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CITROËN TECHNICAL TRAINING PRESENTATION OF THE AL4 AUTOMATIC TRANSMISSION CITROËN UK LTD 221 BATH ROAD SLOUGH SL1 4BA DEALER PERSONNEL DEVELOPMENT AND TRAINING CITROËN UK LTD. Reproduction whether partial or in full without written permission from Citroën UK Ltd is forbidden A DOCUMENT SUMMARY PRESENTATION OF THE The aim of this document is to give a brief description of the design and operation of the electronically managed AL4 automatic transmission which offers precise, adaptive control as well as excellent gear changing quality. The following subjects are dealt with in this document: - Presentation of the transmission and various pieces of information, - The selector control, - Lubrication, - The converter, - The mechanism, - The ECU, - Auto-diagnostics, - The electrical circuit, - Unit maintenance. B CONTENTS CHAPTER 1 : PRESENTATION - GENERAL... PAGE 1 I - INTRODUCTION... PAGE 1 II - PRESENTATION... PAGE 2 III - DESCRIPTION OF THE... PAGE 3 IV - IDENTIFYING THE COMPONENTS OF THE AUTOMATIC TRANSMISSION... PAGE 5 V - SPECIFICATIONS - SERVICING... PAGE 7 VI - LAYOUT OF THE... PAGE 8 VII - MISCELLANEOUS ADVICE... PAGE 9 CHAPTER 2 : SELECTOR CONTROL... PAGE 11 I - SELECTOR LEVER... PAGE 11 II - PROGRAM SELECTOR... PAGE 13 CHAPTER 3 : CHECKING THE OIL LEVEL... PAGE 15 CHAPTER 4 : THE TORQUE CONVERTER... PAGE 17 I - DESCRIPTION... PAGE 17 II - CONVERTER LOCK-UP... PAGE 18 CHAPTER 5 : THE EPICYCLIC GEAR TRAIN... PAGE 21 I - DESCRIPTION... PAGE 21 II - OPERATING PRINCIPLE... PAGE 23 CHAPTER 6 : ECU... PAGE 27 I - ECU FUNCTIONS... PAGE 27 II - OPERATING SUMMARY... PAGE 31 III - ECU CONNECTIONS... PAGE 33 CHAPTER 7 : AUTO-DIAGNOSTIC... PAGE 35 I - FAULT WARNINGS... PAGE 35 II - MEMORISED FAULTS / DOWNGRADED MODES... PAGE 36 C CONTENTS CHAPTER 8 : WIRING DIAGRAM - XANTIA... PAGE 37 PETROL ENGINE/WITHOUT CRUISE CONTROL I - LAYOUT... PAGE 37 PETROL ENGINE/WITH CRUISE CONTROL I - LAYOUT... PAGE 38 DIESEL ENGINE/WITHOUT CRUISE CONTROL I - LAYOUT... PAGE 39 DIESEL ENGINE/WITH CRUISE CONTROL I - LAYOUT... PAGE 40 II - PARTS LIST... PAGE 41 CHAPTER 9 : AFTER-SALES OPERATIONS... PAGE 43 I - DOWNLOADING... PAGE 43 II - CONFIGURATION... PAGE 43 III - PEDAL PROGRAMMING... PAGE 44 IV - INITIALISING THE OLD OIL COUNTER... PAGE 44 V - UPDATING THE OLD OIL COUNTER... PAGE 44 VI - TEST AFTER REPAIR WORK... PAGE 44 VII - CHANGING PARTS, OPERATIONS TO BE PERFORMED... PAGE 45 VIII - AUTHORISED OPERATIONS DURING THE WARRANTY PERIOD PAGE...46 IX - AUTOMATIC TRANSMISSION REPAIR BY THE CITROËN AUTOMATIC TRANSMISSION CENTRE, SOUTH WEST PARIS... PAGE 47 X - SPECIAL TOOLING... PAGE 50 XI - DIAGNOSTIC TOOLING...51 D 1 Chapter 1 PRESENTATION - GENERAL I - INTRODUCTION AL4001D Electronically operated transverse automatic transmission. Four forward gears and one reverse gear. Fuzzy logic auto-adaptive ECU which controls the converter, gear changes and specific programs. The maximum torque capacity is 210 mn. Sealed transmission with reduced maintenance. Transmission oil cooled by heat exchanger. Current application: CITROËN XANTIA PHASE II vehicles with XU Petrol and Diesel engines. 2 Chapter 1 II - PRESENTATION Transmission layout Hydraulic torque converter with lock-up device. Primary shaft. Two Simpson 2 type epicyclic gear trains. Multiplate clutches. Multidisc and band brakes. Step down gear in central position. Differential with sealed outputs. Control This is performed by: the hydraulic unit, the ECU, a cable control. Features Lock-up of 2nd, 3rd and 4th gears. Electronic control of all regulation and gear changing functions. Three programs offered to driver: Auto adaptive - Sport - Snow Gears and programs displayed on dashboard. Cannot change up a gear in the no load position. User interface performed by a stepped selector grid with Shift-Lock safety function and program push buttons. 