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Reprogram Basic Settings When Power Is LostPosted 10/12/2003By Jim Newkirk
It was a dark and stormy Friday afternoon when the tow truck rolled into the shop parking lot with the Volkswagen Jetta hanging forlornly behind. I could see the owner of the car was nervous and shaking. He walked to the counter and said those words that struck fear deep into my heart: "All I did was replace the battery and now it won't run right!" We've all heard horror stories of batteries connected backward and power spikes striking to the heart of the electronics. What if I told you that in this case, the battery was replaced perfectly, no damage had been done to any systems and still there was a hard start plus poor performance condition to contend with? Let's take a look at a 1999 Volkswagen Jetta 2.0L and see if we can unravel the mystery. Starting in 1996 on OBD-II vehicles, Volkswagen began using an electric throttle control module to control the throttle plate. This throttle control module contains an electric motor that actually moves the throttle plate and two potentiometers that monitor throttle plate position and requested throttle position. The throttle controller is synchronized to the powertrain control module (PCM) electronically. This matching process allows the PCM to memorize the closed throttle, wide-open throttle and pre-start throttle positions. If power is lost to the PCM or throttle controller for any reason (disconnecting the battery is the most common reason), the synchronization between the PCM and throttle controller is erased! This synchronization is known as the "Basic Setting." As hard as it may be to believe, basic settings are stored in volatile memory and are erased whenever power is lost from the PCM or throttle controller. In addition to the basic settings for throttle control, Volkswagens with automatic transmissions will have the transmission basic settings erased as well. So you see, a simple battery replacement is not so simple and definitely not something a do-it-yourselfer would want to perform. How do you unravel this tangled mess? Basic settings must be reprogrammed using a 100 percent VAG1551 factory-compatible scan tool such as a BAUM CS 2000 or a Snap-On MT2500 with the latest Volkswagen cartridge. 1) Reset basic settings if any trouble codes are stored in memory. Record all codes before clearing. Some codes, especially those relating to the throttle controller, can be set during attempts to start the vehicle after battery replacement. Record the codes to compare those returned after reset with the original codes set. 2) Connect the scan tool to the vehicle and enter engine electronics (Engine word 01 on the VAG 1551). 3) Check for stored trouble codes. Record and clear them. 4) Enter Basic Setting (Address word 04 on the VAG 1551). 5) Once Basic Setting is active, enter the display group number 098 or 060 (check the manual for the specific code for the vehicle you are working on. Throttle basic settings are activated using different display groups depending on year, make and engine package). Once the display group is entered, the Basic Setting relearn (also known as adaptation) begins. 6) The scan tool will display a screen containing four fields.
7) As the relearn process proceeds, the PCM will command the throttle controller to close the throttle, open the throttle to wide open, close the throttle a second time and finally move the throttle to the pre-start position. During this process, Field 4 will read "ADP runs." The PCM memorizes all positions and the relationships between the sensors during this process. Once the process is complete, Field 4 should read "ADP OK." If it reads "ADP Error," adaptation was unsuccessful and should be repeated. Be sure the battery is fully charged and that the throttle is not touched during the adaptation process. After performing the throttle basic setting, check, record and clear codes once again - then start the vehicle; the car should now start and idle normally. Once the throttle basic setting is complete, proceed to the transmission basic settings (automatic transmission only). 1) Enter Transmission Electronics (Address word 02 on the VAG 1551). 2) Check for stored trouble codes. Record and clear. 3) Enter Basic Setting (Address word 04 on the VAG 1551). 4) Once Basic Setting is active, enter the display group number 000 (be sure to check the manual for the code specified for the vehicle you are working on). 5) Transmission basic settings are activated using different display groups depending on year, make and engine package. 6) Depress the throttle fully and hold for three to five seconds (to allow the transmission control module to memorize kick-down position). 7) Exit the field. Check and clear stored codes again. The resetting of basic settings is complete! The vehicle should now start, idle and drive normally. Mystery solved! Armed with the right tools and a bit of knowledge, even the most mysterious vehicle can be diagnosed and returned to service as good as new!
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Copyright (c) 1996-2010. Automotive Service Association®. All rights reserved.
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