oilhammer
Certified Volkswagen Nut & Vendor
Thought I'd post this to clarify some of those pesky acronyms we see here all the time. This has been done before, but it has been a LONG time.
First, for any that do not know, an "acronym" is the term used for a group of letters that stand for something, and are often made into a word themselves. Some of my list contains true acronyms, some are merely abbreviations, but both are used frequently.
Automotive electronics:
OBD: On-Board Diagnostics. This is a vehicle's self-contained ability to monitor, store, and display what is not going correctly in the form of some sort of code (see below). OBD2 is the second generation of OBD that was mandated by congress and adopted globally. Most 1996 and newer cars are OBD2 compliant. The 1996 Passat TDI is OBD-D compliant, which is very similar to OBD2.
DTC: Diagnostic Trouble Code. This is the OBD systems way of informing the technician of what has gone outside tolerable limits. These can be displayed in forms like blinking lights or as alpha-numeric text via a scantool. There are MANY DTCs. Generic DTCs are displayed the same for all OBD2 compliant vehicles. If the DTC starts with P it for Powertrain, C is for Chassis, B is for Body, etc. Volkswagen however also uses a 5 digit proprietary DTC, which is all numbers. An OBD2 compliant Volkswagen will store both, but a generic scan tool will only display the generic ones, and often do not give you the full story.
EDC: Electronic Diesel Control. Sometimes used in conjunction with a number, indicating Bosch's series of EDC. For instance, EDC15 was used in TDIs with rotary pumps, and EDC16 is used in TDIs with unit pumps (PDs). The new-for-2009 Common Rail TDI will employ Bosch's new EDC17 system.
SAE: Society of Automotive Engineers. Organization set in place to set standards for a wide range of automotive protocols, including those of OBD2. A generic Pxxxx DTC is an SAE numbered code. SAE also sets the weights of lubricants, as well as little things like light bulb fitment, automatic transmission gear selector sequence, etc.
CAN: Controller Area Network. This is essentially a Bosch term. As is usually the case, the Germans set many standards for cars, and the network by which the various computers communicate within the car is one of them. The CAN is simply the network that the computers use to talk to one another, via a dedicated CAN wire, or "bus". Volkwagen has had CAN for a long time, but on US cars the system was "dumbed down" through the CAN-gateway so the scan tools could talk to the car. Most 2004-up cars now have full CAN communication protocols even for diagnostics. CAN allows for a much faster communication baud rate with the scan tool.
DLC: Data Link Connector. Usually located in the driver's footwell area, this 16 pin connector is what allows you to attach a scan tool to the car's various computer systems for diagnostic and modification purposes. If the car is full CAN-enabled, you will need a CAN capable scan tool to connect. Most 2004-up cars are like this. The size, shape, and design of the connector is an SAE standardized one, but some cars have a harder time fitting some OBD2 cables that others.
ECU: Electronic Control Unit. Also sometimes called an Engine Control Unit, but ECU can mean anything that is electronic and controls something else. Any modern Volkswagen has oodles of these. Even the glow plug "relay" is really an ECU. Same for the turn signal flasher.
ECM: Engine Control Module. Sometimes called ECU or engine ECU. This is the computer that controls the engine functions. In the TDI and many other drive-by-wire cars it also controls the cruise control.
TCM: Transmission Control Module. The computer that controls the automatic transmissions. Any Volkswagen built in the last 15+ years has an electronic controlled automatic transmission. Manual cars do not have this, obviously. Yes, the DSG is STILL an automatic transmission.
MIL: Malfuntion Indicator Lamp. Sometimes called the "Check Engine Light" ( CEL ) this is the little orange light that comes on when a fault is detected by the engine ECU worthy of alerting the driver. This merely lets the driver know a DTC has been stored, and a scan tool connected to the DLC is the only way* to retrieve it and diagnose the problem. MANY things can cause the MIL to illuminate.
* if you still have an early 1996 Passat with the BK suffix ECU running OBD-D, there is an option for blink codes by jumping two terminals in the DLC. These are mostly no longer in service due to a recall to replace them, but there may still be a few out there. However the scan tool will still also work on these.
ABS: Anti-Lock Braking System. Been around a while, I think we all know what this is. The "ABS" light will come on and stay on of the ABS ECU has detected a fault. This too can be diagnosed with a scan tool via the DLC.
