Windshield Washer Control Module: Description and Operation

Central Timer Module (CTM)












This module has two versions:
^ a standard version for vehicles with manual transmission
^ an extended version for vehicles with automatic transmission

Functions of the CTM standard version:
^ Intermittent wiper, front
^ Intermittent wiper, rear
^ Rear window washer with wiper function
^ Front windscreen washer with wiper function
^ Heated rear window
^ Heated windscreen
^ Entry Illumination
^ Power saving relay
^ Required acoustic signal from trip computer module, anti-theft warning system/double locking module and airbag module
^ Lights-on Warning Chime Unit

Additional functions of the CTM extended version:
^ Safety belt warning
^ Reverse gear warning
^ Ignition key warning
^ Warning - shift lever not in park position

Intermittent wiper, front
If the wiper control switch is switched to Intermittent position while the ignition is on, then the wipers will operate at fixed intervals (8.0 ± 2.0 seconds). In the case of vehicles with variable delay units, the time between wipe operations can be set from "1" to "6" (1.0 - 22.0 seconds) using the potentiometer on the multi-function switch. The intermittent wipe operation mode periodically repeats until the Intermittent switch setting is turned off. If the potentiometer is used to change the delay time during intermittent mode, then the wiper cycle is completed before the new delay time takes effect. If the switch is turned off and on again during the wiper interval, then intermittent mode immediately begins again at the delay time set. The CTM sends respective ground pulses to the front windscreen wiper relay, whereupon the relay activates the front windscreen wiper motor.

Intermittent wiper, rear
If the rear wiper control switch is switched on while the ignition is on, then the rear wipers will operate at fixed intervals (12.0 ± 3.0 seconds). After every completed wiper operation and delay time, the CTM sends a pulse (0.6 ± 0.2 seconds) to the rear wiper relay. The rear wiper motor is switched off by its own limit switch.

Rear window washer with wiper function
If the rear window washer switch is operated, the washer pump and the rear window wiper are switched on. If the rear window washer switch is released, the washer pump is immediately switched off. The run-on time for the rear wiper is (4.0 s ± 1.0 s). The duration of the ground pulse for the rear wiper relay is transmitted by the CTM and amounts to 0.6 s ± 0.2 s.

Front windscreen washer with wiper function
If the front windscreen washer switch is operated, the washer pump and the front windscreen wiper are switched on. If the front windscreen washer switch is released, the washer pump is immediately switched off. The front windscreen wiper motor performs another 2-3 wiper cycles and is then switched off by the CTM by means of the front wiper relay or the limit switch.

Heated Rear Window
To switch on the heated rear window, the heated rear window switch must be pressed for at least 30 ms. The heated rear window will then be switched on for 10 min ± 2 min via the heated rear window relay. During these 10 mins the heated rear window can be switched off either by pressing the heated rear window switch again, or by turning off the ignition. Under these conditions, the CTM sends a ground signal to the heated rear window relay, which in turn switches the heated rear window. If the ignition switch in turned to "Start" while the heated rear window is switched on, then the heater will be temporarily switched off during this time.

Heated windscreen
To switch on the heated windscreen, the heated windscreen switch must be pressed for at least 30 ms. The heated windscreen will then be switched on for 4 min ± 1 min via the heated windscreen relay. During these 4 mins the heated windscreen can be switched off either by pressing the heated windscreen switch again, or by turning off the ignition. The heated windscreen can only be activated when the generator is supplying voltage, i.e. when the engine is on. Under these conditions, the CTM sends a ground signal to the heated windscreen relay, which in turn switches the heated windscreen.

Entry Illumination
For vehicles without remote control: The interior light will be switched on when one of the doors is opened, regardless of the ignition key position, as long as the vehicle is unlocked and the interior light switch is in the "Delay" position. Within 0.5 s, the CTM regulates the lights from off to full brightness. When the doors are closed, there are two options. The interior light remains at full brightness for 20 s and then dims to darkness within 5 s. If the ignition is switched on after closing the doors, then the light will be dimmed out within 2 s.

For vehicles with remote control: If the vehicle is unlocked using remote control, then the ATWS/double locking system operates the CTM. This regulates the lights from darkness to full brightness within 0.5 s, before a door is opened. If the vehicle is locked using the remote control, then the interior light is dimmed out within 2 s.

If the ignition is switched off before the exterior lighting, then the interior lights come on for 20 s at full brightness before dimming out within 5 s. The same thing happens when the exterior lighting is switched off while the ignition is on, and the ignition then is switched off within 20 s.

30 mins after switching off the ignition, the interior lighting is switched off by the CTM by means of the power saving relay if one of the doors is open and the interior lighting switch is in "Delay" position.

The luggage compartment light is not controlled by the CTM.

Power saving relay
30 mins after switching off the ignition, the CTM turns off the power saving relay and switches to Off mode. This mode applies until one of the following occurs:
Unlocking by remote control, opening a door or the tailgate, or switching the ignition key to "Radio" or "Ignition" position. The power saving relay is then reactivated by the CTM and supplies current back to the components that it switched off in the vehicle (interior lighting, electric mirror adjustment mechanism).

Acoustic Signal
The following modules request acoustic signals from the CTM: Trip computer module, anti-theft warning system double locking module and airbag module. Since the requesting modules do not have an acoustic warning system, they send a ground pulse to the corresponding input on the CTM, at which point the CTM in turn sends a defined acoustic signal. The CTM determines which acoustic signal has to be transmitted from the length of the input pulse. The airbag module sends a ground signal to the CTM if the warning lamp in the instrument cluster bezel is activated by the CTM, but is faulty. Otherwise, the airbag module sends a ground signal to the CTM each time the ignition is switched on, in order to maintain the contact to the module connector. The trip computer module sends a ground signal to the CTM if the fuel level drops below a certain level, or to confirm each time one of the trip computer module switches is pressed.

