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Contents Wiring diagrams Section: Ignition System All sections

Ignition/glow Plug System - 3.7l & 4.2l v8 (aew, Abz) Audi A8 D2

Ignition System 33 illustrations ~2803 words

Safety precautions

WARNINGBe alert when working on or near the engine. High ignition secondary voltage can cause serious personal injury and damage vehicle components. DO NOT touch or disconnect ignition wiring when the engine is running or being turned at starter speed. DO NOT operate the starter if fuel injectors are removed. Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine control module may be damaged. The ignition must be switched off before connecting or disconnecting injection or ignition system wiring or tester cables. In order to run the engine at starting speed without actually starting it (e.g. to test compression), disconnect the connectors from the output stages of the ignition coils and from all the fuel injectors. After completing the work, check and erase the DTC memory. If DTC memory was erased generate readiness code . The ignition must always be switched off when cleaning the engine.
WARNINGBEFORE cranking the engine at starting RPM (as for compression test) disable ignition and fuel injection systems: Disconnect both ignition coil power output stages, and both fuses for Motronic in the E-box in the plenum. After the work is completed, erase Diagnostic Trouble Code (DTC) memory, and carry out component functional checks using "Output Diagnostic Test Mode" function 03. If necessary, correct any malfunctions, erase DTC memory and generate new readiness code.
CAUTIONBefore disconnecting the battery: Stop the engine. Be sure the ignition is switched OFF (also applies when connecting the battery). Failure to do so may damage the Engine Control Module (ECM). Be sure of proper radio code (for vehicles equipped with coded anti-theft radio). When connecting and disconnecting electrical test equipment (LED voltage tester, multi meter, etc.): Be sure the ignition is switched OFF. Use correct adapters from VAG1594 connector test kit Be sure the battery negative (-) cable is disconnected, when: Working on the electrical system Resistance (spot) welding or electric arc welding anywhere on the vehicle. When connecting and disconnecting electrical test equipment (LED voltage tester, multimeter, etc.): Be sure the ignition is switched OFF. Use correct adapters from the VW 1594 connector test kit.
CAUTIONFor any work affecting the Engine Control Module (ECM): BEFORE disconnecting the ECM harness connector, switch the ignition OFF and WAIT at least 20 seconds. Failure to do so may damage the ECM. DO NOT connect any outside voltage source to stimulate an output signal at the ECM.

Technical data

Engine codeABZ/AEW
RPM limit (Motronic)6300 +/- 40 RPM
Engine idle speedMaintained by Idle Air Control (IAC), (cannot be adjusted)
Ignition systemSingle-coil system with 8 ignition coils (combined coil and power output stage) located above spark plug connectors and installed directly on spark plugs
Firing order1-5-4-8-6-3-7-2
Engine speed (RPM) sensor resistanceApprox. 1.0 k ohms
Ignition coilsIndividual coils controlled by two power output stages
Ignition timingDetermined by Motronic Engine Control Module (ECM), (cannot be adjusted)

TECHNICAL DATA

Misfire recognition, checking

  1. Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle). See «VAG1551 OR VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Indicated on display

VAG1551 Scan Tool Display - Checking Misfire Recognition (1 Of 4). Scheme 113

Scheme 113: VAG1551 Scan Tool Display - Checking Misfire Recognition (1 Of 4)
Scheme 113: VAG1551 Scan Tool Display - Checking Misfire Recognition (1 Of 4)
  1. Press buttons -0- and -8- to select "Read Measuring Value Block" (scan tool function 08), and press -Q- button to confirm input.

Indicated on display

VAG1551 Scan Tool Display - Checking Misfire Recognition (2 Of 4). Scheme 114

Scheme 114: VAG1551 Scan Tool Display - Checking Misfire Recognition (2 Of 4)
Scheme 114: VAG1551 Scan Tool Display - Checking Misfire Recognition (2 Of 4)
  1. Press buttons -0-, -1 - and -8- to input display group number 18 (018), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)

VAG1551 Scan Tool Display - Checking Misfire Recognition (3 Of 4). Scheme 115

Scheme 115: VAG1551 Scan Tool Display - Checking Misfire Recognition (3 Of 4)
Scheme 115: VAG1551 Scan Tool Display - Checking Misfire Recognition (3 Of 4)

Scheme 116

Scheme 116
Scheme 116
  1. Check specified values for misfire recognition (display fields 1-4). (Scheme 116) (Scheme 116): Display Group 18: Misfire Recognition
  2. Press -3- button to advance to display group 19.

