Signal Specification
All values given below are between the respective terminal in column 1 and terminal #3 (power ground) unless otherwise stated in brackets after the entry. Control module terminals #1-#16 correspond to terminals #1-#16 on the breakout box.
NOTE:
It is important to connect the breakout box and check the ground terminals before taking readings.
| U= | DC voltage in volts (V) | UAC = | AC voltage in volts (V) |
| Ubat = | Battery voltage (V) | f = | Frequency in Hertz (Hz) |
| Ulow = | Voltage approximately 0 V | % duty = | Duty cycle (pulse ratio) as a percentage (%) |
| t = | Time in milliseconds (ms) | - | - |
| Terminal | Signal type | Ignition on | Engine idling | Other |
| #1 | Glow plug signal | Glow plug off: U=Ulow Glow plug on: Pulse ratio (% duty) > 0% |
Pulse ratio (% duty) increases with glow plug intensity. | |
| #2 | - | - | - | |
| #3 | Power ground (Measured to the battery negative terminal) |
U low | - | |
| #4 | Signal ground, engine coolant temperature sensor and flame sensor | U low | - | |
| #5 | - | - | - | |
| #6 | Communication cable for the central electrical module (CEM) | - | Digital signal | - |
| #7 | - | - | - | - |
| #8 | Flame sensor signal | Flame not lit: U≈5 V Flame lit: U<1.5 V |
- | |
| #9 | 30-supply (Power supply from battery) | U bat | - | |
| #10 | Combustion fan control signal | Combustion fan off and power supply off: U low Combustion fan off and power supply on: U bat Fan on: Pulse ratio (% duty) > 0% |
The pulse ratio (% duty) increases with fan speed. | |
| #11 Model year -2001 |
Power supply, combustion fan, fuel pump (FP) and water pump | Power supply off: U low Power supply on: U bat |
- | |
| #11 Model year 2002- |
Power supply, combustion fan and water pump | Power supply off: U low Power supply on: U bat |
- | |
| #12 | Water pump control signal | Water pump off and power supply off: U low Water pump off and power supply on: U bat Water pump on and power supply on: U low |
- | |
| #13 | Fuel pump control signal | Fuel pump off: f=0 Hz Fuel pump on: f>0 Hz |
The frequency increases with pump speed | |
| #14 | - | - | - | |
| #15 | Extended X-supply | U bat | U bat | - |
| #16 | Coolant temperature sensor signal | +20°C: U ≈ 3.5 V +75°C= 2.02 V +90°C= 0.78 V |
The voltage decreases with increasing temperature | |