Subpage of MembersPage/MarcellGal/PowerAndTraction
This (originally 3B) engine has a
- 90A (or 110A ?) Bosch alternator
Alternator Belt (outer V-belt of the 3-belt crankshaft pulley)
Always keep an alternator belt in the trunk (and 10, 13mm tools) if you have a 3B (or AAN,ADU,ABY) engine.
- Very small footprint and cost and very nice to have
- since it's the most likely part in these cars to fail;
- (note: next is the factory clutch pedal at least with a very strong race clutch)
- Belt: 820mm long, 11.2 mm wide (not 9.5mm or 10mm wide and not polyV)
- Gates V Belt: 11A0825 (AUDI 100/200 2.2L Alternator, 1983-87 and 1988-91)
- gates.com 6313MC (11.2 x 820La) seems to work well so far
- I keep a Quinton Hazell in the trunk, along with 1x13 mm and 2x17mm tools to be able install it at the roadside anytime
Alternator connections
- a THICK red (obviously positive) wire with 8mm ring connector. I cleaned the connector surface before securing. In my install +12V (always live VBATT) coming from the starter mains
- the alternator body is ground
- Alternator excitation - read below
The voltage-control electronics is integrated inside the alternator (it's a 20..25 EUR item available separately, eg. at Budapest. XVII Petri u 7. alternator repair-renew-shop).
MembersPage/PaulF - Most smart alternators that I have dealt with fail safe to an output voltage of around 13.8V. Usually it is to allow the charging voltage to be lowered at idle to help pullaway. It is also used for feedback to the ECM as to the load on the alternator for torque adjustment.
Even without the excitation connection, there is some charging with running engine, appr. 13.7V
- higher than 12.5V means charging
- but less than 14V means the charging current might be low. Most likely the failsafe mode of the alternator. I heard that the acceptable range is 13.8-14.8V
It charges somewhat .. maybe suboptimal, but it works.
Alternator excitation
Needed for proper inducing the alternator. Without bulb or when this circuit is open, the alternator might not induce up or just very slow.
Note that the alternator was working (for me at least, with slightly reduced voltage) even without excitation. But, after an unfortunate series of events (our galaxy almost got annihilated) when I lost the alternator-belt
- I decided that I want immediate indication of lost (or snapped) alternator-belt
- The smart dash senses dropped voltage and shows a battery pictogram with some delay (appr 3 mins with headlights, fuelpump and radio on)
The alternator excitation circuit:
- ignition key, switched +12V
- red lightbulb on instrument cluster. Upper-left red lamp, with battery mask.
- lights up if there is some problem with charging (or engine is stopped)
- thin (0.5mm2 or so) wire at the alternator
- everyone said color is light-blue - but mine was black
- 5mm ring connector
On the wire I measured +12.5V with ignition on (0V with ign off)
- I pulled down the wire to ground with a 22Ohm resistor
- than I measured 4.88V with ignition on, and the audi 200 instrument cluster upper-left red "charge-problem lamp" lit up. Very reassuring, that's how you can test if unsure.
- note: the calculated resistance of the indicator lamp is Rlamp = 22 Ohm / 4.88 * (12.5 - 4.88) = 34.4 Ohm
Many thanks to MembersPage/ZoltanAlmasi
Alternator belt
I had lotsof hassle with the alternator belt.
- The orig belt was squeaking
- mostly during gearshifts, and when the big fan starts
- we applied a new belt that worked for a few days, than overturned and got rounded and burnt (became useless, except maybe for lifting ;-)
- the orig belt applied again, worked for a few months
- the belt was lost on 2007-10-10. Because of lack of immediate charging indication, I noticed it a bit late: the dash-computer only warned when VBATT started to drop, and it took some more time for me to take it seriously (first I thought it was a bad indication).
- I installed the spare belt at the roadside (I had it in the trunk, with good prediction it would be needed). I think I got the tension right. It was squeaking a bit, but with the almost drained battery I had to keep it running (it might not have supported another cranking), and I lost the belt again, in about 10 mins.
WTF is happening ?
- bad beltsize ? 11.2mm, not 9.5 or 10mm
- Emil says audi might have somewhat own pulley profile. Always order belt for the given engine. A "similar belt" will likely NOT work even if length matches.
- bad tension ? I think I can get the tension right, but ... who knows...
- slippery pulley? The valve-drive simmering seems to spread a very small amount of oil (which sucks, I paid for brand new simmerings when engine was rebuilt a few months ago). The alternator V-belt pulley gets a little wet with oil, I'm sure this is not very good. The squeaking is not surprising.
- dirt in the pulley ? I know it tricked others, but I think not in my case (we cleaned it)
- crankshaft-pulley rubber dampener stiffened in cold ?
- this might make it more likely to lose the belt during sudden RPM changes, like gearshifts or +3600 RPM/sec acceleration in gear1 (from 4000 to 7600 RPM in 1 second!)
So after I lost the alternator belt (snapped or jumped off ? dunno) TWICE: Than in a rush to find parking place downtown, I stuck a concrete and killed the bottom oil-cap and the right-ear of the charge-cooler broke.
It was a really bad combination:
- wheel in hole
- concrete at worst place
- while running without charging
- rush to find parking place downtown
- I parked at the neighbor place last week which was perfect
- the stupid concrete at this place was really naughty
- it was also dark, and running at a crazy speed (for parking), I noticed the danger too late
- typical Titanic situation ;-)
Oil-change was about time anyway
- I had a spare bottom-oil-cap to install, but I wasn't aware that type needed a separate shield for the flywheel
- the broken-off charge-cooler ears are no fun, hack-fixed it for now
Ghost current
When ignition is off, measured current draw from the battery is 0.37A. This means I have to charge with a battery charger if parking more than 3 days so I can start the car after.
What draws the ghost current ?
- The small pushbutton lights of the automatic windows are lit (only seen in the dark), and the automatic windows work without ignition => that must be it !!!
- hint from MembersPage/TeppoKalske : they work after ign off until you open the drivers door and close it. After that they don't (should not) work.
- mine continues to work => maybe the drivers door button or wire is haywire
- the drivers door button must be good, as the interior roof-light reacts
- there was some hack in the left door, with the power wires, result of not proper earlier repair. My car electrician located and fixed it in a few hours, after lotsof curses ;-)
Power windows links
- see the schematics
- the front left door window motor control is different, because it
- has only 1 set of pushbuttons (1 up and 1 down). The other 3 windows has 2 sets: a local, and another at the driver.
- can go all the way with just a short tap on the button (the buttons of the other 3 windows must be pushed as long as one wants the window to move)
- also, the rear window motors are powered from the drivers (front left) door "safety switch", that allows to prevent kids-tampering
- keywords: audi power.window.control unit front.door.switch
- [operation, with USA-EU differences]
- [with pics]
Other possibilites that were candidates for ghost current
- some light in the trunk or under dash or glovebox ?
- alternator
- radio ?
- immobilizer ?
- central locking control system ?
- the central locking system must be powered even with ignition off
- cabin-heating or climate system ?
- there is some strange box under the glovebox with appr 10 color (thick, 1mm2 or so) wires going to the mid-box, it was for the heating and air-conditioning system. It was disconnected at that time anyway