[rattlenbang]

Hey all, I was driving down the hwy when all of a sudden my 2005 new beetle TDI shat the bed. Warning lights started flashing: abs, traction, oil, the dash was beeping, all the tranny letters flashing. Suddenly no drive on transmission. Glided to side of hwy. Engine was running ok. Shut it off, restarted, but soon as it started, tranny letters flashing. Then the warning lights, tach bouncing randomly, dash beeping. Soon, engine would start but immediately die. I checked the voltage on battery terminals: 11.8 volts with headlights and flashers going. Engine running, 13.8 V. All fusible links on battery checked ok.
I would swear it was a voltage problem but at least at the cables voltages were good.
Don't have a manual with me or my vag com. Not sure where to start on this thing without a schematic. It seems neither the ecu nor the tcu is at all happy.

 

[UNA2003]

Sorry about your misfortune, unfortunately your problem is above my pay grade. Good luck, stay safe.

 

[David A. McDow]

You should start with a full scan and see if the scan reveals anything obvious.

 

[burgman400]

@rattlenbang How old is the 12v battery? How many years?

 

[Bernie-san]

If you suspect a voltage problem, have the battery tested on a bench at one of the auto parts stores, usually a free service. If ok, check all of the ground connections you can find in the engine compartment. I usually check for tightness, condition of cable to connector connection and signs of corrosion. I usually remove the ground connections, clean them with a wire brush or sanding paper and then apply dielectric grease before reinstalling.

 

[tdisrgr8]

Had similar symptoms with an 04 Jetta. Found obvious melted plastic on fusible link box on top of battery. All fusible links were good. My fix was to replace the cable between alt and battery. Guessing corrosion got down inside wire jacket and increased resistance enough to cause excessive heating.

 

[Bernie-san]

If the above suggestions do not remedy the situation, try disconnecting/reconnecting the two main harness connectors under the cowling in the center of the firewall. Remove the plastic tray just below the windscreen to gain access.