I recently brought a car that was sitting for 20+ years back to life. Runs perfect, but when I went to smog it, it failed because the check engine light never turns on. I noticed that none of the lights (brake, engine, security, etc) never turn on except for seat belt. On the way home, I noticed my battery draining quickly, so I ordered an alternator which is not here yet.

What could be causing all these lights not to show up. Certainly they cant all be bulbs? I checked a few duses including the 2 up front by the battery. All good. Possible bad ECM?

Also in my haste to remove the alternator, I didn't fully unhook the battery before, and I sparked it on the egr line. Noticed my RPM gauge is now starting off way above 0. Not sure if related but it was fine before I removed alternator.

Any help and direction is appreciated. Thank you for your time.

 

ECM doesn't work any of those except the CEL.

Try bulbs first.

What car is this?

 

It's a 1986 2.8L V6 Camaro. I planned on changing the bulbs anyway, but initially it seemed like too many coincidences to be bulbs.

 

They're incandescent bulbs... very much a limited life component.

Part # 194. Buy acoupla boxes of em at a REAL parts store, rather than buying em on cards; there's around 12 just for the gauge illumination, plus all the individual indicators.

Best way to do it is, pull the whole cluster. Which is VERY EEEEEZY: about 6 or 7 little Torx screws that hold the bezel on, then about 4 nuts that hold the cluster in. Hardest thing will be getting the speedo cable to come loose, and even that isn't all that hard. Feed some extra cable through the firewall (acoupla inches makes a BIG difference, might want to take it loose from the cruise regulator if your car has that), reach around the back, there's a sort of spring retainer that holds it in; press it down with no pulling tension on it, then pull the cluster out while holding down the retainer.

You may even find that a bad bulb is what's making the alternator not work. Believe it or don't, the alt's "excitation" current comes from the bulb in many GM cars, and in most of those, if the bulb is bad, the alt will never get "turned on" by ignition power.

 

Thank you, I'll definitely take your word for it and get right on that. I was planning on swapping to LED anyways because I can barely see the gauges at night as it is.

 

Don't use LEDs in the "Choke" or "Alt" light, whichever your car's is labelled. You're likely to end up with the same problem as a burned-out bulb as described above.

You'll find that with all the bulbs working, the dash will be QUITE bright. Also, LED colors may or may not be very appealing to you, after you spend the $$$ and trouble on them. Hard to find them that look good both on red pointers and on the white printing lit by the aqua background.

 

So a few bulbs are out, including the CEL. How can I tell which side was positive? Does it matter?

 

Positive or negative on the 194 bulb? It doesn't matter.

They're old bulbs, but I'd be really surprised if that many were burnt out. My car is 35 years old. In the five and a half years that I've owned it, I've replaced one bulb, a turn signal. All of the dash and interior lights still work, and I really doubt they've ever been replaced. With my car, it could be that the prior owner, who had it from 1988 until 2018, didn't drive much at night. The headlights are GM Guide brand lights which were OEM. The glass on them is very clear and not pitted by any pebbles hitting them. It's possible that the headlights aren't original, but GM sold off Guide Lighting before 2000, so however old they are, they're quite old.

 

Just an update in case others end up seeing this and what I figured out. I got the cluster out and changed the bulbs. There were a few not working. Unfortunately LED's are polarity sensitive, so it was a bit of trial and error until I got them all lit up. I swapped the alternator and everything worked perfect, and passed smog two days ago. Thanks for the help.