No Battery Light

For testing purposes, it should work fine but it will shut off as soon as it starts if the key doesn't match the cluster. There is a small chip in the key.

Yup, you'll know as soon as you turn the key to ON if the BAT light suddenly works.

You won't know if it will charge, since the engine won't run for more that 5 seconds with the mismatched key.

But if the BAT light does come on you've probably found your issue.

I think if you hold the matching key within about 1/2" to the ignition it would start, assuming the light comes on and you want to test charging. After its running for 30 seconds, you can move the key away.

Tru dat... new cluster should be OK if it can see the key it's tuned for... doesn't have to be the one in the ignition itself.

That said, dunno if it will get confused with both keys in proximity.

Thank you, looking forward to trying this tomorrow. I was going to ask if the key could be close to other key, good to know the 1/2" , good point at being confused with two keys.

Some reference reading for immo and keys,
http://forums.tdiclub.com/showthread.php?t=340192&highlight=immo

Well, the cluster is good, both worked in the 99.5 and neither in the 04. Holding donar key on the ignition key it would just start and die. Any idea what the next step should be?

If you do the test light check like in the video does it go out? In the video, he was connecting the test light to positive (@2:43 he says battery positive).
https://www.youtube.com/watch?v=r1zRbcdIJkk

I have installed a Bosch reconditioned alternator. Where he has one wire, on this one there are 2 wires. Was concerned which one to connect to, or both,. Also this would just prove the alternator is bad, I have new one, maybe the old one was good with the new regulator? Where does voltage come from to power the lamp and alternator. Then how to check that?

Look at the vid 1:03 you will see his has 2 connections and you can see what one he puts the light on. One wire is power and the other is ground, they feed the connections to the rotor thru the regulator. So one of your wires should connect to ground the other you already know gets power thru the light. You're going to have to trace that wire back until you find power.

I traced back to under the battery, then it disappears into a harness maze of wires. Need to find out where the next connector is and check there? I am way over my head at this point. Oh well.

As above, on your TDI one alternator wire is excitation, the other is a feed to the ECU for load monitoring, NOT GROUND.

(Using caps so you don't accidentally blow something up. )

Dunno where a 1-wire alternator would have come from, but won't work properly in your car.

Best to track down a wiring diagram (if you haven't already) to confirm which is which. You can ignore the ECU wire while troubleshooting and just focus on the excitation wire. It should read 12V with the key set to ON, and should turn on the BAT light when grounded.

To answer your previous question, excitation voltage comes from the battery, thru the ignition switch, thru the BAT LED/resistor in the cluster, and thru the excitation wire to the regulator. Hence seeing 12v on that wire with the key turned to ON.

As the battery lamp is not getting power, it could next be between the ignition and the cluster, I need to look for a connection at the ignition. Hope it is as easy as the cluster. Need to get more acquainted with my Bentley, schematics are a hard read there. Thanks

Do other things in the cluster come to life when you turn on the key (fuel gauge/temp gauges, for example) ?

If so, the cluster is getting battery power thru the ignition switch and you've pretty much narrowed it down to defective circuitry in the cluster or an issue between the cluster and the alternator.

Swapping out a known-good cluster would be the super-fast way to prove this one way or the other... don't need to start the car to see if the BAT light comes on.

Vince he already swapped out the cluster with a known good one in post #37 , neither worked in the 04 , but they both worked in the 99.5 so it’s not a cluster issue.

Ah, right. Threads getting long.

I missed/not sure I understand what this means:

caminuvik said:

Well, the cluster is good, both worked in the 99.5 and neither in the 04.

Click to expand...

Or do you mean both your clusters worked ok when physically installed in your 99.5 car but not in your 04 car?

If so, yeah, issue must be between the cluster and the alternator: plug connection or perhaps chaffed wire in the harness.

Wiring diagram should show which exact cluster harness pin is the run to the alternator, for a continuity test.

Yes, both worked in the 99.9, battery light did not work with either in the 2004. Surprisingly the 99.5 after sitting for 4.5 years, started immediately, no cranking just fired right up. I would assume I have continuity from this plug to the alternator (plan on checking), as it seems the issue would be power not getting to the cluster. Power must be needed to feed the light and the exciter wire. This would come from the ignition? This pin #12 is the only pin related to the generator in the connector/ cluster and seems is for power to the lamp.

The cluster needs power to turn on the gauges, run the clock, etc etc etc... and excite the alternator.

So, if the gauges are running and the clock is running the cluster has power and that's not the issue.

Ok, power to the cluster, except for bat light, what to check for that. Nose in the Bentley, need a magnifying glass. Have identified the cluster, Gen warning light, goes through T32 pin connector, position 12, going through a blue wire to a # 4 in frame/box ( which is "Number in frame indicates current track where wire is continued. ") need to figure out this current track. Got that figure out, I think.

Just did a continuity check on cluster to alternator wire - as expected no continuity. Didn't notice connection plugs shown, wonder if there are some. The wire at the alternator is a lot thicker than at the cluster.

Rats!

If you remove the battery and air filter you'll see a black rectangular plastic cable tray on the drivers side that goes down the back of the engine compartment and under the battery. Most of the engine compartment wiring goes thru that passage.

The lid to the cable tray pries off pretty easy, exposing most of the cabling. Common wear points are wherever the cabling passes thru an opening.

If memory serves there's also a second bundle of wiring that goes thru the firewall behind the turbo, about in the middle of the firewall.

caminuvik said:

Just did a continuity check on cluster to alternator wire - as expected no continuity. Didn't notice connection plugs shown, wonder if there are some. The wire at the alternator is a lot thicker than at the cluster.

Click to expand...

Pin 12 from the cluster should be the blue wire going to the alternator.
It should be one piece to the alternator as far as I can tell.
Pin 1 at the cluster (black / violet) should get power from fuse 11.

I was looking through that mess of wires and having a problem finding a blue one. I will try and colour match at pin 12. Very intimated of having to open wiring- bundles. Have also been in the process of getting a square body on the road for transportation.

I now have a battery light, not sure what I did to solve it? Wires seemed good, poor connection? Left it alone for awhile, got back on it today, and something worked out. Thought I was going to have to part it out. I have a problem with these self healing / solving issues, as I don't think I learned anything, and no eureka moment. Thanks for all the help and suggestions.