Description

What is the purpose of this function?

The diagnostics function allows you to individually control all operator and display elements, such as solenoid valves, relay outputs or warning lights (actuators) in a cyclic manner. Simultaneously to the control action, the software evaluates the status of the controlled output and returns it to the diagnostic systems as the response. If an output is defective, this function therefore allows you to immediately determine whether the output is electrically OK, or the electric circuit is faulty due to short-circuit or cable break. To obtain an audible or visual feedback from the actuators, the outputs are cycled with a low frequency. It is therefore possible to test whether a solenoid valve works smoothly without dismounting or opening the transmission. The test divides into the following subfunctions:

• Solenoid valve test - [ MV ] button
• Sense line test - [ SENSE ] button
• Test of digital outputs - [ REL ] button

Automatic test - [ F2 ] key

An automatic actuator test is started after pressing F2. All actuators are briefly operated (solenoid valves) and/or controlled (measuring coil test) to detect their status. Depending on the diagnostic level, a distinction is made between:

Displayed as text	Displayed as symbol
Defect
Line interruption
Short-circuit
Not defined in dataset	[ - ]
Control action ok

If the control action is defective, the fault memory enables a detailed description of the actuator and its circuit diagram. It also provides a repair instruction.

Individual test

Each actuator can be controlled separately. For this purpose, click on its button or enter the appropriate identifying letter. The individual test will run until you connect another actuator, exit the menu, or if a condition required for actuator control is no longer met. The individual test is primarily intended to find loose contacts. While the test is running, you may, for example, shake the cable or the plug connection to find a defective contact. If faults occur during the measuring coil test, the relevant test must be restarted.

SV supply (dS)

This field indicates whether or not solenoid valve supply voltage is present. All actuators are supplied via the dS relay. A defective relay is pointed out by a "red circle" in the window. A "green check mark" means that the SV supply is applied correctly.

Solenoid valve measuring coils

The solenoid valve measuring coils are shown in the right-hand column (EKM, DKM, SKM, PBM, RBKM and TBM).
Four different displays indicate whether or not the measuring coil circuits work properly.

• In the text window
• By a mark in the appropriate actuator window
• By the voltage curve shown in the view window
• By the mean voltage value at the integrator

The measuring coil circuits lead to two integrators IGR1 and IGR2 which determine the force generated by the solenoid plunger based on the voltage value measured there. Integrator 1 is connected to the measuring windings of solenoid valves EK, DK, SK and PB - integrator 2 determines the voltage values at the measuring coils of RBK and TB.
. The mean voltage value found during the solenoid coil test should be approx. 1.8 V.

ATTENTION! - Measuring coil faults are not written to the fault memory.

Solenoid valve power coils

The solenoid valve power coils are shown in the left-hand column of the actuator test window (EK, DK, SK, PB, RBK, TB, WP, WR, RBG and TB). The power coils are controlled cyclically. An audible feedback signal allows conclusions as to whether the solenoid valve is mechanically ok or jammed.

The following solenoid valves are installed in the transmission:

• EK - Control solenoid valve input clutch
• TB - Control solenoid valve turbine brake
• PB - Control solenoid valve pump brake
• DK - Cntrol solenoid valve lock-up clutch
• SK - Control solenoid valve overdrive clutch - 4-gear transmissions only
• RBK - Control solenoid valve converter brake / reverse gear - small piston area
• RBG - ON/OFF solenoid valve converter brake / reverse gear - large piston area
• WP - ON/OFF solenoid valve converter outlet valve - uncontrolled pressure
• WP - ON/OFF solenoid valve converter outlet valve - controlled pressure

SENSE line test

If the Sense line is connected to transmission ground, this may result in hard shiftings. The test is based on the fact that in a measuring coil, where the power coil is not under power, no voltage is inducted. The SENSE line test is displayed by a dial instrument whose indicator is steady in the centre position at approx. 1.2 V if the SENSE line is in order. In the event of a fault, the voltage will creep to one of the invalid ranges below 0.8V and/or 1.6V. The test may be retriggered any time by pressing the [ F3 ] key.

Relays and variable outputs

The relay outputs are controlled cyclically. An audible feedback allows conclusions as to the mechanical condition of the controlled relay.

ATTENTION! - Relays need not be connected to the relay outputs.
For example, signal lamps may be connected directly (TL, ZW, TOEL). In this case, there will be no audible feedback but the controlled element will flash.

The following functions may be activated in the control unit:

• ZW - Central warning light
• dW - Converter brake relay
• dN - Speed switch relay
• dR - Reversing light relay
• TL - Gear range selector lighting
• dHSB - Relay for bus stop brake
• dNEUTR - Indicator for power connection between engine and transmission
• +FB/+HB - Supply voltage of brake pedal/lever (see special notes)
• TOEL - Transmission oil temperature warning lamp
• MMR - Signal for engine torque reduction

Fault priority of digital outputs

The fault priority of digital outputs can be changed during the test.
The priority levels (B), (C) and (OFF) are available.
(B) - The fault is entered in the fault memory and indicated by the lamps of the gear range selector.
(C) - The fault is entered in the fault memory. If a fault occurs, it will not be indicated by the gear range selector.
(OFF) - The fault is not entered in the fault memory. If a fault occurs, it will not be indicated by the gear range selector.
All settings are activated during the next operating cycle, i.e. after ignition OFF/ON.

What to do if a fault is displayed?

If the control action is defective, the fault memory (diagnostic function B in main menu) allows you to view a detailed description of the actuator and its circuit diagram. It also provides a repair instruction.

Special notes

• When testing output +FB/+HB, a fault is indicated if foot brake pedal or hand brake lever/switch is not operated.
• If you control solenoid valve SK in a 3-gear transmission, you are informed that this solenoid valve is not activated in the dataset. This solenoid valve is not installed in the 3-gear unit.
• If the speed signal lines are not properly screened due to an installation fault between the control unit and transmission, frequency coupling may occur while the solenoid valves are being cycled and the actuator test may therefore be cancelled because one of the safety conditions (no engine speed) is violated.