Electrical/Electronic System Specifications
Note. The values given below are measured between the terminals listed for the component unless otherwise stated. The values are approximate and must be used as guidelines. Component wear and aging may affect the values
Scheme 49
Scheme 50
The system relay for air conditioning (A/C) position 2 must activate when the ignition is switched on. Relay coil resistance terminals #1 and #2: 78 ohms.
Scheme 51
If the ignition is on, the blower fan relay must activate when the maximum fan speed is selected.
Relay coil resistance terminals #1 and #3: 128 ohms.
Scheme 52
Scheme 53
Climate control module terminal #A26 controls the speed of the blower fan via power unit terminal #3 using a pulse width modulation (PWM) signal which changes according to the setting for the fan selector.
Power unit terminals #4 and #2 then control the negative side of the blower fan motor depending on the pulsed signal from the climate control module.
Scheme 54
Scheme 55
See the power unit for information about controlling the blower fan.
Note. The blower fan should be test run to determine its condition. Listen for abnormal noise. Also check that the bearing and rotor blade in the fan are OK.
Climate Control Signal Specifications
All values listed below are measured between the respective terminal in column 2 (control module terminal) and terminal A8 (ground) unless otherwise stated in column 5 (other).
Climate control module connectors terminals #A1-30 and #B1-16 correspond to breakout box terminals #1-30 and #31-46.
Note. It is important that the breakout box is connected and that the ground terminals have been checked before readings are taken.
| U= | DC voltage in volts (V) | U bat = | Battery voltage (V) |
|---|---|---|---|
| I = | Current in amperes (A) | U low = | Voltage close to 0 V |
| F = | Frequency in Hertz (Hz) | % duty = | Duty cycle (pulse ratio) as a percentage (%) |
| Breakout box terminal | Control module terminal | Signal type | Ignition on | Other |
|---|---|---|---|---|
| 1 | A1 | 30-supply, power supply for the climate control module | U = U bat | With the ignition off U = U bat |
| 2 | A2 | Not connected | ||
| 3 | A3 | Not connected | ||
| 4 | A4 | Not connected | ||
| 5 | A5 | 15-supply, power supply for the climate control module | U = U bat | With the ignition off Uapprox.2 V |
| 6 | A6 | Input signal from the engine block heater timer. | U = U low /U bat | Parking heater On = U bat Off = U low |
| 7 | A7 | Input signal from the rheostat for panel lighting | F = 130 Hz (PWM) Increased duty cycle (+trigg) Gives brighter lighting level | Signal is a pulsed signal with fixed frequency and variable duty cycle. The pulse width varies according to the set lighting level. |
| 8 | A8 | Power ground | U = U low | Ground terminal, measured to the battery negative terminal |
| 9 | A9 | Communication cable for the left seat heater module | Pulsed signal between U low and U bat if the seat heater is ON (the high or low heat level is activated). | The climate control module transmits a number of pulses depending on whether the selected seat heat level is high or low. High = multiple pulses (depending on the programmed seat temperature) Low = fewer pulses (depending on the programmed seat temperature) Seat heater off U = 0-2 V below U bat . |
| 10 | A10 | Communication cable for the right seat heater module | Pulsed signal between U low and U bat if the seat heater is ON (the high or low heat level is activated) | The climate control module transmits a number of pulses depending on whether the selected seat heat level is high or low. High = multiple pulses (depending on the programmed seat temperature) Low = fewer pulses (depending on the programmed seat temperature) Seat heater off U = 0-2 V below U bat . |
| 11 | A11 | Output signal from the DSA control module from the DSA switch on the climate control module panel | U= less than 5 V/greater than 5.6 V | DSA system On = greater than 5.6 V Off = less than 5 V |
| 12 | A12 | Control signal + for damper motor air distribution | The plus winding for the motor is activated: U = 2-4 V below Ubat. The negative winding for the motor is not activated: U = less than 1 V | The damper motor is activated by turning the air distribution selector |
