Help! Dead diesel advice: touch battery cables together? Anyone heard of this?

[mikeypoo]

A friend of mine has a tdi and the battery died recently, we tried jumping it today and could only get it to run for less than a second and then it would shut off. I searched the tdi forum and found this:

http://forums.vwvortex.com/zerothread?id=1479694

This guy had the exact same problem and he replaced the battery. His car would only run for less than a second. Someone advised him to disconnect the battery cables from the battery, wait a couple minutes, then touch them together. For whatever reason, he said it worked.

Has anyone ever heard of this? It seems like it might cause some damage but then again, the battery isn't connected to the car when you touch the cables together.

Why would this work? I'm hesitant to try it. Any advice would be greatly appreciated!

[Chmeeee]

You idea sounds ridiculous/terrible.

I will tell you something about TDI batteries though, you typically can't jump them off of most other cars. The batteries are so much more powerful (in order to crank the diesel), that the current actually flows in the wrong direction.

[GermaniuM]

Why not pull the battery and charge it with a battery charger. If that doesn't work then go from there.

[CosmicTDI]

Quote, originally posted by mikeypoo »

A friend of mine has a tdi and the battery died recently, we tried jumping it today and could only get it to run for less than a second and then it would shut off. I searched the tdi forum and found this: http://forums.vwvortex.com/zerothread?id=1479694 This guy had the exact same problem and he replaced the battery. His car would only run for less than a second. Someone advised him to disconnect the battery cables from the battery, wait a couple minutes, then touch them together. For whatever reason, he said it worked. Has anyone ever heard of this? It seems like it might cause some damage but then again, the battery isn't connected to the car when you touch the cables together. Why would this work? I'm hesitant to try it. Any advice would be greatly appreciated!

If it's starting and running, then shutting itself off, it's the immobilizer not the battery. I have never heard of doing this, and I wouldn't do it. I don't know how to reset the immobilizer, so I can't help you there.


Modified by CosmicTDI at 10:00 PM 12-5-2009

[puebla]

Quote, originally posted by GermaniuM »

Why not pull the battery and charge it with a battery charger. If that doesn't work then go from there.

That is a fantabulous idea.

[The A1 and A2 German]

Quote, originally posted by Chmeeee »

You idea sounds ridiculous/terrible. I will tell you something about TDI batteries though, you typically can't jump them off of most other cars. The batteries are so much more powerful (in order to crank the diesel), that the current actually flows in the wrong direction.

No

It's a manual reset of the TPS on the TB and discharging the capacitors in the ECU resetting it. In other words, your clearing your ECU, even after voltage your ECU still retains power.
Touching both the positive and negative will discharge what ever remaining power is in the ECU.

Even after your battery is removed, touching the 2 terminals together (with out even having any source of power) you will even create a small spark, draining what's left.

ATTENTION: IF YOU HAVE AN AFTERMARKET SYSTEM WITH AMPS: Unplug it from any source of power before touching terminals.

[mikeypoo]

Yeah, I agree, it sounds like a terrible idea. I was just looking for some feedback in case someone else has tried it (since it's not my car I don't want to ruin something).

Although I did find this info regarding resetting the immobilizer from http://www.myturbodiesel.com/1...r.htm:

General troubleshooting procedures

1. First, make sure the car battery is charged. A low battery can cause problems with the immobilizer. It also results in low cranking RPM during engine start - this will cause the ECU to prevent fueling.

2. Try another key - you should have a valet key and spare key that also have an immobilizer chip in them. If they work, then you have isolated the problem to the key. Again, there is NO battery for the immo chip, it gets power from the ignition switch transmitter. You can try reprogramming the chip with the procedures linked to below.

3. Check for error codes - scan the car with a VCDS to see if there is a problem with the system and refer to the appropriate procedure below.

4. You can try just leaving the key in the ignition to "ON" but not start for a few minutes. Many people report that the light just goes away after 10 minutes as if nothing ever happened. This and the next solution appear to have something to do with a capacitor discharge or something resetting. It sounds strange but many report that it works.

5. Try disconnecting BOTH negative and positive terminals of the battery. Then touch the cables to each other only, while not attached to the battery. This can reset the immo system. Again, don't touch the cables to the battery, touch them only to each other while both are disconnected from the battery - you don't want to short the battery out. Also step on the brakes - this turns on the brake lights and discharges any stored electricity.