SRS: Supplemental Restraint System. More than just "airbags", this is a complex system of sensors, switches, pyrotechnics that help to keep people safe in the event of a collision. Like the other systems, the SRS can be diagnosed via the DLC if the light comes on and does not go out.
CCM: Comfort Convenience Module. This is the ECU that Volkswagens (newer ones, anyways) use to control some onboard funtions like keyless entry, power windows, power locks, etc. Communication via the DLC is the same as many other ECUs.
ESP: Electronic Stability Control. This (if equipped) allows the car to be corrected via the engine and ABS systems if you go into a skid, or the wheels slip going around a turn, etc. Safety device, some carmakers call it VSC (vehicle skid control).
EDL: Electronic Differential Lock. Uses the drive wheels' calipers by means of the ABS to squeeze a wheel that is slipping under poor traction conditions to force applied torque to the other drive wheel.
ASR: Anti-Slip Regulation. Uses the engine's management to limit output to prevent wheelspin in poor traction conditions.
MAF: Mass Air Flow. This is a sensor that uses either a hot wire or hot film that gets "cooled" by the incoming air to the engine to cause a change in electrical current which the ECU "reads" to determine just how much air is coming into the engine.
MAP: Manifold Absolute Pressure. This sensor generates a voltage based on positive pressure OR vacuum in the intake system and allows the ECU to calculate the boost level in the engine in order to control the turbocharger. Many non-turbo cars use these as well for fuel calculations. Volkswagen often refers to these as a 'thrust sensor'.
VNT: Variable Nozzle Turbo. This is a type of turbocharger that some engines use that differs from the older wastegated variety. These use numerous vanes to duct the exhaust gasses past the turbocharger's compressor wheel to generate positive pressure (boost). These vanes' pitch can be varied by means of the VNT actuator which is usually vacuum controlled but sometimes electric servo controlled.
DMF: Dual Mass Flywheel. A type of flywheel that utilizes two main parts dampened internally from one another with a series of springs and gears.
Other info:
GFF: Guided Fault Finding, which means VAG's way of hand holding moron techs through a useless and convoluted diagnostic procedure insuring that they cannot think outside the box, nor draw on any real world experience with anything. It's disgusting. It turns good techs to mushroom-brained robots, and draws in bad techs to stay forever.
VAG: Volkswagen, AG. The parent company of Volkswagen, Audi, Seat, Skoda, Lamborghini, Bugatti, Bentley car lines, as well as some other smaller companies like Volkswagen Marine and Industrial engines, etc. VAG recently purchased a controlling interest in the Scania truck maker (formerly part of Saab). VAG is now majority owned by Porsche, AG.
VAG-COM: This is a PC-based software provided by www.ross-tech.com and is made exclusively for use on VAG products. Now known as 'VCDS', or Vag Com Diagnostic Software.
VCDS: see above
Mechanical terms:
CV joint: Constant Velocity joint. These are used at each end of each axle to allow the wheels to go up and down and pivot while power is transfered from the powertrain. They have boots that sometimes need servicing.
DSG: Direct Shift Gearbox. Volkswagen's fancy name for their automated manual transmission. The unit is sometimes called the 02E.
TTY: Torque To Yield. Refers to fasteners (typically bolts) that are tightened in a manner that is not measured by the actual force on them but rather done by means of measuring the rotational angle in degrees.
EGT: Exhaust Gas Temperature. This is the tempurature of the exhaust gas as it exits the cylinder head, BEFORE the turbocharger. Useful to know for modding as well as for catalyst regeneration and closed loop fuel control (PD).
IAT: Intake Air Temperature. Some cars use a sensor to read the air coming into the engine to modify fuel delivery strategies, and it can also be used as a back-up or check for the MAF sensor.
EGR: Exhaust Gas Recirculation, a mechanism to lower a specific pollutant, NOx (see below)
NOx: Nitrides of Oxygen, a pollutant formed from high temps and pressure (as inside a combustion chamber) forcing Nitrogen to bond with Oxygen.
SCR: Selective Catalyst Reduction, a mechanism to lower NOx, post combustion, using a urea (DEF, see below) injection system to release the nitrogen-oxygen bond and turn it into water, oxygen, nitrogen
DEF: Diesel Exhaust Fluid
DPF: Diesel Particulate Filter
TDI: Turbo Direct Injection. VAG's name for their newer diesel engines.
