secured to the steering wheel either by screws (earlier) or clips (later). You'll need a puller to remove the wheel. The switch can then be removed and replaced.

My son has over 160,000 miles on his '97 Sunfire. He's replaced two thus far, but it recently failed so he will be replacing it again shortly.