Engine Controls - System & Component Testing: Other BMW 5 series E39 facelift

DIGITAL MOTOR ELECTRONICS (DME) CONTROL UNIT

Note. Digital Motor Electronics (DME) control unit may also be referred to as Electronic Control Module (ECM).

Ground, Power & Input/Output Circuits

See PIN VOLTAGE CHARTS article to identify DME control unit ground circuits, power circuits and input/output circuits. To identify DME/ECM connector terminals (Scheme 200)- (Scheme 203). See DME CONTROL UNIT LOCATION table.

Scheme 200

Scheme 201

Scheme 202

Scheme 203

Scheme 204

DME CONTROL UNIT LOCATION

SENSORS

For sensor and switch location, see ENGINE SENSORS & SWITCHES table.

ENGINE SENSORS & SWITCHES

Scheme 205

COOLANT TEMPERATURE SENSOR

Coolant temperature sensor decreases in resistance as temperature rises and vice versa. ECM monitors the sensor voltage which varies as temperature changes the resistance value. As temperature rises, resistance through the sensor decreases, voltage drop of the sensor decreases, and input signal voltage also decreases (5-0 volts). Sensor should be tested using DISplus/GT1 multimeter. DISplus/GT1 multimeter ECM input should be 2.250 k/ohms at 68°F (20°C). Gauge input should be 6.7 k/ohms at 68°F (20°C).

CRANKSHAFT POSITION SENSOR

Crankshaft position/RPM sensor should be tested using DISplus/GT1 for power supply, DC voltage, status display, oscilloscope display found under preset measurements, and engine speed sensor signal.

7-Series

1. Evaporative leakage detection is performed on fuel storage system by Tank Leakage Diagnostic Module (DM-TL) pump which contains an integral DC motor that is activated by ECM. ECM monitors pump motor operating current as the measurement for detecting leaks. DM-TL generates a pressure of.29-.43 psi (20-30 mbar) in the fuel tank and evaporative system. Electrical current required for this is calculated by ECM and serves as the indirect value for the tank pressure. The DM-TL carries out a reference measurement before each measurement. This is performed by building up a pressure for 10-15 seconds using an internal orifice of.019" (.5 mm) as a reference and ECM monitors current (20-30 mA) required by pump motor.
2. If a lower pressure is detected in pressure build-up (low current draw) as compared to reference measurement, this indicates a leak in fuel tank/evaporative system. If a higher pressure is detected (higher current draw), the system does not have a leak. The pump also contains an ECM controlled change over valve that is energized closed during a leak diagnosis test. The ECM only initiates a leak diagnosis test every second time the criteria is met. The criteria is as follows: Engine off with ignition off. ECM still in active state or what is known as "follow up mode". (ECM relay energized, ECM and components online for extended period after key off). Prior to engine/ignition switch off condition, vehicle must have been driven for a minimum of 20 minutes. Prior to minimum 20 minute drive, vehicle must have been off a minimum of 5 hours. No faults in ECM for DM-TL/tank venting system. Fuel tank capacity must be between 10-90 percent (safe approximation between 1/4-3/4 of a tank). Ambient air temperature between 19-95°F (-7-35°C). Altitude less than 8202 feet. Battery voltage between 11.5-14.5 volts.
3. When these criteria are satisfied every second time, ECM will start FUEL SYSTEM LEAK DIAGNOSIS TEST. Test will typically be carried out once a day. The following morning, the test will run again.

X5 (6-Cylinder) & E46

The MS42.0 system uses Bosch LSH 25 oxygen sensors. Voltage range is between 0-800 mV.

Z4 & M3

Vehicles use Bosch LSH 25 oxygen sensors, The pre-cat oxygen sensors measure residual oxygen content of exhaust gas. The sensors produce a low voltage (0-1000 mV) proportional to the oxygen content that allows the ECM to monitor the air/fuel ratio.