1st imposed position selected using push button. Auto adaptive Flash EEPROM ECU. Downgraded operation in the event of a fault. Closed loop operation. On board diagnostics. Selector lever not in position P reminder buzzer. Important: The automatic transmission ECU is linked to the engine management ECU so as to obtain: - good driving pleasure, - efficient mechanical protection for transmission and engine, - increased operating safety, - compliance with antipollution standards. 3 Chapter 1 III - DESCRIPTION OF THE A - CROSS SECTION AL4002P 4 Chapter 1 B - PARTS LIST 1 - Converter 2 - Input shaft 3 - Fitted oil pump 4 - Secondary pinion of step down gear 5 - Park wheel 6 - Secondary shaft 7 - Drive pinion 8 - Ring 9 - Differential unit 10 - Cover 11 - Adjustable plate 12 - Hydraulic distributor (DH) 13 - Manual valve 14 - Auxiliary hydraulic distributor (DHA) 15 - Clutch E1 (Reverse and 1st) 16 - Clutch E2 (2nd, 3rd, 4th) 17 - Hub 18- Brake F1 (4th) 19 - Brake F2 (Reverse) 20 - Brake F3 (1st and 2nd) 21 - Epicyclic gear train 22 - Primary pinion of step down gear 5 Chapter 1 IV - IDENTIFYING THE COMPONENTS OF THE AUTOMATIC TRANSMISSION A - AUTOMATIC TRANSMISSION The automatic transmission identification is engraved on the rear housing. 20TP15 A B AL4003D A - Component reference B - Serial number 6 Chapter 1 B - ECU SIEMENS S A 0/ / / M A D E N F R A N C E BVA AL4004D F C D E SIEMENS S A 0/ / / M A D E I N F R A N C E BVA G H I C - Siemens reference D - Siemens serial number E - Siemens number bar code F - Serial number G - Software version H - Hardware version I - Customer number bar code 7 Chapter 1 V - SPECIFICATIONS - SERVICING A - FREQUENCY - CAPACITIES B - GEARS XANTIA Engine XUD9 BTF/XU10J4R/XU7JP4 Transmission capacity Approximately 6 litres Draining capacity Approximately 3 litres Exclusive oil CITROËN Draining interval Lubricated for life Top-up interval km Transmission lubrication Pressurised Final drive lubrication Pressurised Weight 70 kg with oil and ECU Torque capacity 210 mn from 2000 to 4500 rpm XANTIA Engine XUD9BTF XU10J4R XU7JP4 Transmission type 20TP04 20TP05 20TP06 Tyres - circumference 205/60R m 185/65R m Gear ratios Rd Rdem Vveh Rd Rdem Vveh 1st nd rd th Reverse Step down gear 52x67 52x67 Cylindrical torque 25x71 23x73 Tachometric torque 24x20 24x20 Speeds in km/h are given for 1000 rpm. Rd = driveshaft ratio / Rdem = demultiplication ratio Vveh = Vehicle speed. Internal gear change safety thresholds: LEVER POSITION SAFETY THRESHOLD km/h 155 km/h 2 73 km/h 103 km/h 2 + press on 1 button of program selector 35 km/h 48 km/h R 15 km/h 19 km/h R + foot on brake 25 km/h 34 km/h 8 Chapter 1 VI - LAYOUT OF THE Mechanics (engine) Automatic transmission C o n v e r t e r Epicyclic gear train Electro-hydraulics Throttle potentio-meter P u m p Electro-hydraulic distributor Dist. Dist. Dist. Electr-onics Kick-down info Oil. Braking info. AT ECU Exchanger oil flow setting throttle α P/N - D - Gear change Engine management computer MIL illumin request Final drive + differential ShiftLock S 1st Selector ever Prog. elec-tor Display Buzzer Rev counter Control panel AL4005P C m = Engine torque C r = Torque at road wheels ω m = Engine speed ω e = Gear train input speed ω s = Gear train output speed ω r = Road wheel speed 9 Chapter 1 VII - MISCELLANEOUS ADVICE A - TOWING The transmission is lubricated when the engine is running since this drives the transmission oil pump. Thus, when towing, the drive wheels must be raised off the ground. However, the vehicle may be towed with the drive wheels on the ground under exceptional circumstances and provided that the following conditions are complied with: the selector lever must be in position N, do not add any oil, do not exceed 50 km/h over a distance of 50 km. B - DRIVING Never drive with the ignition switched off. Never push the vehicle to try