Weirdness 207

[Aronis]

Hello All,

Of course I have a new problem. What else is new?

I have a parasitic battery drain. It's about 0.95 amps. I am just starting the process of debugging, but I need to get a better multimeter, mine is only good for 1 amp. The guys at Advanced Auto tested my battery with their fancy set up and the battery is good. Their tester has an inductance coil amp meter and it showed at 0.95 amp drain. (yes all the doors were closed, etc).

So, I know it could be many things, but are there any common things in the RS6/A6 line? I turned off the dome lights, unplugged my radar detecter, checked the cigarette lighters, etc. So I don't think it's a simple thing. Perhaps a stuck relay or bad diode in the generator?

Thanks for the input.

Mike

[Aronis]

I picked up a Klein CL800 with DC amp clamp and the leak is GONE? WTF? It's intermittent I guess. ?something wet? I'll just leave the Clamp meter in the trunk and check it daily. Intermittent problems are the worst!


Mike

[G2]

It's always a goose chase. Nothing common that comes to mind. Use your clamp meter and start pulling fuses. See if the amperage drops. The car should consume 150-300mA. Ultimately you're chasing a .5 to .75amp load.

Relays typically consume far more amperage since they are designed for high load reduction (30-40amps max load). It's possible the pull in relay part of the relay is stuck on. Off hand do no recall if any are ignition switched somehow.

A bad generator diode will show a high AC voltage ripple wave. But it can consume power as it's an electrical gate of sorts. If memory serves you can use the AC setting on a DVOM and long as it's under .5V it's about right. A proper alternator test is preferred of course. The tester I have calls Bad at about 200mV. A good reading is under 25mV.

A thermal imager like the new handheld SnapOn can see the heat signature due to power consumption. Not many places have them, but I couldn't resist and got one earlier this year.

You'll surely have another chance when the Gremlin returns... Hope this helps.

[Aronis]

Thank you very much. I tested it yesterday and the leak was not showing! It's intermittent, the worst kind!

Mike

[Aronis]

The drain is not consistent. Today I charged up the car (after putting snows on) and drove it. When I got back the drain was 3 amps! WTF?

I pulled ALL the fuses in the left dash board end fuse box, and the problem was not found. It did slowly drop while I was messing around.

I tried to find the wire the the alternator? This showed a half amp once I got it isolated.

Is this the wire to the alternator?

I am now doing a 'deep cycle' charge the battery and am going to check that wire again after running the car and disconnect it and see if the battery holds a charge.

18308

18307

[bethridg]

Pretty sure those large wire plugs go to the electric fans. The alternator harness is bundled with the starter wires buried on the passenger frame rail.

[Aronis]

Interesting....the fans were not running...I'll try unplugging that connector and see....(see how hot the engine gets if I forget to plug it back in )

Thanks for the information....

Mike

[Aronis]

Finally had some time today to look at a few things. I had found current flow at the wire to the fans. COMPLETELY RANDOMLY CHECKING any wire I could get the current meter clamp around LMAO!!!!

Did a scan and found this error

17072 - ECM Power Relay Load Circuit.

As per ROSS-TECH....

Possible Symptoms
Engine Coolant Fan running at full Speed while Ignition is OFF and Engine is COLD (could lead to discharged Battery)

(I don't hear this happening now...car is quiet.....perhaps intermittent?)

Possible Causes
Fuse(s) faulty
Power Supply Relay for Engine Control Module (J271) faulty
Terminal 87 faulty/hanging
Wiring between Engine Control Module (J220) and Power Supply Relay for Engine Control Module (J271) faulty
Possible Solutions
Check/Replace Power Supply Relay for Engine Control Module (J271)
Check Wiring between Engine Control Module (J220) and Power Supply Relay for Engine Control Module (J271)
Check/Replace Engine Control Module (J220)

Still need to check the alternator wires also to check diodes, anyone have an idea if the wires to the alternator can be EASILY disconnected to do this? Or do I have to pull the engine out LOL

Mike

[Aronis]

I was ill for several weeks so did not do much......not really ill just off synthroid for a nuclear scan so really TIRED without thyroid hormone.

Anyway, I disconnected the large wire that I think was causing the current leak, charged the battery for several hours and just started the car 24 hours later. It did not turn over immediately but the battery did have enough juice to crank it and start the car. I am going to let it run for a while and see if it starts again tomorrow without using the charger.

So I do not know if that is the only current loss and I think that wire goes to the cooling fans.

Mike

[Aronis]

Started car again today, first nothing but all dash lights, so there was battery voltage, then I tried again and it cranked slowly a few times and started. So the battery is not dying overnight with the wire to the fan's disconnected, but it's not quite normal either.

I'll do the same in the morning. Going to take it to my mechanic this week, just been waiting for Christmas break so I have a ride without bothering my wife. LOL.

Mike

[G2]

Might simply pull the fuse or relay. But nothing is better than pulling the plug. Relays sometimes fail also.

Been told the a bad ECT sensor can trigger the fans. If the ECU loses the reading it will try to protect the engine by default. Have a RS6 in my care that has the same problem. See what I find out....

There's really no need to disconnect the Alternator unless it's being removed for bench testing. Prior recommendation stands in first testing for AC voltage ripple.

[Aronis]

Might simply pull the fuse or relay. But nothing is better than pulling the plug. Relays sometimes fail also.

Been told the a bad ECT sensor can trigger the fans. If the ECU loses the reading it will try to protect the engine by default. Have a RS6 in my care that has the same problem. See what I find out....

There's really no need to disconnect the Alternator unless it's being removed for bench testing. Prior recommendation stands in first testing for AC voltage ripple.

Yes, I have an idea how to test the alternator, but I have been too lazy to get under the car to reach it's wires. LOL.

Do you know if the relay for the fans is On the ECU Board or elsewhere? If elsewhere, WHERE? firewall inside car or under hood? :)

Mike

[Aronis]

Taking car to my mechanic tomorrow.

With the wires to the cooling fan disconnected the battery dies down to about 1/2 charged (as per charger) instead of down to dead. There is still about a 1/2 amp drain from unknown source so it looks like two issues.

We shall see, but probably be another grand in labor charges.

RS6 - the most expensive Audi to own.

Mike

[Aronis]

This is acting too weird. I said screw it and bought a new battery. I am not sure the 'guy at auto zone' tested my battery correctly. we shall see.

Car still runs so nice...what POWER!!!!!!!!!!!!!!!!

Mike

[Aronis]

Car started no problem today, new battery ok so far. I think that the 'low' battery messed with the electronics in the car. I have been reading about similar odd behavior with other Audi cars and low batteries giving odd symptoms.

Mike

[Aronis]

Day three. Car running great. Was it the Battery? Not proven yet but looks likely.

Mike

[Aronis]

Friday, day four, car is perfect. Spoke with another mechanic who seam knowledgable about car battery issues. He said a short in the battery can produce the exact issue I had, with current drain being noted on negative lead.

Acid test will be driving it for a month daily. LOL. RS6 back to my daily driver! M2 sitting covered in road salt in the garage LOL.

Mike