7-Series (V8)

1. Sensor conductivity is efficient when the oxygen sensor is hot 1382°F (750°C). For this reason, sensor contains a heating element. This reduces warm up time and retains heat during low engine speed when exhaust temperature is cooler. Oxygen sensor heating elements receive power from Integrated Voltage Supply Module (IVM) and ground supply is pulse width modulated by the ECM. Monitored voltage signal is constantly changing due to combustion variations and normal exhaust pulsations. At a value of lambda = 1, pump cell requires approximately 3 milliamps. Oxygen sensor signal voltage is approximately 1.5 volts. Reference cell voltage is approximately 450 millivolts. At a lambda value of less than one (rich), oxygen sensor signal voltage is approximately.3 volt. At a lambda value of greater than one (lean), oxygen sensor signal voltage is approximately 4.3 volts.
2. If necessary, ECM will correct air/fuel ratio by regulating injection time. ECM monitors length of time sensors are operating in lean, rich and rest conditions. Evaluation period of sensors is over a predefined number of oscillation cycles and pump cell amperage.

7-Series (V12)

Bosch LSH 25 oxygen sensors produce a low voltage (0-1000 mV) proportional to the oxygen content exiting the catalytic converters. If exhaust has a lower oxygen content (rich mixture), there will be a large ion migration through the sensor, generating a higher voltage (950 mV). If the exhaust has a higher oxygen content (lean mixture), there will be a small ion migration through the sensor, generating a lower voltage (080 mV).

HOT-FILM AIR MASS SENSOR

Hot-film air mass sensor is non-adjustable. A faulty hot-film air mass sensor can make engine difficult to restart when engine is hot, engine starts then stalls, malfunction indicator light illuminated, or engine starts and runs only with accelerator pedal depressed. Hot-film air mass sensor can be tested with DISplus/GT1, DISplus/GT1 status page, and the DISplus/GT1 oscilloscope which requires taking the measurement with the ECM and the universal adapter connected to the circuit (engine running).

Visually inspect the sensor for damaged, missing or blocked screens. The screens affect air flow calibration. Also inspect sealing rings where sensor inserts in air filter housing and intake boot. Ensure pin connections are tight.

THROTTLE POSITION SENSOR

Throttle position sensor can be tested with BMW DISplus system or DISplus oscilloscope. When using oscilloscope, select from present measurement which requires taking the measurement with the ECM and the universal adapter connected to circuit. (Scheme 206)

Scheme 206

RELAYS

For fuel pump relay, see FUEL DELIVERY under FUEL SYSTEM. For relay location or location of relay box, see RELAY LOCATION table. (Scheme 207)- (Scheme 232).

RELAY LOCATION

Scheme 207

Scheme 208

Scheme 209

Scheme 210

Scheme 211

Scheme 212

Scheme 213

Scheme 214

Scheme 215

Scheme 216

Scheme 217

Scheme 218

Scheme 219

Scheme 220

Scheme 221

Scheme 222

Scheme 223

Scheme 224

Scheme 225

Scheme 226

Scheme 227

Scheme 228

Scheme 229

Scheme 230

Scheme 231

Scheme 232

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES article.

Before any service work is performed on any fuel system related component, always adhere to the following

1. Observe relevant safety legislation pertaining to your area.
2. Ensure adequate ventilation.
3. Use exhaust extraction system where applicable (alleviate fumes).
4. Do not operate the fuel pump unless it is properly installed in the fuel tank and is submersed in the fuel (fuel lubricates the pump).
5. Always wear adequate protection clothing including eye protection.
6. Use caution when working around a hot engine compartment.
7. During fuel system repair that involves "sealing rings" always replace them with new copper rings only.
8. BMW does not recommend any unauthorized modifications to the fuel system. The fuel system is designed to comply with strict federal safety and emissions regulations.
9. Fuel quality should always be considered when diagnosing a driveability complaint. The type of fuel, proper AKI rating, impurities and moisture are not factored by the ECM.

Fuel Pump Relay

Remove fuel pump relay. See RELAY LOCATION table. Apply battery voltage to relay terminals No. 30 and 86. (Scheme 233) Ground relay terminal No. 85. Voltage should now exist at relay terminal No. 87. Replace relay if it does not work as indicated.

Note. If relay does not work on vehicle, check battery feed, DME master (main) relay, DME/Motronic control unit and ground circuits going to fuel pump relay. Only sockets No. 2, 4, 6 and 8 are used by relay.