and start it (not possible with automatic transmission). Note: The automatic transmission is only lubricated when the engine is running. C - OPERATIONS ON ELECTRICAL COMPONENTS Never disconnect: the battery whilst the engine is running, the ECU whilst the ignition is switched on. Before reconnecting a connector, check: the condition of the various contacts (bent, rusted...), that the mechanical locking device is present and check its condition. During electrical inspections: the battery must be correctly charged, never use a power source greater than 16 V, never use a tell-tale light. 10 Chapter 1 D - OPERATIONS ON MECHANICAL COMPONENTS Never place the transmission on the ground unprotected. The converter retaining pin must be inserted when the transmission is removed. The centring pin must be used to couple the transmission to the engine. Remove the centring pin just before coupling the transmission to the engine. 11 Chapter 2 SELECTOR CONTROL I - SELECTOR LEVER The selector lever, through the selector shaft (on the transmission), operates the multifunction switch and the manual valve on the hydraulic distributor. D A B E C RI AL4007D A - Upper part B - Lower part C - Sleeve stop D - Control lever E - Locking plunger for the Shift-Lock function Ri - Initial setting 12 Chapter 2 The selector lever, located on the central console, has six positions laid out on an offset or stepped grid. The lever has a mechanical safety device which is unlocked by exerting a radial action on the lever. Note: The ignition must be switched on and the brake pedal pressed to unlock the selector lever from position P. This is the Shift-Lock function. C Ri G C - Sleeve stop Ri - Initial setting G - Control return with ball joint AL4028C 13 Chapter 2 II - PROGRAM SELECTOR This is located on the central console next to the selector lever and has 3 push buttons. The driver can therefore inform the ECU of his selection: desired program, 1st imposed this is obtained by pressing the 1 button of the selector with the selector lever in position 2 on the grid. P R N D N D 3 2 AL4006C Gears change automatically depending on vehicle speed and engine load in accordance with various gear changing laws. The gear changing laws are chosen by the ECU as a function of one of the three programs available to the driver. The driver can select a program by pressing one of the S or * program selector buttons. 14 Chapter 2 The following three programs are available: autoadaptive or normal (no buttons pressed): this is the basic program; the ECU adjusts the operation of the automatic transmission to the style of driving, the road and engine load; it promotes fuel economy, Sport (S button pressed): this program promotes sporty driving to the detriment of consumption. Gears are still changed automatically, Snow (* button pressed): this program is suited to driving on low adherence ground. In drive, this means that either first gear or first and second gears are no longer available and gears are changed down less frequently using a specific set of changing laws. Furthermore, in the imposed positions 1, 2, 3, the Snow set of laws are used which take into account the restrictions relating to the chosen imposed position. Note: Every time the ignition is switched off then on again, the ECU automatically switches to the normal program configuration. 