M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Electrical => Topic started by: lqbanotxano on February 19, 2012, 10:31:58 AM
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Electrical problem???
Yesterday after driving in the heavy rain with the wipers, lights, fan & radio on I had a problem. The radio started flickering on & off. The ABS light came on. Then the check engine light came on. The check engine light then started flashing. Finally, the check engine light & the ABS light stayed on. I noticed that the check engine & ABS light were very dim. I turned the lights, wipers (hoorah for Rain X), radio… everything off. I was in the middle of a country landscape & had to wait 15 minutes till a gas station. I noticed that if I touched the brakes (applied brake lights), the ABS & Check Engine lights would dim. AT the gas station there was shelter from the rain…I checked battery & looked over the engine, alternator but did not notice anything. The engine was not turned off. The alternator, It did not seem like the alternator was charging. My destination & help, was another 30 minutes away…so I tried to make it with what battery charge was left. Pulling out of the gas station & waiting till the car was doing 50mph, I put the car in neutral & turned the car off. After a few seconds the car was turned back on & restarted in 3rd gear. The Check engine light was off & the ABS was on. A few seconds later there was a “click” & the radio came back on & the ABS light got bright. My destination was reached without any more problems. While at my destination, a stomp test was done. The engine trouble code showing was 1286, which is “nock sensor” The alternator was tested & it was charging normally. I drove the car home with radio on only (rain had stopped) & had no further problems.
I think the problem is a bad ground somewhere, not the nock sensor. I actually had a tank full of 93 octane while this was all going on.
Other than cleaning the battery terminals well, what other grounds/contacts/wires should I check?
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First off, I'd get the battery load tested at a place that knows what they're doing. If it's not accepting a charge you'll see this again.
I'd also check the alternator brushes and connectors, as well as the grounds under the hood and the instrument panel.
Sounds like you had a severe voltage drop, that'll make all the systems behave erratically. You can make a DIY voltmeter...or buy a cheap EBay one to see what's going on with your charging system.
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My alternator has 186,000 miles on it. I think that I will get it overhauled first.
Do most of you get a rebuilt with core exchange or get the one off of car rebuilt?
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That's an even better idea to get the alternator and battery tested. A new Bosch regulator has new brushes and is only about $40 IIRC. I'd just swap the regulator out and see what the old one looks like. Disconnect the battery while swapping, of course.
A good alternator shop could have that done for you in about 15 minutes though, probably charge you even less (if you can find one).
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The pos terminal on the battery was not very clean. Cleaned both terminals, aapplied terminal cream & retightened. Will look into overhauling the alternator Monday anyway.
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I called the auto electric place that I have been using for 20 years. A complete overhaul of my excising alternator will take 2 days & cost $100.00.
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That seems a little expensive...but overhauled units are pricey as well. IIRC like $350 plus the core.
I'd say run it & see if the problem comes back.
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Hi all, nubie to the forums here. I'm a German car tech and just bought a 1991 318is.
@lqbanotxano: Agree that the alternator is a good place to start. Easy DIY test is measure volts while running. Should be well above 12 volts and stay that way even with accessories turned on. You could also be on the right track with the bad ground theory. That would explain the erratic lights. They could be serving as a ground for something that lost it's own ground but is connected in some way to the light circuit. Lifted grounds do some strange things... good luck hunting it down.
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Got my alternator out & went to change the brushes. The brushes looked good…. So, I took the alternator to the alternator rebuild shop. They said it was good.
If the alternator is good, then what could be causing my battery light to flash on at idle sometimes? What caused the system to quit charging while under load & 15 minutes later start charging again?
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Could be that the battery isn't taking a charge. The alternator and battery work as a pair...if you have a dead or sulfated cell, the battery won't accept enough of a charge. Then the alternator can't "keep up" with the current drain and you end up with a voltage drop across the system.
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The ground strap from the alternator to the chassis was much corroded. The actual crimped ends were fine but the braded copper wire was not. The braided copper wire had all the outer insulation gone & corrosion throughout. The insulation gone probably did not change the grounding ability…I don’t know if the corrosion would. Anyway, I am changing this strap.
I went to 3 different brand parts houses looking for grounding straps and was met with glassy eyed stupor. I then asked for #2 or #4 bulk wire & asked if they could crimp ...same glassy eyes. Looks like I will have to make my own tomorrow…they booted me out of the last parts store at 9:00PM.
It is hard being an old fart dealing with supposed progress.
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The ground strap from the alternator to the chassis was much corroded. The actual crimped ends were fine but the braded copper wire was not. The braided copper wire had all the outer insulation gone & corrosion throughout. The insulation gone probably did not change the grounding ability…I don’t know if the corrosion would. Anyway, I am changing this strap.
I went to 3 different brand parts houses looking for grounding straps and was met with glassy eyed stupor. I then asked for #2 or #4 bulk wire & asked if they could crimp ...same glassy eyes. Looks like I will have to make my own tomorrow…they booted me out of the last parts store at 9:00PM.
It is hard being an old fart dealing with supposed progress.
I had this EXACT same problem--the wire looked ok but was corroded inside so that my alternator wouldn't charge.
I found a replacement cable in the battery cable section of an Autozone. It's a heavy gauge copper wire that I was able to fit with some coaxing.
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I just came back from a test ride. It looks like the problem is fixed.
Today I stopped at a Car Quest Auto Parts in a small town. They actually knew what a ground strap was & promptly sold me one.
Tonight, I reinstalled the alternator using the new heavier ground strap. Everything works! All the lights are brighter & my air conditioner works. During the test ride, the high beams, air conditioning, radio etc…were all on at the same time. Cycling the air did not dim the head lights. The door locks are now working properly also. All this trouble from a lousy bad ground….
Tonight was also my maiden voyage with the Mark D 91/7000RPM chip. I did not do a lot of heavy foot stuff. The main concern was testing the electrical gremlins. What little testing was done with the Mark D shows more power around 3-4,000RPM. Going 70MPH on 5th & stepping on the gas…the car has more power. One can drive the car with less down shifting while cruising around.