Fuel Pressure Regulator

As operating mode of engine varies, so does amount of fuel it requires, ranging from low at idle speed to high at full throttle. This requirement is set with the help of pressure regulator. Pressure regulator governs fuel pressure, controlling it between low and high to suit requirements. Fine adjustment of fuel injection quantity is performed using fuel injection period controlled by DME. Vacuum in intake manifold provides load connection for pressure regulation. This vacuum is applied to diaphragm in pressure regulator. At idle speed or when coasting, a vacuum develops in intake pipe. Fuel pressure reduces by this amount, starting from nominal value. Nominal value is embossed in housing of pressure regulator. At full throttle, intake pipe is approximately zero and pressure regulator controls fuel pressure to nominal value embossed on housing.

1. Remove fuel pressure regulator. Note code number and nominal pressure on fuel pressure regulator body. Install BMW Service Tester (133060) with Connecting Hose (133064) in fuel feed left line.
2. Remove fuel pump relay. See «RELAY LOCATION»(ref-151726-S39674954422003010700000) table. Connect jumper wire between relay base terminals No. 30 and 87. Read off fuel injection pressure on pressure gauge.
3. If fuel pressure drops rapidly, seal return line (upper line) with Clamp (133010) and briefly operate fuel pump. If injection pressure in now stable, pressure regulator is defective. If injection pressure drops, check for leak in front of pressure regulator.

Fuel Pressure Check (Lack Of Power)

Run engine at idle and check fuel pressure. See FUEL PRESSURE REGULATOR . Disconnect vacuum hose from fuel pressure regulator, simulating wide open throttle. If fuel pressure does not increase 5.8-10.1 psi (.40-.71 kg/cm 2 ), replace vacuum hose and repeat test. If fuel pressure still does not increase, replace fuel pressure regulator.

Fuel Pressure Check (Hard Start)

1. Run engine at idle then turn off. Note fuel pressure. Note fuel pressure again after 20-30 minutes. If fuel pressure decreases by greater than 7.2 psi (.5 kg/cm 2 ), turn engine on, wait for pressure to stabilize, then turn engine off and immediately clamp off intake line near pressure gauge with Clamp (133010). Note fuel pressure. Read fuel pressure again after 20-30 minutes.
2. If fuel pressure drops by less than 7.2 psi (.5 kg/cm 2 ), check for fault in fuel supply lines, in-tank supply hose, or defective non return valve in fuel pump. If fuel pressure again drops by more than 7.2 psi (.5 kg/cm cm2 ), replace pressure regulator.

Fuel Pressure & Volume

1. To check fuel pressure, install BMW Service Tester or DIS tester with connecting line and "T" Section (13 3 064) in the fuel delivery line between fuel filter and pressure regulator. Fuel in fuel lines is under 44 psi (3 bar). Catch and dispose of escaping fuel. See «FUEL PRESSURE & DELIVERY PERFORMANCE»(ref-151726-S36558070842003010700000) table.
2. Disconnect fuel return line. Attach an extension hose. Place hose in Measuring Glass (133020). Remove fuel pump relay. Apply battery voltage to relay base terminals No. 30 and 87. (Scheme 233) See «FUEL PRESSURE & DELIVERY PERFORMANCE»(ref-151726-S36558070842003010700000) table.

FUEL PRESSURE & DELIVERY PERFORMANCE

Scheme 233

Preliminary Check

1. Injectors should be tested using DISplus/GT1 for resistance, power supply, status display-fuel injection signal, and ECM final stage transistor activation. These test functions are found under the oscilloscope preset list. Install universal adapter, diagnostic cable, negative lead to ECM ground and positive lead to the ground activation circuit for the injector. This test is performed with the engine cranking or running.
2. Fuel supply hardware should be visually inspected for damage that can affect pick-up, transfer, pressure and return. The fuel tank must be drained first before removing the service access cap to perform any repair. The fuel filter, fuel pressure regulator, electric fuel pump, right fuel level sensor and siphon jet are accessed through the service access cap. Remove the single 6-pin electrical connector (2 pins for the fuel pump, 2 for each level sensor-left/right). Remove the fuel supply line by releasing the quick release coupling. Fuel tank is secured by 2 straps to the body.