15 Chapter 3 CHECKING THE OIL LEVEL Check the oil level every kms. Prerequisites: vehicle on horizontal ground, check that the transmission is not in downgraded mode, remove the filler plug 1 and systematically add 0.5 litres of oil to the transmission, press the brake and change through all the gears, selector lever in position P, engine running at idle speed, + 8 oil temperature 60 C AL4008C AL4009C Filler plug 2 - Transmission housing 3 - Level plug 4 - Drain plug 2 3 AL4010C 16 Chapter 3 Remove the level plug (3). If oil streams out then starts to drip close the level plug and tighten to 2.4 mdan. If oil drips out or does not flow at all close the level plug (3), stop the engine, add 0.5 litres of oil to the transmission, repeat the level checking procedure, the oil level is correct if oil streams out and then starts to drip, close the level plug (3) and tighten to 2.4 mdan close the filler plug (1) and tighten to 2.4 mdan Too much oil may have the following consequences: abnormal heating of the oil, oil leaks. Too little oil may damage the transmission. Note: An oil check is not included in the PDI nor the first service. 17 Chapter 4 THE TORQUE CONVERTER The AL4 automatic transmission is fitted with a standard torque converter which has an added lock-up device. I - DESCRIPTION Lock-up piston 2 - Double sided friction plate 3 - Vibration damper 4 - Impeller 5 - Turbine 6 - Stator 7 - Free wheel 8 - Oil pump drive 9 - Automatic transmission input shaft drive Starting ring AL4011P Drive end plate 3 Converter AL4027C 5 4 18 Chapter 4 The torque converter consists of: an impeller (4), linked to the engine, a turbine (5), linked to the transmission, a stator (6), fitted on the free wheel (7) and located between the impeller and the turbine, a lock-up device operated by the ECU which consists of a piston (1), a friction plate (2) and a vibration damper (3). The converter is secured to the engine drive plate (end plate). Its role is to provide a flexible and automatic link between the engine and the transmission. It has two operating phases: the converter phase where it multiplies the engine torque by up to 2.2 times, the coupling phase where it transmits the engine torque with an efficiency of 0.98 (1 if it is locked up). II - CONVERTER LOCK-UP A - GENERAL The clutch is hydraulically operated by an electrovalve controlled by the ECU. The clutch can be in one of two states: open state normal converter operation, closed state where it connects the impeller and the turbine so as to transmit all of the engine torque engine brake available, reduction in fuel consumption, cooling of automatic transmission oil. Lock-up is available on 2nd, 3rd and 4th gears (and 1st gear in rare cases). The converter is locked up by inverting the direction of oil flow. The ECU controls the two possible states of the lock-up using a set of memorised laws. 19 Chapter 4 B - OPERATING PRINCIPLE OF THE LOCK-UP The lock-up piston (1) is used to connect the impeller (4) to the turbine (5) via the vibration damper (3) and the friction plate (2). 1 - Converter not locked up 1 AL4012D a In the unlocked mode, oil pressure arrives through the lock-up circuit (a) so as to free to lock-up piston from the clutch plate. The oil then supplies the converter and the spring through the converter circuit (b). 5 b Converter locked up In the locked mode, the lock-up circuit (a) is connected to tank. The oil therefore arrives through the converter circuit (b) into the converter causing the lock-up piston to move. This allows the turbine to connect with the impeller via the vibration damper and double sided clutch plate. AL4013D Note: The lock-up piston is joined to the rotating impeller. 20 Chapter 4 21 Chapter 5 THE EPICYCLIC GEAR TRAIN I - DESCRIPTION To provide the four forward gears and one reverse gear, the AL4 automatic transmission has a SIMPSON type epicyclic gear train. This consists of two simple epicyclic gear trains connected together. There are: two sunwheels P1 and P2, two sets of planet wheels S1 and S2, two planet wheel carriers PS1 and PS2, two rings C1 and C2. The two gear trains are connected in the following manner: planet wheel carrier PS1 and ring C2 are connected together, planet wheel carrier PS2 and ring C1 are connected together. Gear train n 1 is located on the rear housing side. Gear train n 2 is located on the converter side; the