SDI: Sauger Direct Injection (may be mispelled). The non-turbo version of the TDI not sold in North America. Sauger means "suck" in German I think.
IDI: InDirect Injection. Refers to VAG's older diesels, pre-TDI (as well as many other makes of diesels before direct injection became commonplace in light duty diesels).
TD: Turbo Diesel.
US-spec TDI Engines:
VE: Vertielerpumpen, denotes style of Bosch diesel injection pump used on all IDI VAG diesels and TDIs through 2003 US cars.
PD: Pumpe Duese, denotes the unit injector diesel injection system used on 2004 through 2006 model year US cars.
CR: Common Rail, denotes the type of diesel injection system used on 2009+ US cars.
1Z: 90hp 1.9L early style used in the 1996 and 1997 Passat Bosch VE equipped
AHU: virtually identical to the 1Z, used in 1997 through early 1999 Jetta Bosch VE equipped
ALH: 90hp 1.9L late style engine, with VNT and Bosch VE injection pump, used in 1998 through 2003 New Beetle, late 1999 through 2003 Golf and Jetta
BEW: 100hp 1.9L "Pumpe Deuse" unit injector engine used in 2004+ New Beetle, 2004+ A4 chassis Golf, 2004 to early 2005 A4 chassis Jetta sedan, 2004 to 2005 Jetta Wagon
BHW: 134/136hp 2.0L PD engine used in 2004 and 2005 Passat
BRM: 100hp 1.9L PD engine used in late 2005 and 2006 Jetta sedan
BKW: 310hp 5.0L PD V10 used in various years of Touareg
CBEA: 140hp 2.0L "Common Rail" engine used in 2009+ Jetta sedan/wagon
CJAA: 140hp 2.0L "Common Rail" engine very similar to the CBEA
CKRA: 140hp 2.0L "Common Rail" engine used on the 2012+ Passat NMS (often inaccurately referred to as the B7, which uses the CFFN engine). Changes made include an air-to-water intercooler and a Borg-Warner BV40 turbo.
CRUA: 150hp CR engine used in 2015 Golf, Golf Sportwagon, Audi A3
CVCA: same as above, used in 2015 Beetle, Jetta sedan, and Passat
First, for any that do not know, an "acronym" is the term used for a group of letters that stand for something, and are often made into a word themselves. Some of my list contains true acronyms, some are merely abbreviations, but both are used frequently.
Automotive electronics:
OBD: On-Board Diagnostics. This is a vehicle's self-contained ability to monitor, store, and display what is not going correctly in the form of some sort of code (see below). OBD2 is the second generation of OBD that was mandated by congress and adopted globally. Most 1996 and newer cars are OBD2 compliant. The 1996 Passat TDI is OBD-D compliant, which is very similar to OBD2.
DTC: Diagnostic Trouble Code. This is the OBD systems way of informing the technician of what has gone outside tolerable limits. These can be displayed in forms like blinking lights or as alpha-numeric text via a scantool. There are MANY DTCs. Generic DTCs are displayed the same for all OBD2 compliant vehicles. If the DTC starts with P it for Powertrain, C is for Chassis, B is for Body, etc. Volkswagen however also uses a 5 digit proprietary DTC, which is all numbers. An OBD2 compliant Volkswagen will store both, but a generic scan tool will only display the generic ones, and often do not give you the full story.
EDC: Electronic Diesel Control. Sometimes used in conjunction with a number, indicating Bosch's series of EDC. For instance, EDC15 was used in TDIs with rotary pumps, and EDC16 is used in TDIs with unit pumps (PDs). The new-for-2009 Common Rail TDI will employ Bosch's new EDC17 system.
SAE: Society of Automotive Engineers. Organization set in place to set standards for a wide range of automotive protocols, including those of OBD2. A generic Pxxxx DTC is an SAE numbered code. SAE also sets the weights of lubricants, as well as little things like light bulb fitment, automatic transmission gear selector sequence, etc.
CAN: Controller Area Network. This is essentially a Bosch term. As is usually the case, the Germans set many standards for cars, and the network by which the various computers communicate within the car is one of them. The CAN is simply the network that the computers use to talk to one another, via a dedicated CAN wire, or "bus". Volkwagen has had CAN for a long time, but on US cars the system was "dumbed down" through the CAN-gateway so the scan tools could talk to the car. Most 2004-up cars now have full CAN communication protocols even for diagnostics. CAN allows for a much faster communication baud rate with the scan tool.