6. Check wiring and plugs at instrument cluster and pickup coil at the ignition switch, there is a chance it could be faulty.

[winstonsmith84]

Quote, originally posted by Chmeeee »

You idea sounds ridiculous/terrible. .

Actually it is not. I can't speak for VW's but I have done with on my V70 to revive a dead climate control module. I disconnected the battery with the key out. Apparently that is a huge no-no. The key needs to be in "position 1" to keep from frying several components. Touching the cables somehow resets the systems. I've seen this on several boards and the dealer tech told me the same. Might work for VW's too.

[mikeypoo]

so when you touch the two battery cables together, the key needs to be in the ignition in the first (running) position?

[Deserion]

I can't vouch for touching the car's cables together sans battery, or leaving the key in.

When I've needed to mess with the airbags, I usually turned the lights on, then disconnected the battery, and waited about 15 minutes (just to be sure), and went from there. YMMV.

[The A1 and A2 German]

-Unplug the battery

-Wait ~5-10 minutes

-Connect both terminals together for leave them be for ~30 minutes +.

-Reconnect to battery and start

To be safe, remove the battery completely before hand, I have not heard key trick, probably draining any power left.

[VDub2625]

Quote, originally posted by mikeypoo »

so when you touch the two battery cables together, the key needs to be in the ignition in the first (running) position?

Probably not. Anything with a memory that can be reset will get power from the battery itself, not through the ignition key.

[veedubtek]

There's no need to wait. No need to keep them together very long. We fix alot of strange electrical problems this way. Unhook both battery cables, hold them together for 10 seconds or so (or use a jumper wire if they don't reach), reconnect and see what happens. I've seen this fix immo issues, odd shifting problems, MFSW controls inop, dead radios, keyless access issues, etc...YMMV of course, but it's an easy thing to try.

[puebla]

Quote, originally posted by mikeypoo »

so when you touch the two battery cables together, the key needs to be in the ignition in the first (running) position?

i am a tdi owner and I have never heard of this.

[XR4Tim]

It's a capacitive discharge, and we do it at the dealership all the time. You don't need to have the key in on VWs, and it only takes about 10 seconds to complete the discharge.

[jerk]

Quote, originally posted by veedubtek »

There's no need to wait. No need to keep them together very long. We fix alot of strange electrical problems this way. Unhook both battery cables, hold them together for 10 seconds or so (or use a jumper wire if they don't reach), reconnect and see what happens. I've seen this fix immo issues, odd shifting problems, MFSW controls inop, dead radios, keyless access issues, etc...YMMV of course, but it's an easy thing to try.

^^ This. You don't need to hold them together 30+ minutes.

[feels_road]

No need to do it so dramatically. Just use something with significant power consumption - like depressing the brake pedal for 10 - 20 second so the brake lights softly flush all remaining charge.

[SSLByron]

Quote, originally posted by feels_road »

No need to do it so dramatically. Just use something with significant power consumption - like depressing the brake pedal for 10 - 20 second so the brake lights softly flush all remaining charge.

Or push the horn or something.

There are plenty of easy ways to do this.

[bhtooefr]

While I don't think that'll cause damage on the TDI, I really don't think that's it.

There is no throttle body to reset on the TDI, BTW.

Anyway, if you have a secret key code for the car (IIRC, 2003ish and older came with the SKC,) hook up a VAG-COM or VCDS, and program all the keys to the car.

If not, there are ways to get the SKC.

[VDub2625]

Quote, originally posted by PassSedanGLX »

Or push the horn or something.

Eh, old VW horns (not sure on new ones) need the key on

[puebla]

Quote, originally posted by jerk »

^^ This. You don't need to hold them together 30+ minutes.

Definitely, 30 minutes is overkill.
Whats wrong with disconnecting the battery, hitting the brakes, horn, etc.... and letting the car sit overnight?

I believe its called a "hard reset" or something of that nature.

[VDub2625]

Quote, originally posted by hazw8st »

Whats wrong with disconnecting the battery, hitting the brakes, horn, etc.... and letting the car sit overnight?

