No Battery Light

caminuvik · Jun 29, 2020

Had just replaced the alternator pulley and the regulator, thought all was well. Went for a trip, dash lights started coming coming on; the alternator not charging - half arse prepared- brought a battery charger with me, and used the charge and drive technique to get home (just to make it more challenging the battery charger began to fail-then failed.) Checking it over noticed no battery dash light, no power at the plug for activation of the alternator. Is there a fuse for this circuit? Would the led bulb be blown and need replacing, or more importantly what have I got myself into? 2004 Jetta wagon tdi bew, 5speed. Thanks

Vince Waldon · Jun 29, 2020

No fuse, very unlikely the LED burned out, and most likely it's backed up with a series resistor anyways in order to pull enough current to excite the alternator.

Could happen, but much more likely there's a wiring issue at the alternator plug/harness, or your new regulator is defective.

With the alternator unplugged you can ground the excitation wire (I do it thru an incandescent test lamp, for safety) and then switch on the ignition to test the cluster and wiring therein.

caminuvik · Jun 29, 2020

It is a two wire plug. I take my test light, ground it, insert into one terminal, turn ignition on, and see what appears on the dash, if no difference then try the other wire. One would be a ground, thus no change?

caminuvik · Jun 29, 2020

It is a two wire plug. I take my test light, ground it, insert into one terminal, turn ignition on, and see what appears on the dash, if no difference then try the other wire. One would be a ground, thus no change?

caminuvik · Jun 29, 2020

Tried both and no battery light, with ignition on, tried both wires again but watched the test light, did not show power.

Vince Waldon · Jun 29, 2020

Actually neither are grounds... one goes to the cluster to activate the BAT light, the other goes to the ECU to monitor alternator load. The alternator grounds thru its frame.

Under normal conditions neither will light the test light itself... a test light in this circumstance is just a safe fuse-like way to ground the BAT connection. If there is a short the light will come on, rather than melting something.

All this assumes a test light with an actual incandescent bulb. The above won't work as well with a LED-style test light, which has a much higher resistance than a light bulb.

caminuvik · Jun 29, 2020

I assumed one would of been the exciter wire (live), and the problem with that circuit. I used the test light with a incandescent bulb.

Vince Waldon · Jun 29, 2020

Ah... I guess a question we should have asked is: did the light not work BEFORE you replaced the regulator?

caminuvik · Jun 29, 2020

Yes, it was working before and the alternator was charging.

caminuvik · Jun 29, 2020

Its flashing lead me to change the pulley and regulator

Vince Waldon · Jun 29, 2020

Yup, flashing certainly sounds like a pulley clutch on the way out.

Wire ok at the alternator plug? Didn't bend and break while being unplugged and re-plugged?

Something changed while you were doing the swap.. but what?!

caminuvik · Jun 29, 2020

After the swap was getting 14.44, thought it was good.

wonneber · Jun 30, 2020

Where did you get the regulator from?
Was it real Bosch?

You should get power to one of the wires (key on) going to the regulator, blue one if it's the same as 2003.

Also (long shot) clean the ground cable connections including under the battery tray.

caminuvik · Jun 30, 2020

Roseland Technical Services. Regulator is a Topran, for 120A Bosch. Yes I thought one should have power. I will check with a multimeter today, and will pull battery and clean ground terminals. I just don't want to deal with under the dash. Thanks

caminuvik · Jun 30, 2020

Vince Waldon said:
Yup, flashing certainly sounds like a pulley clutch on the way out.
Wire ok at the alternator plug? Didn't bend and break while being unplugged and re-plugged?
Something changed while you were doing the swap.. but what?!

Checked plugs, pins not bent or broken, also had continuity to junction under, the battery box.
Would trying a reconditioned alternator be a sensible step at this point?

Vince Waldon · Jun 30, 2020

If you still have the original regulator it might be worth trying that first.

The fact that you're getting 14.4 out of the one you have suggests it's working OK internally, but perhaps there's an issue with how it's driving the signal.

caminuvik · Jun 30, 2020

Brushes are well worn, but it made the battery light flash under higher rpm, then most rpm. Thanks good idea.