Indicated on display

VAG1551 Scan Tool Display - Checking Misfire Recognition (4 Of 4). Scheme 117

Scheme 117: VAG1551 Scan Tool Display - Checking Misfire Recognition (4 Of 4)
Scheme 117: VAG1551 Scan Tool Display - Checking Misfire Recognition (4 Of 4)

Scheme 118

Scheme 118
Scheme 118

Scheme 119

Scheme 119
Scheme 119
  1. Check specified values for misfire recognition for bank 1 (display fields 1-4): (Scheme 118): Display Group 19: Misfire Recognition, Bank 1 If displayed values are not as specified in (Scheme 118), continue with test. Notes on display groups 19 and 20: These display groups indicate the number of misfires for each cylinder during the current interval of 1000 crankshaft revolutions. If misfiring is recognized for specific combinations of cylinders, 1-4-6-7 or 2-3-5-8, then the ignition coil power output stage for those cylinders is faulty.
  2. Press -3- button to advance to display group 20.
  3. Check specified values for misfire recognition for bank 2 (display fields 1-4): (Scheme 119): Display Group 20: Misfire Recognition, Bank 2 If displayed values are not as specified in (Scheme 119), continue with test. Notes on display groups 19 and 20: These display groups indicate the number of misfires for each cylinder during the current interval of 1000 crankshaft revolutions. If misfiring is recognized for specific combinations of cylinders, 1-4-6-7 or 2-3-5-8, then the ignition coil power output stage for those cylinders is faulty.
  4. Press --> button to advance program sequence.
  5. Press buttons -0- and -6- to select "End Output" (scan tool function 06), and press -Q-button to confirm input.

If displayed values in display groups 19 and 20 are outside the specified range

  1. Check fuel level (too low)
  2. Check spark plugs
  3. Check fuel injectors. See «FUEL INJECTORS, CHECKING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz) .
  4. Check fuel injection volume. See «FUEL INJECTION VOLUME, FUEL INJECTOR LEAKAGE AND SPRAY PATTERN, CHECKING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz) .
  5. Check ignition coils. See «IGNITION COILS, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz) .
  6. Check power output stages. See «IGNITION COIL POWER OUTPUT STAGES, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz) .
  7. Check for mechanical malfunction

Scheme 120

Scheme 120: Checking primary connections and voltage supply
Scheme 120: Checking primary connections and voltage supply
  1. Fuses for ignition coils OK (located in E-box in plenum) (Scheme 120): Removing Bracket Along With Ignition Coil Power Output
  2. Remove bracket along with ignition coil power output stages -N122- and -N192-.
  3. Disconnect both 4-pin harness connectors.
  4. Switch ignition on.
  5. Connect one lead of VAG1527B LED voltage tester to engine Ground. Connect other lead in sequence to check for voltage at each pin of both 4-pin connectors.

LED must light up for all 8 terminals.

Note. The measurement is the voltage supply through the primary circuit of the applicable ignition coil to the power output stage.

If LED does not light for one terminal

Scheme 121

Scheme 121
Scheme 121
  1. Disconnect 3-pin harness connector from applicable ignition coil. see scheme 10: Identifying Ignition Coil Harness Connector Terminals
  2. Check wiring for open circuit between power output stage and ignition coil connector terminal 1. WIRING BETWEEN POWER OUTPUT STAGE AND IGNITION COIL Power output stage 4-pin connector terminal Ignition coil 3-pin connector terminal 1 Black connector Cylinder 1 1 2 4 3 6 4 7 Brown connector Cylinder 1 2 2 3 3 5 4 8

If wiring is OK

Identifying Ignition Coil Harness Connector Terminals. Scheme 122

Scheme 122: Identifying Ignition Coil Harness Connector Terminals
Scheme 122: Identifying Ignition Coil Harness Connector Terminals
  1. Check wiring for open or short circuit between ignition coil connector terminal 15 and fuse (E-box in plenum).
  2. Check voltage supply to fuse (open circuit).