Lights-on Warning Chime Unit
If the driver's door is opened when the ignition is switched off and the parking light, dipped beam or main beam are still on, then the warning buzzer sounds (integrated in the CTM). The buzzer stops when the exterior lighting is switched off, the driver's door is closed or the power saving relay switches off after 30 mins.

Safety Belt Warning
If the ignition is switched on and the safety belt is not fastened, then the warning buzzer sounds for 4 to 8 s and the belt buckle warning lamp in the instrument cluster comes on. The warning lamp goes out if the safety belt is fastened into the buckle within 80 s ± 15 s. If this happens while the buzzer is still operating, then this stops as well. The warning lamp stays on if the seat belt buckle is not operated within 80 s. The input signal is transmitted to the CTM when contact is made at the seat belt buckle.

Reverse gear warning
In vehicles with automatic transmission, an audible warning with a frequency of 3 Hz is output after 0.8 s if the shift lever is switched to "R" (reverse gear). The input signal is transmitted from the transmission range (TR) sensor to the CTM.

Ignition key warning
An acoustic signal is transmitted from the warning buzzer in the CTM when the ignition key is turned to "R" or "Off" position and at the same time the driver's door is opened. The input signals are transmitted from the ignition key position sensor and from the driver's side door switch to the CTM.

Warning - shift lever not in park position
An acoustic signal is transmitted from the warning buzzer in the CTM if the shift lever is not placed in position "P" (park position) and at the same time the driver's door is opened. The input signals are transmitted from the TR sensor and from the driver's side door switch to the CTM. The buzzer stops when the shift lever is placed in position "P", the driver's door is closed or the power saving relay is switched off after 30 mins.

The acoustic signal is also transmitted if the lighting warning signal and the park position signal are transmitted at the same time. The buzzer stops only when the conditions for its activation no longer apply, i.e. when the shift lever is in position "P", the driver's door is closed or the exterior lighting is switched off.


Trip Computer Module







The trip computer module has the following functions:
^ Low level of washer fluid warning
^ Ice warning
^ Outside temperature display in °C or °F
^ Average fuel consumption display in liters per 100 kms or mpg
^ Display of current fuel consumption in liters per 100 km or MPG (miles per gallon)
^ Display of distance remaining in km or m
^ Display of average speed in km/h or mph

An acoustic confirmation signal sounds every time a switch is operated (set and reset button on the module, or operating switch on the steering column switch). This signal is transmitted by the CTM on the request of the trip computer.

Low level of washer fluid warning
The contact is the washer fluid reservoir transmits a ground signal to the trip computer module when the fluid drops below a certain level. A routine is then performed to stop the display from fluctuating rapidly as a result of reservoir movement. The warning lamp comes on after approx. 30 seconds.







Ice warning
The ambient temperature gauge supplies the trip computer module with the current ambient temperature. At certain temperature changes, the trip computer module outputs an ice warning to warn the driver of black ice on the road:

Ambient temperature display
The trip computer module converts the resistance values supplied by the ambient temperature sensor. Temperatures between -40 °C and + 65 °C / -40 °F and +149 °F can be displayed. If the readings are outside this range or the circuit is broken or shorted, then this is displayed as "--°C" or "-- °F". The module corrects temperature readings that are affected by the heat of the engine. When the ignition is turned off, the last value displayed is stored for one hour.

Average fuel consumption display in liters per 100 km or mpg

The average fuel consumption is calculated for the last 1000 km traveled, or for the time since the last reset. The display is not updated until the change amounts to more than 1 litre per 100 km/min or 2 mpg/mm.

Current fuel consumption display in liters per 100 kms or mpg

The instantaneous fuel consumption in litre/100 km is calculated according to the following formula:

100 x fuel consumption in the last second / distance covered in the last second

The instantaneous fuel consumption in miles per gallon is calculated according to the following formula:

distance covered in the last second / fuel consumption in the last second

A maximum value of 55 litres/100 km or 99 mpg can be displayed. If the signal from the vehicle speed sensor (VSS) falls below 7 Hz, i.e. 5 km/h, then the display changes to liters per hour. If the signal increases to 9 Hz, then the display reverts to liters per 100 km.







Display of distance remaining
The distance remaining is calculated according to the following formula:

100 x current fuel level / average consumption The trip computer module calculates the current fuel level from the resistance values that the fuel gauge sender unit outputs:

Since the input value fluctuates constantly because of the movement of the fuel in the tank, the trip computer module processes the value after a time delay using an algorithm. If the circuit to the fuel gauge sender unit is broken or shorted, the following display is output: (---)

An acoustic warning signal is transmitted by the CTM when the following remaining distances are calculated:
80 km (50 miles), 40 km (25 miles), 20 km (10 miles) and 0 km (0 miles). In this case the display automatically switches over to remaining distance, regardless of which mode it is in.

The remaining distance displayed is not updated if the distance traveled is less than 5 km (3 miles) or if the ignition has been switched on for less than five minutes. If the tank is filled with more than 9 liters (2 gallons), the value is immediately re-calculated and displayed.

Display of average speed
The average fuel speed is calculated for the last 1000 km traveled, or for the time since the last reset. If the current speed increases at a rate faster than 1 km/h/s, the display will not be updated.







Anti-theft system/double locking module
There are five versions of this module with the following features:
^ Central locking
^ Central locking and remote control
^ Central locking, double locking and remote control
^ Central locking, double locking, remote control and alarm system
^ Central locking, double locking, remote control and alarm system with infrared interior scanning.

For further information, see Power Locks, Keyless Entry, Anti-theft Alarm Systems.