| 13 | A13 | Control signal - for damper motor air distribution | The negative winding for the motor is activated: U = 2-4 V below U bat . The plus winding for the motor is not activated: U = less than 1 V | The damper motor is activated by turning the air distribution selector |
| 14 | A14 | Control signal + for temperature damper motor | The plus winding for the motor is activated: U = 2-4 V below U bat . The negative winding for the motor is not activated: U = less than 1 V | The damper motor is activated by turning the temperature selector. |
| 15 | A15 | Control signal - for temperature damper motor | The negative winding for the motor is activated: U = 2-4 V below U bat . The plus winding for the motor is not activated: U = less than 1 V | The damper motor is activated by turning the temperature selector |
| 16 | A16 | Control signal + for recirculation damper motor | The plus winding for the motor is activated: U = 2-4 V below U bat . The negative winding for the motor is not activated: U = less than 1 V | The damper motor is activated when recirculation is engaged |
| 17 | A17 | Control signal - for recirculation damper motor | The negative winding for the motor is activated: U = 2-4 V below U bat . The plus winding for the motor is not activated: U = less than 1 V | The damper motor is activated when recirculation is engaged |
| 18 | A18 | Power supply to the position sensor for the temperature damper motor | U= 4.6-5.2 V | |
| 19 | A19 | Input signal from the position sensor for the temperature damper motor | U=U low - 5 V | The voltage changes when the damper motor changes position |
| 20 | A20 | Signal ground for the position sensor for the temperature damper motor | U = U low | |
| 21 | A21 | Power supply to the position sensor for the air distribution damper motor | U= 4.6-5.2 V | |
| 22 | A22 | Input signal from the position sensor for the air distribution damper motor | U=U low - 5 V | The voltage changes when the damper motor changes position |
| 23 | A23 | Signal ground for the position sensor for the air distribution damper motor | U = Ulow | |
| 24 | A24 | Control signal to the blower fan relay for blower fan maximum speed. | U = U low /U bat | The blower fan relay is only activated when maximum speed is selected on the blower fan control. On = U low Off = U bat |
| 25 | A25 | Control signal for the defroster relay (rear windshield and door mirror heating) | U = U low /U bat | The defroster relay is activated when the defroster switch on the climate control module panel is pressed On = U low (LED lit) Off = U bat (LED not lit) |
| 26 | A26 | Control signal to the power stage | U = U low - approximately 2 V | Signal is a pulsed signal with fixed frequency and variable duty cycle. The pulse width varies according to the set blower speed fan. |
| 27 | A27 | Diagnostic signal from the blower fan motor | U = U low - U bat | Re-supply of the signal voltage from the blower fan motor. The voltage reduces as the fan speed increases. |
| 28 | A28 | Not connected | ||
| 29 | A29 | Not connected | ||
| 30 | A30 | Diagnostic lead | U = 0-4 V below U bat | If no communication can be established. Other values apply if the fault-tracing instrument is connected to the socket. |
Scheme 56
| U= | DC voltage in volts (V) | U bat = | Battery voltage (V) |
|---|---|---|---|
| I = | Current in amperes (A) | U low = | Voltage close to 0 V |
| F = | Frequency in Hertz (Hz) | % duty = | Duty cycle (pulse ratio) as a percentage (%) |
| Breakout box terminal | Control module terminal | Signal type | Ignition on | Other |
|---|---|---|---|---|
| 31 | B1 | Input signal from the outside temperature sensor | U=U low -4.85 V | Applies only to electronic climate control. The voltage varies with the outside temperature. The resistance is approximately 4.8 kohms at approximately 20°C. See Electrical/electronic system specifications for additional values |
| 32 | B2 | Signal ground for the outside temperature sensor | U=U low | Applies only to ECC |
| 33 | B3 | Input signal from the evaporator temperature sensor | U=U low -4.85 V | Applies only to ECC, MCC. The voltage varies with the evaporator temperature. The resistance is approximately 4.8 kohms at approximately 20°C. See Electrical/electronic system specifications for additional values. |
