Odd Electrical Issue, w/ Video.

[Nsquared97]

So I tried to start my car to get to work today ('87 325is, M20B25, 5spd etc.) and it acted as if the battery was completely dead. Didn't even attempt to crank, no lights on the dash at all, etc. Took my buddies car to work, just got home and tried it again, here is what it's doing when I turn the ignition to run:

I put a battery changer on the battery, but with a DMM I am reading 12.3-12.5V across the battery, so I don't think that's the issue, and it was new less than a year and a half ago.

Only electrical issue I can think of lately is over the last two days the engine oil idiot light (not the check light, the one in the cluster) would flicker occasionally when I let off the gas to slow down for a stop light. Other than that the car has been running just fine.

I am guessing maybe a relay or something, I am going to start looking through wiring diagrams and see if I can figure anything out. Any help is greatly appreciated.

[blueapplesoda]

fyi the engine oil light in the cluster is the low engine oil pressure light, usually when the engine sees less than 3 or 5 psi or something. I'm not sure if its related.

Have you tried jumping the car?

[Nsquared97]

fyi the engine oil light in the cluster is the low engine oil pressure light, usually when the engine sees less than 3 or 5 psi or something. I'm not sure if its related.

That's what I figured it meant, but I am *assuming* it isn't related. What would cause this, bad oil pump? Like it said it only flickers very briefly, and only when letting off the throttle. Doesn't happen at idle.

Have you tried jumping the car?

I haven't yet, I was planning to let the battery charge for a while and then see what happens.

[xtos]

Check the voltage on the battery while cranking the engine. Then check the voltage on battery + and CHASSIS - (not on the battery) while cranking. Although it looks like a dead battery , might be a bad/loose ground. Batteries showing over +12 with a respectable dmm usually are good, but may not have enough amps, so it's dead. I say respectable cause some cheap PRC dmms have a +-2v offset.

[jlevie]

The behavior in the video matches the symptoms of a dead battery or a fault in the primary power circuits. After the battery has been on a charger overnight, disconnect the charger and wait 30 minutes. Then measure the battery voltage with a DMM. If the battery accepted the charge it will read 12.7v. If the problem is still present, monitor the voltage at the battery posts while someone turns the key to start. If it remains at 12.7v, there is fault or bad connection in the primary power circuit. If the battery voltage drops significantly, the battery is bad.

[Nsquared97]

Thanks for the responses guys, much appreciated.

So here's an update from today. Jumped the car this morning, she fired right up. Let it sit for a bit to warm up, then took it out to try and charge up the battery some. My plan was to drive enough for the alternator to charge the battery, then let the car sit while I was at work (didn't trust it enough to take it to work, didn't want to be stranded there when I got out). The car ran like absolute crap. Up to ~2500rpm was Ok, then it would buck/sputter/kick like crazy. Took this video when I got back home, just reving the car in neutral, but it behaved very similar driving with the engine under load as well.

Also, what is that green light for that's lit up? Has arrows facing left/right? I have seen it come on at random times before, but very brief and very sporadic. Not sure if that has anything to do with this or not, but it was on the whole time I had the car running.

So, once I got home from work tonight I checked the voltage at the battery again, 12.5V. Tried to start the car, turned the key to run and everything lit up like normal, tried to start and just got a click. After that all the lights died like they did in the original video.

I haven't had a chance to try the tests you guys mentioned, I am going to attempt those in the morning. Unfortunately I don't have a helper so watching the voltage while cranking could prove to be tricky. I'll see what I can figure out tomorrow.

[eduTechnic]

You ever figure out what was up? I have half my instrument lights out (after removing the dash to fix the odo gears an fiddling around taking out SRS wiring/computer under the dash) and the same pattern of lights on the dash staying on, including the oil pressure light, despite changing the oil during all the maintenance. I recently had the car out on the highway, stopped because I believe I air-locked the t-stat, and went to start it up 30 min later after it cooled down and no turnover whatsoever, had to get jumped.