DLC: Data Link Connector. Usually located in the driver's footwell area, this 16 pin connector is what allows you to attach a scan tool to the car's various computer systems for diagnostic and modification purposes. If the car is full CAN-enabled, you will need a CAN capable scan tool to connect. Most 2004-up cars are like this. The size, shape, and design of the connector is an SAE standardized one, but some cars have a harder time fitting some OBD2 cables that others.
ECU: Electronic Control Unit. Also sometimes called an Engine Control Unit, but ECU can mean anything that is electronic and controls something else. Any modern Volkswagen has oodles of these. Even the glow plug "relay" is really an ECU. Same for the turn signal flasher.
ECM: Engine Control Module. Sometimes called ECU or engine ECU. This is the computer that controls the engine functions. In the TDI and many other drive-by-wire cars it also controls the cruise control.
TCM: Transmission Control Module. The computer that controls the automatic transmissions. Any Volkswagen built in the last 15+ years has an electronic controlled automatic transmission. Manual cars do not have this, obviously. Yes, the DSG is STILL an automatic transmission.
MIL: Malfuntion Indicator Lamp. Sometimes called the "Check Engine Light" ( CEL ) this is the little orange light that comes on when a fault is detected by the engine ECU worthy of alerting the driver. This merely lets the driver know a DTC has been stored, and a scan tool connected to the DLC is the only way* to retrieve it and diagnose the problem. MANY things can cause the MIL to illuminate.
* if you still have an early 1996 Passat with the BK suffix ECU running OBD-D, there is an option for blink codes by jumping two terminals in the DLC. These are mostly no longer in service due to a recall to replace them, but there may still be a few out there. However the scan tool will still also work on these.
ABS: Anti-Lock Braking System. Been around a while, I think we all know what this is. The "ABS" light will come on and stay on of the ABS ECU has detected a fault. This too can be diagnosed with a scan tool via the DLC.
SRS: Supplemental Restraint System. More than just "airbags", this is a complex system of sensors, switches, pyrotechnics that help to keep people safe in the event of a collision. Like the other systems, the SRS can be diagnosed via the DLC if the light comes on and does not go out.
CCM: Comfort Convenience Module. This is the ECU that Volkswagens (newer ones, anyways) use to control some onboard funtions like keyless entry, power windows, power locks, etc. Communication via the DLC is the same as many other ECUs.
ESP: Electronic Stability Control. This (if equipped) allows the car to be corrected via the engine and ABS systems if you go into a skid, or the wheels slip going around a turn, etc. Safety device, some carmakers call it VSC (vehicle skid control).
EDL: Electronic Differential Lock. Uses the drive wheels' calipers by means of the ABS to squeeze a wheel that is slipping under poor traction conditions to force applied torque to the other drive wheel.
ASR: Anti-Slip Regulation. Uses the engine's management to limit output to prevent wheelspin in poor traction conditions.
MAF: Mass Air Flow. This is a sensor that uses either a hot wire or hot film that gets "cooled" by the incoming air to the engine to cause a change in electrical current which the ECU "reads" to determine just how much air is coming into the engine.
MAP: Manifold Absolute Pressure. This sensor generates a voltage based on positive pressure OR vacuum in the intake system and allows the ECU to calculate the boost level in the engine in order to control the turbocharger. Many non-turbo cars use these as well for fuel calculations. Volkswagen often refers to these as a 'thrust sensor'.
VNT: Variable Nozzle Turbo. This is a type of turbocharger that some engines use that differs from the older wastegated variety. These use numerous vanes to duct the exhaust gasses past the turbocharger's compressor wheel to generate positive pressure (boost). These vanes' pitch can be varied by means of the VNT actuator which is usually vacuum controlled but sometimes electric servo controlled.
DMF: Dual Mass Flywheel. A type of flywheel that utilizes two main parts dampened internally from one another with a series of springs and gears.
Other info:
GFF: Guided Fault Finding, which means VAG's way of hand holding moron techs through a useless and convoluted diagnostic procedure insuring that they cannot think outside the box, nor draw on any real world experience with anything. It's disgusting. It turns good techs to mushroom-brained robots, and draws in bad techs to stay forever.