Fuel Injector

Individual fuel injector resistance should be 15-17 ohms. Injector group resistance should be 7.5-8.5 ohms for V8 and V12 (each bank) and 5-6 ohms for 6-cylinder engine.

Fuel Injector Leakage

1. Remove fuel injectors. Mark sequence of injector valves relative to cylinders on each injector valve. Clip injector valves into Holding Fixture (13 6 205). Connect special tool to injector valves. Connect Harness (13 6 206) to a 12-volt battery. This removes the remaining fuel from the injector valves. Lay a clean cloth under injector valves to catch remaining fuel. Connect holding fixture to compressed air connection at maximum 43 psi (3 bar). Residual fuel is now blown out of the injector valves. CAUTION: Carry out leak test only after remaining fuel has been blown out of injector valves.
2. Separate harness from injector valves. Install injector valves with holding fixture in a container with hot water at 140-176°F (60-80°C). Regulate air pressure at connection No. 1 on holding fixture to 44 psi. Note volume of air emerging. Permitted volume of air emerging is 2 air bubbles per injector valve within a 15-second period. Injector valves with larger amounts of air emerging must be cleaned. Remove injector valves from water and dry with compressed air.

Fuel Injector Cleaning

1. Remove fuel injectors. Install injector valves in Holding Fixture (13 6 205). (Scheme 234) Connect Harness (13 6 206) to injector valves and to a 12-volt battery. This removes remaining fuel from injector valves. Lay a clean cloth under injector valves to catch remaining fuel. Connect holding fixture to compressed air connection (maximum 44 psi). (Scheme 235) Residual fuel is now blown out of injector valves.
2. Separate Harness (13 6 206) from injector valves. Install injectors with holding fixture in a container with hot water at 140-176°F (60-80°C). (Scheme 236) Regulate air pressure at connection on holding fixture to 44 psi. Note volume of air emerging from injectors. Permitted volume of air emerging from each injector is 2 air bubbles per injector within a 15-minute period. Injectors with a larger amount of air must be cleaned. Remove injectors from water and dry well with compressed air.
3. Use Ultrasonic Cleaning Unit (13 6 200) to clean injector valves. Attach injector valves to cleaning unit with holding fixture. Fill cleaning unit with Cleaning Concentrate (13 6 207). (Scheme 236) Perform cleaning procedure as specified by manufacturer. Perform leak test on cleaned injector valves. See «FUEL INJECTOR LEAKAGE»(ref-151726-S34512600502003010700000). CAUTION: Do not carry out leak test in cleaning concentrate but rather in a water bath.
4. To remove preserving agent, rinse new injector valves with fuel only after about 5 minutes. Install injector valves immediately in engine and run engine. This flushes out any remaining cleaning concentrate, preventing injector valve corrosion. Due to the risk of corrosion, cleaned injector valves cannot be stored.

Scheme 234

Scheme 235

Scheme 236

IDLE AIR ACTUATOR VALVE

Idle air actuator valve and air circuit (passage ways) should be checked for physical obstructions. Visually inspect the sealing gasket, mounting bracket and air hose clamps. Resistance of the valve winding should be checked. ECM output and idle speed control valve operation can be tested by COMPONENT ACTIVATION on DISplus/GT1. Pulse width modulation ground outputs from the ECM can be tested using the DISplus/GT1 oscilloscope. If valve is blocked or contaminated, a fault code can also be present. See IDLE AIR ACTUATOR VALVE LOCATION table. Valve is either a 2-pin or 3-pin type. (Scheme 237)and (Scheme 238).

Scheme 237

Scheme 238

IDLE AIR ACTUATOR VALVE LOCATION

IGNITION SYSTEM

Note. For basic ignition checks and oscilloscope pattern diagnosis, see BASIC DIAGNOSTIC PROCEDURES article.

Ignition Coil Resistance

Measure primary coil resistance between terminal No. 1 and terminal No. 15. (Scheme 239) Secondary coil resistance cannot be measured. See IGNITION COIL RESISTANCE table.