If wiring is OK

  1. Check ignition secondary circuit. See «CHECKING IGNITION COIL SECONDARY CIRCUIT»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz__checking-ignition-coil-secondary-circuit) .

Note. Measuring ignition coil primary resistance is usually not necessary with this test (primary resistance is approx. 0.3-0.5 ohm, measured between ignition coil terminals 1 and 15). A high-tension isolation diode is integrated in the ignition coil secondary circuit. It is therefore not possible to measure ignition coil secondary resistance with conventional test equipment.

Checking ignition coil secondary circuit

  1. Connect multimeter US 1119 (Fluke 83 or equivalent) and check for open circuit between 3-pin connector terminal 4A and engine Ground.

Identifying Ignition Coil Harness Connector Terminals. Scheme 123

Scheme 123: Identifying Ignition Coil Harness Connector Terminals
Scheme 123: Identifying Ignition Coil Harness Connector Terminals

If all Ground connections are OK

  1. Replace ignition coils.
  2. Generate readiness code. See «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Scheme 124

Scheme 124
Scheme 124
  1. Remove bracket along with ignition coil power output stages -N122- and -N192- (arrows). (Scheme 124): Removing Bracket Along With Ignition Coil Power Output Stages -N122- And -N192
  2. Disconnect all fuel injector harness connectors and hold-downs.
  3. Disconnect 5-pin connectors (from ECM) from both power output stages.
  4. Connect one lead of VAG1527B LED voltage tester to engine Ground. Connect other lead in sequence to check for voltage at terminals 1, 2,4 and 5 of each 5-pin connector. (Scheme 125): Identifying Ignition Coil Power Output Stage Connector Terminals

For each test (at each connector terminal)

  1. Briefly operate starter motor. LED must flash each time.

If LED does not flash

Scheme 125

Scheme 125
Scheme 125
  1. Connect VAG1598/19 test box to Engine Control Module (ECM) harness connector. See «VAG1598/19 TEST BOX, CONNECTING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz__vag159819-test-box-connecting). see scheme 15: Identifying Ignition Coil Power Output Stage Connector Terminals
  2. Check wiring for open circuit, short to B+ or short to Ground between power output stage harness connector and ECM. IGNITION COIL POWER OUTPUT STAGE CIRCUIT TEST Power output stage 5-pin connector terminal VAG1598/1 9 test box socket (ECM terminal) Black (-N122-) 1 B8 2 B7 4 B6 5 B5 Brown (-N192-) 1 B14 2 B13 4 B15 5 B16

If wiring between power output stage and ECM is OK

Exploded View Of ECM Connectors. Scheme 126

Scheme 126: Exploded View Of ECM Connectors
Scheme 126: Exploded View Of ECM Connectors
  1. Check wiring (Ground connection) for continuity between terminal 3 of each 5-pin connector and engine Ground. (Scheme 127): Identifying Ignition Coil Power Output Stage Connector Terminals

If wiring and connections are OK

  1. Replace ECM ( «MOTRONIC MULTIPORT FUEL INJECTION (MFI) SYSTEM, SERVICING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz) ) and generate new readiness code ( «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) ).

Checking power output stage function

  1. Both 5-pin connectors remain connected.
  1. Disconnect both 4-pin harness connectors from ignition coil power output stages.
  2. Connect VAG1527B LED voltage tester between B+ (for example, one ignition coil terminal 15) and one terminal at 4-pin power output stage connector.

Note. LED tester will light dimly to indicate very low voltage while the engine is not running, then become brighter (flashing) during engine cranking.