VAG: Volkswagen, AG. The parent company of Volkswagen, Audi, Seat, Skoda, Lamborghini, Bugatti, Bentley car lines, as well as some other smaller companies like Volkswagen Marine and Industrial engines, etc. VAG recently purchased a controlling interest in the Scania truck maker (formerly part of Saab). VAG is now majority owned by Porsche, AG.
VAG-COM: This is a PC-based software provided by www.ross-tech.com and is made exclusively for use on VAG products. Now known as 'VCDS', or Vag Com Diagnostic Software.
VCDS: see above
Mechanical terms:
CV joint: Constant Velocity joint. These are used at each end of each axle to allow the wheels to go up and down and pivot while power is transfered from the powertrain. They have boots that sometimes need servicing.
DSG: Direct Shift Gearbox. Volkswagen's fancy name for their automated manual transmission. The unit is sometimes called the 02E.
TTY: Torque To Yield. Refers to fasteners (typically bolts) that are tightened in a manner that is not measured by the actual force on them but rather done by means of measuring the rotational angle in degrees.
EGT: Exhaust Gas Temperature. This is the tempurature of the exhaust gas as it exits the cylinder head, BEFORE the turbocharger. Useful to know for modding as well as for catalyst regeneration and closed loop fuel control (PD).
IAT: Intake Air Temperature. Some cars use a sensor to read the air coming into the engine to modify fuel delivery strategies, and it can also be used as a back-up or check for the MAF sensor.
EGR: Exhaust Gas Recirculation, a mechanism to lower a specific pollutant, NOx (see below)
NOx: Nitrides of Oxygen, a pollutant formed from high temps and pressure (as inside a combustion chamber) forcing Nitrogen to bond with Oxygen.
SCR: Selective Catalyst Reduction, a mechanism to lower NOx, post combustion, using a urea (DEF, see below) injection system to release the nitrogen-oxygen bond and turn it into water, oxygen, nitrogen
DEF: Diesel Exhaust Fluid
DPF: Diesel Particulate Filter
TDI: Turbo Direct Injection. VAG's name for their newer diesel engines.
SDI: Sauger Direct Injection (may be mispelled). The non-turbo version of the TDI not sold in North America. Sauger means "suck" in German I think.
IDI: InDirect Injection. Refers to VAG's older diesels, pre-TDI (as well as many other makes of diesels before direct injection became commonplace in light duty diesels).
TD: Turbo Diesel.
US-spec TDI Engines:
VE: Vertielerpumpen, denotes style of Bosch diesel injection pump used on all IDI VAG diesels and TDIs through 2003 US cars.
PD: Pumpe Duese, denotes the unit injector diesel injection system used on 2004 through 2006 model year US cars.
CR: Common Rail, denotes the type of diesel injection system used on 2009+ US cars.
1Z: 90hp 1.9L early style used in the 1996 and 1997 Passat Bosch VE equipped
AHU: virtually identical to the 1Z, used in 1997 through early 1999 Jetta Bosch VE equipped
ALH: 90hp 1.9L late style engine, with VNT and Bosch VE injection pump, used in 1998 through 2003 New Beetle, late 1999 through 2003 Golf and Jetta
BEW: 100hp 1.9L "Pumpe Deuse" unit injector engine used in 2004+ New Beetle, 2004+ A4 chassis Golf, 2004 to early 2005 A4 chassis Jetta sedan, 2004 to 2005 Jetta Wagon
BHW: 134/136hp 2.0L PD engine used in 2004 and 2005 Passat
BRM: 100hp 1.9L PD engine used in late 2005 and 2006 Jetta sedan
BKW: 310hp 5.0L PD V10 used in various years of Touareg
CBEA: 140hp 2.0L "Common Rail" engine used in 2009+ Jetta sedan/wagon
CJAA: 140hp 2.0L "Common Rail" engine very similar to the CBEA
CKRA: 140hp 2.0L "Common Rail" engine used on the 2012+ Passat NMS (often inaccurately referred to as the B7, which uses the CFFN engine). Changes made include an air-to-water intercooler and a Borg-Warner BV40 turbo.
CRUA: 150hp CR engine used in 2015 Golf, Golf Sportwagon, Audi A3
CVCA: same as above, used in 2015 Beetle, Jetta sedan, and Passat
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