Scope and identification
Bosch illustrates several EDC15 systems using different injection hardware. The descriptions below explain those examples; the ECU suffix alone does not identify the exact pump, injector, wiring or calibration fitted to a vehicle. Record the engine, ECU part and software numbers and identify the hardware before applying a definition or diagnostic procedure. Bosch, Electronic Diesel Control, printed pages 15–18.
- EDC15V example: a port-and-helix-controlled VE distributor pump. An actuator moves the metering collar and a position sensor reports its position; a separate timing-device valve influences injection timing.
- EDC15M example: a solenoid-controlled distributor pump such as an axial-piston VP30 or radial-piston VP44. The high-pressure metering valve and timing device are controlled electronically; some arrangements have a separate engine ECU and pump ECU.
- EDC15P example: electronically controlled unit injectors, each combining pumping and injection at its cylinder. Solenoid control and mechanically generated pressure distinguish this system from common rail.
- EDC15C/MS 6.3 example: a common-rail layout with a rail-pressure sensor, pressure-control valve and electrically operated injectors. Fuel pressure and injection commands are separate parts of the control problem.
The descriptions are examples from Bosch’s 2001 overview, not a complete suffix or fitment catalogue. Optional sensors, actuator arrangements and functions vary. Bosch, printed pages 15–18.
Distributor-pump metering and timing
In Bosch’s VE-EDC example, a moving-magnet quantity actuator positions the pump’s control collar. A Hall-based position sensor reports actuator movement to the ECU; engine speed and the position signal contribute to quantity control. The timing-device solenoid modulates pressure acting on the pump’s timing piston. The arrangement also has an electrical shut-off valve as an additional fuel shut-off path. Bosch, printed pages 64–65.
For the illustrated VP30/VP44 arrangements, the pump ECU drives the high-pressure fuel-metering and timing valves in response to engine-management demands. Bosch also describes a later PSG16 arrangement combining pump and engine-control functions at the pump. A VP44 label by itself therefore does not establish the controller arrangement: identify the installation. Pilot injection is shown as an optional function in Bosch’s EDC15M overview. Bosch, printed pages 16 and 66–67.
Start of delivery and start of injection
Start of delivery is not automatically the same event as start of injection at the nozzle. In Bosch’s distributor-pump and unit-injector examples, pressure builds after delivery begins and the nozzle then opens; pressure-wave travel also matters for a distributor pump. The relationship depends on the hardware and operating conditions. Interpret each diagnostic value according to its own definition. Bosch, printed pages 54–56.
- Needle-motion feedback: where a suitable sensor is fitted, the ECU can use a reference injector’s needle movement to compare actual injection timing with its target. Bosch notes that this feedback is not suitable for closing the loop during starting or overrun in its example.
- VP30/VP44 timing-device feedback: Bosch describes comparing an angle/time signal from inside the pump with the crankshaft signal to control timing-device position. This can operate during overrun; a needle-motion sensor can be an additional option on some systems.
- Unit-injector BIP feedback: Bosch describes detecting valve closure from the solenoid current waveform. This begin-of-injection-period (BIP) signal identifies the start of delivery, allowing a correction to a later actuation; it is not a direct measurement of nozzle opening. If the feedback is unavailable, Bosch describes a fallback to open-loop control.
- Common rail: Bosch’s example commands electrically operated injectors and separately controls rail pressure. Do not assume that it uses the distributor pump’s needle-sensor loop or the unit injector’s BIP strategy.
These are described control methods, not a guarantee that every implementation exposes the corresponding feedback or diagnostic value. Bosch, printed pages 54–56.
Example: 2001 Saab 9-3 D223L with VP44
The Saab workshop description identifies this particular car as EDC 15 with a VP44 pump. Its engine ECU calculates the permitted fuel mass per combustion and sends quantity and timing requests to the pump over the powertrain bus. The pump controls metering and the start of pressure build-up; its internal diagnostic results are sent to the engine ECU. The pump also contains the feed pump drawing fuel through the filter. Saab WIS, 2001 9-3 D223L.
On this Saab, the engine ECU and pump use a separate P-bus rather than the I-bus; the main instrument unit passes information between the buses. Saab describes the P-bus as ten times faster than the I-bus, without giving a numerical bit rate on this page. This is a description of this vehicle, not a universal EDC15 network layout.
Saab lists a cable-operated pedal potentiometer, crankshaft sensor, mass-air-flow and manifold-pressure sensors, and coolant, oil and intake-air temperature sensors. The coolant signal contributes to cold-start fuelling and overheating protection; the oil-temperature signal is also used to check coolant-temperature plausibility and for protection. The air-mass signal is used to calculate air per combustion, while manifold pressure is used for boost control. Intake-air temperature also affects some diagnostic enable conditions.
The same source lists vacuum-operated control valves for charge air, EGR and the swirl throttle, as well as a glow-control module, engine-management main relay and A/C relay. The glow module reports its own diagnostics to the engine ECU. Brake and clutch switches participate in cruise-control operation. The component numbers in Saab WIS identify components in that vehicle’s documentation; they are not ECU pin numbers.
Checking an unknown application
- Identify the injection hardware and whether the pump has its own controller. Consult the vehicle’s wiring and service information for the exact installation.
- Find out which feedback is actually fitted and what each scan-tool label represents before comparing requested and actual values.
- Confirm the ECU and software identifiers and the units, axes and function of any calibration definition. Do not transfer addresses, feedback assumptions or timing values between systems.
For operating requests and limits, see EDC15 fuel control and tuning basics. For scan-tool examples, see EDC15 diagnostic data and troubleshooting.
Sources
- Robert Bosch GmbH, Electronic Diesel Control (EDC), 2001, printed pages 15–18, 48–56 and 64–67; independent PDF mirror; accessed 10 November 2026. System figures are examples, and the general control chapters cover more than EDC15.
- Saab Workshop Information System, 2001 9-3 D223L, EDC 15 brief description; independent reproduction; accessed 10 November 2026. Applies to the documented vehicle and engine.