Page 1 of 7 Volkswagen > A4 Platform > 1999-2005 1.9 Liter 4-Cyl. 2V TDI and TDI PD Generic Scan Tool, Engine Code(s): ALH, BEW 26 - Exhaust system, Emission controls Exhaust Gas Recirculation (EGR) system EGR Vacuum Regulator Solenoid Valve, checking Note: Use only gold-plated terminals when servicing terminals in harness connector. Recommended special tools and equipment V.A.G1526 multimeter or V.A.G1715 multimeter V.A.G1594 connector test kit Wiring diagram Test requirements The respective fuses of Diesel-Direct fuel injection system must be OK: => Electrical Wiring Diagrams, Troubleshooting & Component Locations Battery voltage must be at least 11.5 volts. All electrical consumers such as, lights and rear window defroster must be switched off. For vehicles with automatic transmission, selector lever must be in -P- or -N-. Ground (GND) connections between engine and chassis must be OK.
Page 2 of 7 If vehicle is equipped with an A/C system, it must be switched off. No leaks on intake side and exhaust side. Vacuum hoses must be properly sealed. Ignition is switched off. EGR Vacuum Regulator Solenoid Valve -N18- with Potentiometer for EGR -G212- must be OK mechanically and clean, check => page 26-14, removing and installing EGR system components (only vehicles with engine code BEW). Check EGR Vacuum Regulator Solenoid Valve: Vehicles with engine code ALH => page 26-25, Vehicles with engine code BEW => page 26-28. Vehicles with engine code ALH Disconnect connector at solenoid valve for Exhaust Gas Recirculation (EGR). Measure resistance between terminals of valve.
Page 3 of 7 Specified value: 14 to 20 Ω Note: Resistance at room temperature is in lower specified range, resistance at operating temperature is in upper specified range. If specified value is not obtained: Replace EGR Vacuum Regulator Solenoid Valve -N18- => page 26-16, item 4. Erase DTC memory of control module for Diesel-Direct fuel injection system => page ST-26, Diagnostic mode 4: Reset/erase diagnostic data. If specified value is obtained: Switch ignition on. Measure voltage supply of valve at connector terminal 1 and at engine Ground (GND). Specified value: approx. battery voltage Switch ignition off. If specified value is not obtained: Check wires to Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) according to wiring diagram => page 26-27. Check wires to control module Connect test box to wiring harness of Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- => page ST-9, connect test box for wiring test.
Page 4 of 7 Vehicles with 80-pin control module Check for open circuits in wires between test box and harness connector according to wiring diagram. Terminal 1 + socket 2 + 28 Terminal 2 + socket 29 Wire resistance: max. 1.5 Ω Vehicles with 121-pin control module Check for open circuits in wires between test box and connector according to wiring diagram. Terminal 1 + socket 1 and 2 Terminal 2 + socket 61 Wire resistance: max. 1.5 Ω
Page 5 of 7 Check wires for short circuit to each other, to vehicle Ground (GND) and to B+. Specified value: Ω If no malfunctions are found in wires: Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- => page 23-130. Vehicles with engine code BEW Disconnect 6-pin connector from EGR Vacuum Regulator Solenoid Valve -N18- with Potentiometer for EGR -G212-. Check resistance of EGR Vacuum Regulator Solenoid Valve -N18- at terminals 2 + 6. Specified value: 4.0 to 8.0 Ω If specified value is not obtained:
Page 6 of 7 Replace EGR Vacuum Regulator Solenoid Valve -N18- with Potentiometer for EGR - G212- => page 26-14, item 6. Erase DTC memory of control module for Diesel-Direct fuel injection system => page ST-26, Diagnostic mode 4: Reset/erase diagnostic data. Perform a basic setting of EGR Vacuum Regulator Solenoid Valve -N18- with Potentiometer for EGR -G212- => page 26-20. If specified value is obtained: Check wires to Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- according to wiring diagram => page 26-29. Check wires to control module Connect test box (1598/42) to Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- wiring harness using adapter cable (V.A.G 1598/39-1) => page ST-9, connecting test box for wiring test. Check wires between test box and connector for open circuit according to wiring diagram. Terminal 2 + socket 49 Terminal 6 + socket 50 Wire resistance: max. 1.5 Ω Check wires for short circuit to each other, to vehicle Ground (GND) and to B+. Specified value: Ω
Page 7 of 7 If no malfunctions are found in wires: Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- => page 23-130.