Because if you're disconnecting the battery already, might as well just touch 'em. And it's quick, why let it sit overnight?

[Das Borgen]

Quote, originally posted by CosmicTDI »

If it's starting and running, then shutting itself off, it's the immobilizer not the battery. I have never heard of doing this, and I wouldn't do it. I don't know how to reset the immobilizer, so I can't help you there. Modified by CosmicTDI at 10:00 PM 12-5-2009

on mk3s to reset the ECU (and probably the immobi also) you need to remove the battery and leave it disconected for about an hour or so

the touching of the cables serves to complete the circuit and drain it of residual currents

seems in line with my prior knowledge and past experience

do it

side note: make sure you have your radio code or else you won't be able to unlock your radio once you do the process. The dealer can give it to you if it is OEM and you can show proof of ownership ( title or registration).... They should not charge you

[mikeypoo]

Yeah she has the radio code, not that it will do any good considering her radio died for no apparent reason. Maybe doing this hard reset will bring it back. We'll see.

[mikeypoo]

Success! It worked! Although the battery ended up being completely shot. Thanks to all who commented with the advice! And the radio works now too!

[puebla]

Quote, originally posted by mikeypoo »

Success! It worked! Although the battery ended up being completely shot. Thanks to all who commented with the advice! And the radio works now too!

No freaking way!
I have been left speechless.

How bout some pics of said TDI?

[chetacer]

If the battery is more than 4 years old, it needed replacing anyway. They don't last forever.

[justanotherusername]

This is a common practice of a lot of microproccesor based controllers, like the ECU in a car.

The reason it works is it completely discharges everthing, and forces a hard boot. Many times that will overwrite bad data with default settings, and the problem is solved.

There's no danger at all from touching the two battery cables together, and it's the best way to do this. Mashing the brake lights or horn isn't the same thing, because the discharge path still has the resistance of bulb between the two sides of the power supply, and it's possible the ECU will be isolated well enough that it won't get the job done.

[TurboWraith]

Quote, originally posted by Chmeeee »

You idea sounds ridiculous/terrible. I will tell you something about TDI batteries though, you typically can't jump them off of most other cars. The batteries are so much more powerful (in order to crank the diesel), that the current actually flows in the wrong direction.

What? No. Just no.

They may have a higher CCA rating, but thats it. Current flowing backwards on a diesel? (Ok, yes, technically speaking all electrons flow from the negative to positive, but that has been the case since the beginning of batteries) Where do you get this?

[justanotherusername]

Quote, originally posted by TurboWraith »

What? No. Just no. They may have a higher CCA rating, but thats it. Current flowing backwards on a diesel? (Ok, yes, technically speaking all electrons flow from the negative to positive, but that has been the case since the beginning of batteries) Where do you get this?

TDIs get special electrons. You didn't hear?

[SVTDanny]

Quote, originally posted by Chmeeee »

You idea sounds ridiculous/terrible. I will tell you something about TDI batteries though, you typically can't jump them off of most other cars. The batteries are so much more powerful (in order to crank the diesel), that the current actually flows in the wrong direction.

I hope you are not serious.

[puebla]

Quote, originally posted by justanotherusername »

TDIs get special electrons. You didn't hear?

[bhtooefr]

I can jump any 12 volt system with any other 12 volt system.

It might have to sit charging a while, but it will eventually charge.

The only time the current will flow "backwards" is if the diesel has a higher voltage than the car jumping it. Translation: Don't jump a 12 volt diesel with your old 6 volt Beetle, and don't jump a 24 volt diesel (stuff larger than full-size pickups - the full-sizes use two 12 volt batteries in parallel to get higher current, but at 12 volts, whereas bigger stuff uses two 12 volt batteries in serial to get 24 volts) off of something 12 volts.

A TDI is going to be a 12 volt system, just with a bigger battery.


Modified by bhtooefr at 1:05 PM 12-7-2009

[MikkiJayne]

Quote, originally posted by justanotherusername »

TDIs get special electrons. You didn't hear?

Special heavy duty ones

[SSLByron]

Quote, originally posted by MikkiJayne »

Special heavy duty ones

Same with Hybrids. That's why the electric motors have so many torks: high-output electrons.