For each test (at each connector terminal)

  1. Briefly operate starter motor. LED must flash.

If LED does not flash at one or more terminals

  1. Replace power output stage.
  2. Check readiness code. See «READINESS CODE, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) . If Diagnostic Trouble Code (DTC) memory has been erased, then generate new readiness code. See «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Test conditions

  1. Fuse for fuel injectors OK (E-box in plenum)
  2. Motronic Engine Control Module (ECM) power supply relay -J271 -OK. See «MOTRONIC ECM POWER SUPPLY RELAY, CHECKING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz__motronic-ecm-power-supply-relay-checking) .

Scheme 127

Scheme 127: Checking
Scheme 127: Checking
  1. Connect VAG 1598/19 test box to Engine Control Module (ECM) harness connector. See «VAG1598/19 TEST BOX, CONNECTING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz__vag159819-test-box-connecting).
  2. Connect VAG1527B LED voltage tester between ECM/test box socket D9 (permanent B+) and, one after the other in sequence, test box sockets D11, E7, E11 and E12 (Ground connections). see scheme 18: Identifying ECM Connectors LED must light up in each case.

If LED does not light

  1. Check wiring and connections for open circuit and repair as necessary.
  2. Connect VAG1527B LED voltage tester between ECM/test box sockets E7 (Ground) and B3 (Ignition, +, terminal 15).
  3. Switch ignition on. LED must light up.
  4. Switch ignition off.

If LED does not light

  1. Check wiring and connections for open circuit and repair as necessary.

Knock control, checking

  1. Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle). See «VAG1551 OR VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Indicated on display

VAG1551 Tool Display - Knock Control (1 Of 3). Scheme 128

Scheme 128: VAG1551 Tool Display - Knock Control (1 Of 3)
Scheme 128: VAG1551 Tool Display - Knock Control (1 Of 3)
  1. Press buttons -0- and -8- to select "Read Measuring Value Block" (scan tool function 08), and press -Q- button to confirm input.

Indicated on display

VAG1551 Tool Display - Knock Control (2 Of 3). Scheme 129

Scheme 129: VAG1551 Tool Display - Knock Control (2 Of 3)
Scheme 129: VAG1551 Tool Display - Knock Control (2 Of 3)
  1. Press buttons -0-, -1 - and -3- to input display group number 13 (013), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)

VAG1551 Tool Display - Knock Control (3 Of 3). Scheme 130

Scheme 130: VAG1551 Tool Display - Knock Control (3 Of 3)
Scheme 130: VAG1551 Tool Display - Knock Control (3 Of 3)
  1. Check specified values for knock control for bank 1 (display fields 1-4). see scheme 22
  2. Road test. WARNING: When driving or riding in an airbag-equipped vehicle, NEVER hold the scan tool or other test equipment in your hands or lap while in motion. Objects between you and the airbag increase the risk of injury in an accident. During a test drive in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician. see scheme 22: Display Group 13: Knock Control, Bank 1 (Vehicle In Operation) If displayed values are not as specified in see scheme 22, see «CHECKING KNOCK SENSORS»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz).
  3. Press -3- button to advance to display group 14.
  4. Check specified values for knock control for bank 2 (display fields 1-4). (Scheme 131)

Display Group 14: Knock Control, Bank 2 (Vehicle In Operation). Scheme 131

Scheme 131: Display Group 14: Knock Control, Bank 2 (Vehicle In Operation)
Scheme 131: Display Group 14: Knock Control, Bank 2 (Vehicle In Operation)

If displayed values are not as specified in (Scheme 131), see CHECKING KNOCK SENSORS.

Notes on knock control

  1. Temporary fluctuations of 12° (crankshaft) are OK.
  2. Knock control is active throughout the entire RPM range, starting at engine loads greater than 30%. When engine load exceeds 30% the actual timing retardation values are indicated. see scheme 24: Evaluating Display Groups 13 And 14
  3. Press -3- button to advance to display group 15.

Knock sensors, checking

Note. Knock Sensor (KS) 1 -G61- and Knock Sensor (KS) 2 -G66- cannot be checked electrically. Use only gold-plated terminals for repair of knock sensor connector terminals. To function correctly, it is important that the knock sensor tightening torque of 20 Nm (15 ft lb) be maintained. When troubleshooting, check the knock sensor harness connector terminals for corrosion.

