[quote=Setech;2021019]
Oftmals ist das Masseband verantwortlich./QUOTE]
das kann garnicht oft genug wiederholt werden, aber die meisten glauben es einfach nicht.
Hier mal kopiert von Gestern aus USA:
VERY weird starting issue - solved
Car:90 735i,thread copied from 10-10-2012 till today(excerpts)
A few months ago, my car had trouble starting. Thinking it was the battery, I was getting ready to swap it and realized that battery I had needed more distilled water. Topped it off, and problem went away. (problem was, what sounded like, very weak starting - like the starter almost wouldn't turn over)
A month later, the problem returned. Only, this time, a replacement battery didn't change anything. I left it on a trickle charger for a few weeks, made sure the battery was fully charged and as soon as I tried to start it, it sounded very very week. Well, last Friday I took it to a battery place thinking they may be able to test it better. Of course, my charging system is working fine, and the battery tested good too. Shut the car off, and try to start it, nothing. It just makes a moaning sound for half a second and stops. Next thing you know, after a few tries, the starter starts smoking. Naturally, we assumed it was the starter.
I swapped it tonight, and it STILL DOES THE SAME THING! I'm at a loss here. Battery is fine and starter is good. What do I do?
--------------------
You can check the voltage at the starter motor terminal when it is cranking. This is pin 30h with a BLK/GRN wire on it. This is the actual voltage on the starter motor, rather than the battery voltage. (See pg 1240-01 in the ETM.)
Maybe there is a bad connection through the cable or the starter relay, so the starter motor is starved of voltage?
--------------------------
The cables seem to go bad and reduce voltage.
Make sure you check both positive and negative cables.
Quick electrical class
Voltage is applied and amperage is drawn so if you reduce the voltage then the amperage draw is increased. Example (just an example) if a starter motor draws 30amps at 12volt then at 6 volts it is drawing 60amps. That is quite a huge jump in amperage and more than enough to burn a starter motor out.
------------------------
Easiest way to check the voltage at the starter is by unlocking your OBC. One of the options is system voltage at that terminal. Search. "Unlock OBC" for directions and options. It is very easy to do and especially in your case worth it
-------------------------
quote "Make sure you check both positive and negative cables."
Good point! The GND strap from the engine block to the chassis could also be corroded.
You could hold the Blk meter lead on the engine block and the Red meter lead on the BLK/GRN wire, while the starter cranks. This would be the true voltage across the starter motor.
Unwanted voltage drops might be found:
1. from block to chassis
2. from charger post to BLK/GRN wire
3. From battery negative to the chassis
4. From battery positive to the charging post.
xxxx - I see that the BLK/GRN wire goes to OBC, but I do not see a Starter Voltage test function on the OBC, just a Battery Voltage function. Did I miss it?
------------------------
Any thoughts on why my starter would have smoked previously? Too much current, maybe?
-------------------------
If the starter motor is not getting enough voltage to generate enough torque to turn the engine, then it is in stall condition.
Stall causes smoke and heat in DC motors, when there is high supply current. The commutator is stuck on one segment pair and the fan is not turning. It's just a big electric heater.
--------------------------------------
Originally Posted by E32FAN
"I see that the BLK/GRN wire goes to OBC, but I do not see a Starter Voltage test function on the OBC, just a Battery Voltage function. Did I miss it?"
Isn't the system voltage taken at the starter? I was under the impression that Terminal 'R' referenced in the OBC higher functions is starter positive terminal
__________________
Lets say there is a big voltage drop over the starter. What causes that??
------------------------
@AVEC: Jeff, check out pg 0140-02 at
http://www.e38.org/e32/e32_92_etm.pdf
It defines the following symbols:
30 is "Voltage Supplied At All Times" (See pg 3435-00 where X16 pins 12 & 13 are supplying 30 inside the Instrument Cluster.)
15 is "Voltage Supplied In Run or Start" (See pg 3435-00 where X16 pin 7 is supplying 15 inside the IC.)
R is "Voltage Supplied In Accessory, Run, Or Start" (See pg 3435-00 where X17 pins 3 & 15 are supplying R inside the IC.)
31 is GND
@SeanH:A big voltage drop across the starter relay is bad, because it's supposed to be a switch.
A big voltage drop across the starter motor is good - it creates torque to turn the engine over.
Each of #1 - 4 above should be a small voltage drop - 0.25 volts say. This would leave the majority of the battery voltage to be applied across the starter motor.
My guess would be a bad connection at the charging post, since others have reported troubles there. So if you measure 12V to GND at the charging post and 5V (say) at the thick Blk cable to the starter terminal while cranking, then you will want to renew the thick Blk cable.
------------------------------------------
Alrighty, did a little testing today. Voltage over the starter (the largest connection, which looks to be coming off the power charging post) and grounding on the engine - before starting it's a solid 12v, while turning over it drops to 7-8 volts.
My friend said to check over the solenoid too. However, I'm not sure which connection is which. Is the smallest wire the switch and the other larger wire the power for the solenoid, and the huge wire (which I checked) it just for the starter motor itself?
---------------------------------
OK, and what is the voltage at the charging post while cranking? Is it staying up at 11.5 - 12V range?
While cranking and making this measurement, hold the meter's Blk probe on the chassis, and then on the Block, to see if there's any difference.
------------------------
Just an update. I started comparing starting voltage when grounding to the engine and then to the chassis. It dropped more during ground to the engine. I went to go change my ground strap and noticed one of the nuts was loose. Tried the one off my other car - WOLA - all good! Put the old one back on and tightened it down - PERFECT.
Wow...the amount of time I wasted on this is insane. I think I've learned my lesson.
Sie sind nicht angemeldet! Jetzt 
kostenlos im Forum registrieren, weniger Werbung sehen, aktiv teilnehmen und weitere Vorteile nutzen! Diese Website nutzt Cookies. Bitte beachten Sie unsere 
Hybrid-Darstellung