Scheme 239

Scheme 240

1. Select cylinder mode on BMW SERVICE TESTER (Sun 2013 Engine Analyzer). Connect universal adapter lead on tester. Connect Brown lead to known good engine ground. (Scheme 240) Connect Black lead to terminal No. 1 on Adapter (127020).
2. Connect adapter to ignition coil of cylinder being tested. Red lead is not used as only one cylinder can be measured. Engine speed displayed will be reduced by a factor of 4. Produce stopped signal on oscilloscope by pressing "R" button on tester. Combustion voltage line will be very erratic on oscilloscope pattern (this is normal).

Ignition Voltage Too High

Check for excessive spark plug electrode gap, high compression, lean air/fuel mixture, low electrode temperature, or burnt spark plug electrode.

Ignition Voltage Too Low

Check for insufficient spark plug electrode gap, low compression, or high electrode temperature.

Ignition Coil

Measure primary coil resistance between terminal No. 1 and terminal No. 15. see scheme 48 Secondary coil resistance cannot be measured. See IGNITION COIL RESISTANCE table.

IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C)

Ignition Coil Secondary Signal Check

1. Connect engine analyzer and Adapter (127020) as described in «IGNITION COIL PRIMARY SIGNAL CHECK»(ref-151726-S35876681502003010700000). Remove ignition coil. Connect a spark plug wire (between coil and spark plug) to cylinder being tested. Connect inductive pickup Blue lead, on lead to cylinder being tested. (Scheme 241)
2. Produce stopped signal on oscilloscope by pressing "R" button on tester. Display of ignition signal on oscilloscope will be strongest when inductive clip and Black lead are connected to same cylinder. Display on oscilloscope may be disturbed by neighboring ignition leads (this is normal).

Scheme 241

Scheme 242

Scheme 243

1. Set pressure regulator on Tester (16 1 171) fully in "-" direction. Connect tester via compressed air line to workshop/garage compressed air system with a pressure of 116-145 psi. Connect pressure sensor of BMW Diagnosis and Information System (DIS) with a measuring range of 0-50 psi (0-3.5 bar). Select Adapter (16 1 172 or 16 1 173) matching vehicle's filler cap and attach to quick-release coupling of tester. (Scheme 242)and (Scheme 243).
2. Install filler cap on appropriate adapter. Only the absolute pressure is indicated in the display of the DIS. The current ambient air pressure is already displayed without additional pressurization.
3. Ensure testing equipment is okay by checking testing equipment for leaks. Select MEASUREMENT function on DIS. Increase pressure by 2.9 psi (.2 bar) with pressure regulator on tester. Using Hose Clip (13 3 010), disconnect delivery line from tester to fuel filler neck. Wait 60 seconds. Read off final pressure value and compare with starting pressure value. If pressure drop is greater than.174 psi (.012 bar) testing equipment is leaking. Check connection joints for leaks.
4. Check filler cap pressure relief valve by following same test procedure for checking testing equipment for leaks in step 3. Increase pressure by 4.3 psi (.3 bar) with pressure regulator on adapter. If pressure drop is greater than.174 psi (.012 bar), filler cap pressure relief valve is faulty. Replace filler cap.

Fuel Tank Vent (Evaporation) Control Valve

For location of fuel tank vent (evaporation) control valve on models where this information is available, see FUEL EVAPORATION CONTROL VALVE LOCATION table.

FUEL EVAPORATION CONTROL VALVE LOCATION

FUEL TANK LEAKAGE

Note. If a leak in the tank ventilation system is indicated by CHECK ENGINE light in instrument cluster lighting up, a leak test must be carried out. Fault memory of DME control unit must be read out using BMW or generic scan tool. If sensors are okay, then begin leak test. Ensure following conditions are observed to obtain plausible measuring results: Contents of fuel tank: 25-75% full. Park vehicle at least 2 hours before test so fuel temperature is approximately that of ambient temperature. Ideal fuel temperature is approximately 50-68°F (10-20°C). Never refuel vehicle directly prior to leak test due to strong emission of gas by fresh fuel.