  1. Connect VAG1551 or VAG1552 Scan Tool (ST) and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle). See «VAG1551 OR VAG1552 SCAN TOOL (ST), CONNECTING AND SELECTING "ENGINE ELECTRONICS" ADDRESS WORD 01»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Indicated on display

VAG1551 Tool Display - Knock Control (1 Of 3). Scheme 132

Scheme 132: VAG1551 Tool Display - Knock Control (1 Of 3)
Scheme 132: VAG1551 Tool Display - Knock Control (1 Of 3)
  1. Press buttons -0- and -8- to select "Read Measuring Value Block" (scan tool function 08), and press -Q- button to confirm input.

Indicated on display

  1. Press buttons -0-, -1 - and -5- to input display group number 15 (015), and press -Q- button to confirm input.

Indicated on display

VAG1551 Tool Display - Knock Control (3 Of 3). Scheme 133

Scheme 133: VAG1551 Tool Display - Knock Control (3 Of 3)
Scheme 133: VAG1551 Tool Display - Knock Control (3 Of 3)

Scheme 134

Scheme 134
Scheme 134
  1. Check specified values for knock control for bank 1 (display fields 1-4). (Scheme 135) Engine speed for test: 3300 RPM (Scheme 135): Display Group 15: Knock Control, Bank 1, Testing At 3300 RPM If displayed values are not as specified in (Scheme 135), go to «CHECKING KNOCK SENSORS»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz). Note on display groups 15 and 16: At higher RPM, knock sensor signal voltage can reach up to approx. 35 volts.
  2. Press -3- button to advance to display group 16.
  3. Check specified values for knock control for bank 2 (display fields 1-4): Engine speed for test: 3300 RPM (Scheme 136): Display Group 16: Knock Control, Bank 2, Testing At 3300 RPM If displayed values are not as specified in (Scheme 136), go to «CHECKING KNOCK SENSORS»(/audi/a8/d2-1994-1999/remont/ignition-system/#ignitionglow-plug-system-37l-42l-v8-aew-abz). Note on display groups 15 and 16: At higher RPM, knock sensor signal voltage can reach up to approx. 35 volts.
  4. Press --> button to advance program sequence.
  5. Press buttons -0- and -6- to select "End Output" (scan tool function 06), and press -Q button to confirm input.

Scheme 135

Scheme 135: Checking knock sensors
Scheme 135: Checking knock sensors
  1. Disconnect applicable knock sensor harness connector (near fuel rail under center engine cover).
  2. Connect multimeter US 1119 (Fluke 83 or equivalent) and check for short circuits between knock sensor connector terminals. There must be no continuity between any of the 3 terminals. (Scheme 137): Identifying Knock Sensor Connector Terminals

If there are no short circuits, but knock sensor signal is faulty

  1. Check readiness code. See «READINESS CODE, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) . If Diagnostic Trouble Code (DTC) memory has been erased, then generate new readiness code. See «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Scheme 136

Scheme 136: Checking wiring between knock sensors and ECM
Scheme 136: Checking wiring between knock sensors and ECM

Scheme 137

Scheme 137
Scheme 137
  1. Connect VAG1598/19 test box to Engine Control Module (ECM) harness connector. See «VAG1598/19 TEST BOX, CONNECTING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz__vag159819-test-box-connecting). (Scheme 138): Identifying Knock Sensor Harness Connector Terminals
  2. Check wiring for open circuit, short circuit to short circuit to Ground between applicable knock sensor harness connector and ECM. (Scheme 139): Identifying ECM Connectors KNOCK SENSOR CIRCUIT TEST: 1 -G61- (CYL. 1-4) Knock sensor harness connector terminal VAG1598/19 test box socket (ECM terminal) 1 A20 2 A19 3 D11 KNOCK SENSOR CIRCUIT TEST: 2 -G66- (CYL. 5-8) Knock sensor harness connector terminal VAG1 598/1 9 test box socket (ECM terminal) 1 A21 2 A19 3 D11

If there are no open or short circuits

  1. Replace knock sensor.
  2. Check readiness code. See «READINESS CODE, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) . If Diagnostic Trouble Code (DTC) memory has been erased, then generate new readiness code. See «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

Camshaft Position (CMP) sensor, checking

The Camshaft Position (CMP) sensor -G40- is located on the rear of the left cylinder head. See COMPONENT LOCATIONS, OVERVIEW .