Vince Waldon · Jun 30, 2020

Or maybe the clutch in the pulley did, right? You swapped both of them at once?

caminuvik · Jun 30, 2020

Did them both at the same time, almost. Did the pulley, test drive, battery light upon higher rpm, home and did the regulator, all then seemed good.

caminuvik · Jul 2, 2020

Thought about just changing back to the defective regulator to see if the battery light would come on, but decided to just put a bosch reconditioned alternator in (would need one sooner or later, just bite the bullet). Discovered 2 things, the reconditioned one's pulley is not the clutch type; that the box had this information pamphlet in it. Tried to attach photos - but. The pamphlet said as Vince did, ground the wire, then "if the warning lamp does not light, then the lamp circuit is defective and must be repaired. Check for a defective bulb or open circuit" Thought I would change the pulley to the one I purchased and then put the reconditioned alternator in, but unfortunately I do not seei that hepling- but what else to do? I have no idea of how to chase this battery lamp circuit- it's good to the connection under the battery.

Vince Waldon · Jul 2, 2020

Well, as I'm sure you know you've got to have that clutched pulley... at least eventually.

In terms of the wiring, you could check for a loose/corroded connection where the car's harness plugs into the cluster.

Failing that, all (remaining) fingers kinda point to the cluster itself, rare as that is.

caminuvik · Jul 2, 2020

Just tried the hail mary, didn't work out. I already had the new clutched pulley on the old alternator, just changed it over to the new one and put it in. No charging but much quieter in that area, so probably good to have the reconditioned alternator in place. Not looking forward to chasing that circuit through the firewall, but guess at the cluster would be the place to check, and I would imagine I will have to pull the dash to get at it.

Vince Waldon · Jul 2, 2020

Actually the cluster comes out surprisingly easy as far as I remember... two screws. And the dash stays behind.

Can't remember if the steering wheel has to come off.. don't think so...but if you Youtube it a bit you should be able to find a HOW-TO somewhere.

Or, someone else here will know for sure.

caminuvik · Jul 2, 2020

Thanks, you tube here I come.

caminuvik · Jul 2, 2020

Every thing looked good, terminal 12 is Generator warning light (K2), terminal 61 . How would one go about testing to see if power was coming to this terminal? If it had power would that indicate a burnt lamp? As I believe that repair parts are not available, the next step could be replacing the cluster.

caminuvik · Jul 3, 2020

I have a cluster from my other tdi, 99.5 jetta, any idea if I put that in the 04 would it tell me about battery lamp - lights or not - or could it do more harm else where. Possibilities are : 1) poor conection in wiring- alternator to cluster. 2) faulty dash cluster- burnt out lamp. 3) main CPU done

jayb79 · Jul 3, 2020

Check out this video
https://www.youtube.com/watch?v=r1zRbcdIJkk

caminuvik · Jul 3, 2020

Thanks, yes I saw that. I have no power to excite the alternator also. A little different setup, but how to fix it? Still curious about trying another cluster- it would help to rule out the cluster or know it's the problem.

jayb79 · Jul 3, 2020

The immobilizer is tied to the cluster so you would need the key from the doner other than that it should not cause any problems

caminuvik · Jul 3, 2020

Would that be the ignition key? Which I have, I do not have a grasp on the immobilizer key part. I thought I would take the cluster from the 04, which is out. and connect it in the 99.5 and see what happens. I am charging a battery for the 99.5 now, will check battery lamp works before pulling cluster.

No Battery Light

Well-known member

Top Post Dawg

Well-known member

Well-known member

Well-known member

Top Post Dawg

Well-known member

Top Post Dawg

Well-known member

Well-known member

Top Post Dawg

Well-known member

Top Post Dawg

Well-known member

Well-known member

Top Post Dawg

Well-known member

Top Post Dawg

Well-known member

Well-known member

Top Post Dawg

Well-known member

Top Post Dawg

Well-known member

Well-known member

Well-known member

Top Post Dawg

Well-known member

Top Post Dawg

Well-known member