| 34 | B4 | Signal ground for the evaporator temperature sensor. | U=U low | Applies only to ECC, MCC |
| 35 | B5 | Input signal from the engine coolant temperature (ECT) sensor. | U=U low -4.85 V | Applies only to electronic climate control. The voltage varies with the engine coolant temperature (ECT). The resistance is approximately 4.89 kohms at approximately 20°C. See Electrical/electronic system specifications for additional values. |
| 36 | B6 | Signal ground for the engine coolant temperature (ECT) sensor | U=U low | Applies only to ECC |
| 37 | B7 | Input signal from the sun sensor | U=U low -4.85 V | Applies only to electronic climate control. Voltage varies with the sun intensity. |
| 38 | B8 | Signal ground for the sun sensor | U=U low | Applies only to ECC |
| 39 | B9 | Not connected | ||
| 40 | B10 | Speed signal from the combined instrument panel | F= Increases with vehicle speed Pulsed signal between U low and U bat . | Applies only to electronic climate control. Signal is a pulsed signal with fixed duty cycle and variable frequency. The frequency changes with vehicle speed. |
| 41 | B11 | Input signal from the from windshield wiper. | U = U low /U bat | Applies only to ECC Check if the windshield wipers are in use On = U bat Off = U low |
| 42 | B12 | Input signal from the generator (GEN) D+ | Input signal from the generator (GEN) D+ U = 1.5 V / U bat | Applies only to electronic climate control. Check if the engine is running. Engine not running but ignition on, U = 1.5 V Engine running, U = U bat |
| 43 | B13 | Output signal to the engine control module (ECM), A/C request | U = U low /U bat | Applies only to electronic climate control, manual climate control. When the A/C switch on the climate control module panel is pressed On = U bat (A/C LED lit) Off = U low (A/C off LED lit) |
| 44 | B14 | Not connected | ||
| 45 | B15 | Not connected | ||
| 46 | B16 | Not connected |
Signal specification Additional heater 912-D/B
General
All values given below are between the respective terminal in column 1 and terminal #3 (power ground) unless otherwise stated in brackets after the table entry. Control module terminals #1-#16 correspond to #1-#16 on the breakout box.
Note. It is important to connect the breakout box and check ground terminals before taking readings.
| U= | DC voltage in volts (V) | U AC = | AC voltage in volts (V) |
|---|---|---|---|
| U bat = | Battery voltage (V) | F= | Frequency in Hertz (Hz) |
| U low = | Voltage approximately 0 V | % duty= | Duty cycle (pulse ratio) as a percentage (%) |
| T= | Time in milliseconds (ms) |
| Terminal | Signal type | Ignition on | Engine idling | Remarks |
|---|---|---|---|---|
| #1 | Glow plug signal | Glow plug off: U=U low Glow plug on: Pulse ratio (% duty) 0% | Pulse ratio (% duty) increases with glow plug intensity. | |
| #2 | Control signal passenger compartment blower fan (when installed as accessory) | No accessory installation: Uapprox. 0 V Relay installed Relay not activated: Uapprox. 12 V Relay activated: U less than 2.5 V | ||
| #3 | Power ground Measured to battery negative terminal (-) | U low | ||
| #4 | Signal ground, outside temperature sensor, Coolant temperature sensor and flame sensor | U low | ||
| #5 | Signal from generator (GEN) | U < 2.75 V | U > 7 V | |
| #6 | Diagnostic lead, K-link | U approx. 8.1 V | U approx. 9.8 V | If the fault tracing-instrument is connected the other values apply |
| #7 | Outside temperature sensor signal | +20°C: U approx. 0.5 V | Voltage increases with decreasing temperature | |
| #8 | Flame sensor signal | Flame not lit: U approx. 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 | Combustion fan, fuel pump and water pump power supply | 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 | Frequency increases with pump speed | |
| #14 | Timer control signal | Timer active: U > 7 V Heater start after rest: U < 2.75 V Remarks: 2.75 V < U < 7 V | ||
| #15 | 15-supply (power supply from ignition switch) | U bat | U bat | |
| #16 | Coolant temperature sensor signal | +20°C: U approx. 3.5 V | Voltage decreases with increasing temperature | |