Note. During normal engine operation the ECM, using the CMP sensor signal, recognizes the ignition point for cylinder 1 and initiates ignition for each cylinder at every second crankshaft revolution. The engine will start or run with a faulty or disconnected CMP sensor, since the ECM initiates ignition for each cylinder with ever crankshaft revolution after recognizing the malfunction. For the fuel injection, being off by one crankshaft revolution has no noticeable effect. Fuel is injected against the closed intake instead of taking place while the valve is open. The quality of the fuel/air mixture is not significantly affected.

Scheme 138

Scheme 138: Checking CMP sensor signal
Scheme 138: Checking CMP sensor signal
  1. Push back protective rubber boot at back of sensor harness connector (CMP sensor remains connected).
  2. Connect VAG1527B LED voltage tester bet connector terminals 1 and 2 (from the back). (Scheme 140): Identifying CMP Sensor Harness Connector Terminals NOTE: Harness connector terminals are numbered on back side of the connector.
  3. Briefly operate starter motor. LED must flash.

If LED does not flash

  1. Check CMP sensor power supply.

Checking CMP sensor power supply

  1. Disconnect CMP sensor harness connector.
  2. Switch ignition on.
  3. Connect multimeter US 1119 (Fluke 83 or equivalent) between CMP connector terminal 1 and engine Ground. Specified value: 4.5-5.5 volts

Checking CMP sensor signal wiring

  1. Connect multimeter US 1119 (Fluke 83 or equivalent) between CMP connector terminal 2 and engine Ground.
  2. Switch ignition on. Specified values: Battery Positive Voltage (B+)
  3. Switch ignition off.

Checking CMP sensor Ground connection

  1. Connect multimeter US 1119 (Fluke 83 or equivalent) and check resistance between C sensor connector terminal 3 and engine Ground. Specified value: Continuity

If there is not continuity, and the LED does not flash

  1. Replace CMP sensor.
  2. Check readiness code. See «READINESS CODE, CHECKING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) . If Diagnostic Trouble Code (DTC) memory has been erased, then generate new readiness code. See «READINESS CODE, GENERATING»(/audi/a8/d2-1994-1999/remont/ignition-system/#on-board-diagnostic-obd-37l-42l-v8-aew-abz) .

If one of the specified values was not obtained

Scheme 139

Scheme 139
Scheme 139

Scheme 140

Scheme 140
Scheme 140
  1. Connect VAG1598/19 test box to Engine Control Module (ECM) harness connector. See «VAG1598/19 TEST BOX, CONNECTING»(/audi/a8/d2-1994-1999/remont/fuel-system/#multiport-fuel-injection-mfi-37l-42l-v8-4v-aew-abz__vag159819-test-box-connecting). see scheme 34: Identifying Knock Sensor Harness Connector Terminals
  2. Check wiring for open circuit, short circuit to B+ or short to Ground between CMP sensor and ECM. KNOCK SENSOR CIRCUIT TEST CMP sensor connector terminal VAG1598/19SOC (ECM terminal] 1 A3 (+5 volts) 2 B2 (signal) 3 D12 (Ground) see scheme 35: Identifying ECM Connectors

If, after erasing Diagnostic Trouble Code (DTC memory, CMP sensor malfunctions are still stored and all test results to this point have been OK

  1. Remove CMP sensor.
  2. Make sure that trigger wheel is correctly installed. (Can be damaged if mounting bolts are incorrectly torqued).

If CMP sensor trigger wheel is OK

  1. Check camshaft drive belt adjustment. See «INSTALLING AND ADJUSTING TENSION»(ref-196861-S05766242572005100900000) .

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