Strange Things That Fix Cars

Volkswagen electrical repairs

We talked yesterday about getting stuck as an auto mechanic. Like I said it happens to all of us. So today I thought I would share some auto mechanic secrets. 😉

Over the years I have seen some strange things. You can read just about any Shop Shots post to get an idea of some of that stuff. There have also been some really weird things that have fixed cars. These are all real. I could not make this stuff up. Trust me, I have tried.

Hard Reboot aka Battery VooDoo

Volkswagen electrical repairs

Thanks to a fellow VW tech for this pic

This is my go to repair. When ever I have a strange electrical issue I do this. It is basically a hard reboot of all the car’s computers. It is kind of like your computer at home. Sometimes it gets stuck in “stupid mode”. Or like my old TV. Sometimes the sound would not work. If I pulled the plug out of the back, then plugged it back in, it would work. That TV just died. HA

To perform the “battery voodoo” Disconnect both cables on the vehicles battery. Then touch them together. I generally leave them for about 5 minutes or so. This will reboot the entire car. It forces all the modules in the car to recheck themselves and talk to each other. There is probably a million different things that this has fixed. It is fun to watch new technicians faces when they learn this for the first time.

This is generally the first things that VW tech line tells us to do when we call them. One word of caution. If a car has to batteries, disconnect BOTH batteries, or make sure you don’t try and start the car. It turns out that a Phaeton will start with the convenience battery disconnected. It then sets the jumper wire on fire. 🙂 Oh, another word of caution, don’t put out car fires. Just let the car burn.

Soft Vehicle Reboot
While this does not fix as many issues as the battery voodoo, it does do some cool stuff. VW had a flash update a few years ago.Sometimes when the update finished, the MIL would be on. There would be no codes stored, or information given. The light would stay on until you locked and unlocked the car. Why? Your guess is as good as mine, but it worked.

There are 2 ways to soft reboot a car.

  1. Simply turning the ignition on and off. That is called a key cycle. That will make the car do a partial reboot. Plus many sensors need to see a key cycle before they come online
  2. The second way is really simple, but sounds tricky. All you have to do is get out of the car, and get back in. If you get out of the car, lock it, unlock it, and perform a key cycle, the car will do a full soft reboot.

From time to time we have issues with cars not communicating with our scan tools. The fix was a the full soft reboot (#2). The soft reboot is nice because it does not delete all the cars values like the battery voodoo. This is a good first step specifically for a customer.

Unplug The Problem Module
This one is pretty new to me. We had a guy in the shop going round and round and round with an issue on a 2001 or so Passat. He replaced what he thought was the issue. Double checked, then triple checked his work. He tried to do the battery voodoo and it didn’t work. Left with little choice, he called VW tech line. They told him to unplug the module for about an hour. Would you believe that fixed the issue?

It seems that some of the older cars get stuck in “stupid mode”. That was the first time I have ever seen that happen. I know that he felt great to get the car fixed, and even better knowing he didn’t mess up the car.

Recode The Module
Most, if not all, modules in cars have a coding. That is what tells the module what it is, and what features the car has. Recoding that module performs a hard reboot, but only on that module. The best example is the older Touaregs and Phaetons. When I would run into a strange electrical issue on either one of those cars, I would recode the “Gateway” module. That was like the main communication point for all the modules in the car. I would go into the module with the scan tool and recode it. I would not change the coding, but recode it to the same coding. The coding was 6, and I would just recode it to 6. That would force that “Gateway” to recheck the entire system. It worked like a charm.

On the newer cars, this is not such a great choice. Codes are now “long coded”. Instead of being a coding of 6, it is more like 015b05661a0000001b. Getting that coding wrong can be a disaster. I miscoded a convenience module on a 2007 Passat one time. Many things didn’t work, but when you opened the trunk, the gas door opened. When you opened the fuel door, nothing happened. I had to call VW and get the proper coding.

I have no doubt there are many other strange things that fix cars. Do you know any? Post them up in the comment section. I know I get a kick out of that type of thing. I am sure that everyone else will too.

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8 replies
  1. Brandon Byron
    Brandon Byron says:

    “Don’t put out car fires. Just let the car burn.” EXPLAIN!!! lol Is there a reason not to try doing this? Will it just make things worse.

    • Charles
      Charles says:

      I have seen a few cars that were victims of fires.
      One was a B6 Passat. It came from a body shop. Some welding slag caught the sound dampener on fire. It took a few months and tons of wiring repairs to fix. The cost was more than the car was worth. I didn’t work on that one.

      This one I did. It was a 2004 Phaeton. I was having issues with getting the TPMS to work right. I disconnected the convenience battery to reboot the system. Well I guess it some in someone’s way. My co worker, and good buddy, jumped in and moved it. The wire that I used to connect the terminals caught fire. Nothing major, just some charring on the trunk carpet and, oddly enough, the TPMS module.

      That Phaeton haunted me for the next 2 years. I don’t think it had anything to do with the fire. I spent more time working on that car than any other car. The customer hated it. We hated it. So my policy is to just let it burn HA!

      • Jeremy
        Jeremy says:

        Haha, I read that part and thought the same thing. It seemed as if you were talking from experience. Let it burn, lol

  2. Uwe
    Uwe says:

    > On the newer cars, this is not such a great choice.
    > Codes are now “long coded”. Instead of being a coding of 6,
    > it is more like 015b05661a0000001b.
    > Getting that coding wrong can be a disaster.

    There’s software out there which easily lets you copy & paste those long codings. 😉

    The second soft reboot method sometimes needs more patience. Get out, lock it, and leave it alone for half an hour. Why? The German word is: “Busruhe”. This happens after all the modules go to sleep, and that can take 20 minutes or so.

  3. Brett Donadeo
    Brett Donadeo says:

    Glad you explained why to let a car burn. I was really curious about that myself!

    Your story about the TV reminded me of one I had. After it had been around a few years, it started doing this weird thing where the picture would shrink. Just sort of compress from the top and bottom, with some static at the edges. It would only do this after it had been on for a while, and you could fix it at first by banging on the side of the TV, but later in life it needed to be turned off and back on before the problem went away. Eventually, it got to a point where the picture would be compressed when you turned it on and it was just unwatchable. Turns out, the soldering was crap and had melted from the heat of the TV being on. I guess it would resolidify when the TV was off and then melt again while the TV was on. Weird stuff.

  4. rich anderson
    rich anderson says:

    i have a 2002 vw bug my friend hooked a jumper wire to were the fuel pump relay ngoes to pump out fuel that had water in it the jumper wire started smokeing he pulled it out … now the dash lights stay on with the key off and the pump keeps running please help


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