Tip & How-To about Volkswagen Passat

Car battery disconnection warning

Some new cars have radio alarms. Some have ECM and TCM codes that are erased by disconnecting the battery for any amount of time. Most of these cars are 2000 or newer, such as VWs. To avoid problems, a memory saver (or Aux voltage input device) can be used. A spare battery is also needed to power the device, which is plugged into you cigarette lighter to keep enough power in the car's systems. If power is lost, a secret code for that radio can be used to reset it. The Engine & Transmition modules will need a dealer to reset the computer with cars like VW.

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how to reset the tcm on 05 suzuki forenza

if obd2 car, is it? no country stated.so....
the TCM is transmission brain.
some cars suzuki pull the dome fuse.
in all cases ,all cars, pulling the battery neg lead does that.
but wil reset battery and tcm ecm all radio and alarms.

if in usa the correct fuse is in the fsm
alldata dot com has that online.
newer suzukis use a different fuse for the memory wire.
the TCM fuse is dead center of the 04 Forenza here. left dash side.
the op guide does not have this fuse stated. memory
only the fSM covers that, and not willing to pay $15 to find out.
alldata dot com.

key off,pull TCM module, count to 60, put back.
its now reset.

Jun 27, 2013 | Cars & Trucks

2 Answers

07 scion tc changed battery now car wont stay running unless foot on gas

If it is a brand new battery and you just installed it, it may need charged a bit. Also make sure the connections are tight on the battery and the wires are on the correct poles. RED to + and BLACK to -.

Sep 06, 2011 | 2005 Scion tC

1 Answer

car start out in second gear, po1864 came up. what does this means


P01864 means battery disconnected within last 50 starts. If this occurred occasionally, or just after disconnecting the battery, then the code is not pointing at any fault. Just telling you that the battery has been disconnected. The code will be erased after cranking 50 times.

If the problem comes back times and times again even if you have not disconnected battery in last 50 starts check crank sensor and battery wiring.

Check also oil pump sensor, cam and MAP sensor. If car starts in second gear I will also have a loot to connectors at PCM and TCM and to wiring to throttle position sensor and vehicle speed sensor.

Usually the code is displayed if the battery has been disconnected withing the last 50 starts. In that case there is no fault and the problem with second gear is not related. About the car starting in wrong gear test the solenoids in the valve body, the TPS, the wiring to TCM and the VSS. Here some troubleshooting about similar shifting problems.



Aug 08, 2011 | Oldsmobile Cutlass Supreme Cars & Trucks

1 Answer

I recently replace the battery in my 2005 Ford Mustang GT. After I installed the new battery the green light for my dealer installed alarm keeps flashing even when I am driving the car. I went to the dealer and asked how to reset the alarm so it wouldn’t keep flashing when it was turned off and while I was driving the car. The Tech told me to push the button under the dash and the green light should also be a button and to push it at the same time. I told him the green light is not a button, only a green light and that pushing the button under the dash didn’t fix the problem. He said he didn’t know any other way to fix the problem. Can you tell me how to reset the alarm light to stop flashing when it is not armed?

                Before Battery Change

                • When was/or when did you notice alarm green light illuminated?

                • When after alarm was disarmed, did green light shine?

                First thing to check would be electrical connections starting from the battery.
                1. Follow positive wire lead from battery to fuse box connections. (Should be along driver side frame rail, or near battery.)
                2. Follow wrie harness to Relay Center. (Find Alarm Relay/Fuse)
                3. Also to Power Distribution Center. (upper driver corner engine bay)
                Relay Switch and Fuse to Alarm should be okay, given the alarm green light illumination.

                The Cars Brain, ECM Engine Control Module, manages messeges between power BattV and Alarm, also other modules and various sensors throughout the vehicle.

                When Battery Supply was disconnected, something happened, that stunned the memory in the ECM.

                Yes, the alarm does need resetting, its actually the memory messages saved in ECM need to be Refreshed.

                (saying "alarm needs resetting") sounds like alarm is broken, when that is not the case. Similar scenario is, when smart phone screen webpage freezes(alarm memory info in ECU). No buttons work, not even power button (Key Fob control). Only way to gain access is to remove battery.

                Lets try an experiment, this will be to loose still/saved frozen information, stuck in computer memory.

                How to Reset Vehicle Computer.

                1. Remove Neggative Post connection.
                2. Remove Positive Post connection.
                3. Let vehicle sit over Two Minutes, this time allows capacitors in vehicle Modules (ECM/PCM, TCM), to release any/all stored voltage, also any voltage in Vehicles ground circuit will be released.
                  • (I would typically wait 15 minutes) Capacitors with out constant Voltage input, will disipate rather quickly, depending on capacity size.
                4. With Battery Still Disconnected. Open Driver Car door, and turn Ignition to RUN Position.
                5. Reconnect Positive Post.
                6. Reconnect Negative Post.
                  • IGNITION is in RUN Position, when reconnecting Battery. Driver Door Is Open.

                  7. Turn Ignition to Off.
                  • Notice if alarm green light is illuminated.

                  8. Hit LOCK Button On Driver Door Switch to Reinitialize Alarm.
                  • Be SURE Key Fob not locked in car.

Mar 26, 2017 | 2005 Ford Mustang

2 Answers

running down battery when parked for a day without usage

There's always a small amount of drain on the battery for the ECM, alarm, etc, but if draining bad within 24 hours you either have something live not wired correctly and drawing or possible short of a positive. An ASD relay that shuts off the car in case of a wreck or ECM tells it can go bad and lock into giving power to the engine nonstop and will drain that fast. Overnight it wont start the next day. This relay might also be called MFI. It has an always live 12v  on one part even when car is turned off.

Sep 05, 2010 | 1998 Mercedes-Benz E-Class

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