All lights dimming frequently when engine is running. Saturn SL1 1999..HELP.

i think i have the same problem too. but it might be the battery. mabye some loose connections on the battery terminal. because when your car starts to move the connections will become loose. but other than that i dont know what to tell you. it seems like i have had some kinds of flucuation in my dash lights too. or maybe you can adjust you dash light knob and put the setting on high.

Yeah...I tried adjusting the the setting all the way to high. It does it less, but it still does it. But, I think that just covers up the problem. I still have my headlights dimming and my air fan fluctuating....I have to nip this one in the bud. Thanks, anywho...appreciate the advice.

• Check the battery connections and that they're tight and clean. if the battery's more than 2 years old, replace it.

• Your alternator could be acting up. Can you replicate this problem in your driveway without moving? If so - measure the voltage at the battery terminals and see if it goes up and down. Use an analog meter here.

• Check for loose/broken/corroded ground straps.

Yes, I was able to replicate the situation while parked with the engine running. It seems that when I take my foot off of the accelerator, the engine idles very low, and then back up to where it should be. When the idle goes very low, I can feel the car slightly vibrate, like it was thinking about stalling, but changed its' mind.

I'll check my battery. If anything that I just said in this entry helps you determine my problem more, PLEASE share that with me. I appreciate all of the help so far. Thanks.

Yeah. It's starting to stall and the computer's trying hard to keep it from doing that.

Check the charging system with a voltmeter. I'm almost certain you've got a charging related problem , or a corroded connection. It should be making decent voltage (13 volts - anyone got a better number here?) at idle (1000 rpm or so). I dont' think it should 'pop up' when you rev the car.

See if the voltage goes up at the battery whenyou rev the engine. If so, suspect the alternator or the cables leading to it. I'd start by cleaning all the connections - taking them apart and making sure they're clean, oil free, and assembled good and tight.

Naturally, disconnect the battery when you do this :)

And, check the ground connections and ground straps between the motor and body. They all come together on a stud on the motor, IIRC. Clean it good, make sure it's dry, oilfree, and tight.

Ditto for the connections at the battery.

If it's still acting up, then suspect the alternator. When you replace the alternator GET A NEW BATTERY. A bad battery can waste the alternator, and vice versa.

Once you've got a stable charging system that's working right, the car should idle properly. if it's not, then you need to totally clean the throttle body. Actually, if yours looks dirty now, I'd do that before replacing anything but the battery (but do check those connections!) I like to remove it and remove the TPS and IAC and clean it totally, then wipe the IAC off so it's clean and reassemble. It's really easy and logical.

I just posted this reply in a similar post, but I had the same problem and gave up trying to have the dealer solve the problem (4 trips and not once could they fix it). The first thing I noticed on mine was the ground was a little loose so I started by cleaning it and tightening it. Didn't help much, still there. Next thing I did was removed the rubber boot on the cable end for the ground, it seemed like the rim around the face makes it hard to get a good connection. You can trim the ring down with a razor blade but if you're not careful you'll end up removing it anyway.

Next I put in a second ground strap (using 4 gauge wire) from the motor to the chassis, using the same mount point on the motor and picking a new spot on the chassis after cleaning it to the bare metal. I also ran a second ground from the battery to the chassis and a second ground from the battery to the motor (I was able to do this with a slightly longer bolt in the battery, not to long or you'll crack the case. I also removed that rubber boot like mentioned before so it worked out better). After all these were checked for continuity, I cleaned the ground block which is behind the left headlight. Finally I sprayed all the connections, motor, chassic, and ground block (not the battery post) with some gloss black spray paint, this slows any corrosion and rust from forming.

Yeah, this seems a little drastic having all the ground connections, but I also have a high end stereo system and this helps eliminate noise. You may be able to get away with a second ground from chassis to motor only. The extra grounds may also help eliminate any ESD fluctuations that can occur, which I believe was also happening to me when it was raining and wet outside. It's a cheap and easy fix (any automotive parts store should have pre-made ground straps for cheap).

sorry, one last thing, when checking the charging system, it should be atleast 13 at idle, and will reach around 14.6v when you rev the engine. Once you hit 1000rpm you should see it reach 14.6 and should not drop or go much higher. If it drops when you rev the motor up further you're voltage regulator isn't doing its job and should be replaced.