movement systematically exits through its planet wheel carrier PS2. E1 F1 F2 F3 C2 S2 E2 C1 S1 P2 P1 PS1 Primary pinion of the step down gear Movement input housing PS2 AL4014D 22 Chapter 5 Secondary pinion of the step down gear P2 C2 PS1 P1 Connection with PS1 PS2 C1 AL4015P Primary pinion of the step down gear Gear train specifications Sunwheel P1 Sunwheel P2 Planet wheel S1 Planet wheel S2 Ring C1 Ring C2 33 teeth 40 teeth 21 teeth 19 teeth 81 teeth 80 teeth 23 Chapter 5 II - OPERATING PRINCIPLE 1st gear F1 F2 F3 E1 E2 C1 PS1 C2 PS2 PP des Lock-up P1 P2 PP des = Primary step down pinion AL4016D Primary 2nd gear F1 F2 F3 E1 E2 C1 PS1 C2 PS2 PP des Lock-up P1 P2 PP des = Primary step down pinion AL4017D Primary 24 Chapter 5 3rd gear F1 F2 F3 E1 E2 C1 PS1 C2 PS2 PP des Lock-up P1 P2 PP des = Primary step down pinion AL4018D Primary 4th gear F1 F2 F3 E1 E2 C1 PS1 C2 PS2 PP des Lock-up P1 P2 PP des = Primary step down pinion AL4019D Primary 25 Chapter 5 Reverse F1 F2 F3 E1 E2 C1 PS1 C2 PS2 PP des Lock-up P1 P2 PP des = Primary step down pinion AL4020D Primary Table of moving parts GEAR DRIVING COMPONENT REACTION COMPONENT RATIO 1 P1 P PS1 - C2 P P1 and PS1 - C2 none 1 4 PS1 - C2 P Reverse P1 PS1 - C2 2.45 26 Chapter 5 27 Chapter 6 ECU The ECU of the AL4 transmission is an autoadaptive and upgradable ECU with a 56 track Flash Eprom. I - ECU FUNCTIONS The ECU performs the following functions: A - GEAR CHANGING LAWS The ECU has 10 gear changing laws allowing the operation of the transmission to be altered to the driver's style of driving, to the chosen program and to the internal and external conditions. The following laws are therefore obtained: 6 laws: for autoadaptivity, 1 law: for the snow program, 1 law: unlocked for low temperature operation, 1 law: for depollution when cold (heating), 1 law: for automatic transmission temperature protection. B - PROGRAMS The ECU manages three programs: autoadaptive, Sport and Snow (upon driver's request). C - AUTO-ADAPTIVENESS The ECU has an autoadaptive program which allows it to chose the law which will be the best suited to the following conditions from the ten laws listed above: driver's style of driving 3 laws = economic , Medium , Sport , road profile and vehicle load 3 laws = slight incline (or braking 1 ), sharp incline (or braking 2 ), decline , temperature, selected program. 28 Chapter 6 D - GEAR CHANGE UP PREVENTION DUE TO SUDDEN REMOVAL OF FOOT FROM ACCELERATOR This function prevents the transmission from changing up to a higher gear when the foot is suddenly removed from the accelerator pedal; this allows the engine brake to be maintained whilst decelerating. E - GEAR LOCKING FOLLOWING A LAW CHANGE For reasons of safety and comfort, the transmission is prevented from changing up or down a gear too quickly if the law has just changed. F - CHANGE DOWN The ECU is totally responsible for changing down the gears as a function of engine load, vehicle speed and driving conditions. The ECU authorises a double change down (from 4th to 2nd and 3rd to 1st) or forces a single change down. Furthermore, the ECU provides a change down function in the event of sustained braking in order to anticipate downward gear changes and so as to provide the engine brake. G - MOMENTARY SWITCH TO SPORT PROGRAM So as to provide better power take-up in the normal program, the ECU temporarily switches to a more sporty law when the accelerator pedal is suddenly pressed down. H - KICKDOWN The kickdown order is given by the automatic transmission ECU after the accelerator pedal is pressed down fully and depending on vehicle speed. I - MANAGEMENT OF IMPOSED GEARS The ECU is totally responsible for changing to imposed gears in terms of operation and safety (changing limits). J - CONTROLLING THE LINE PRESSURE The ECU works out the value of line pressure with closed loop feedback. The reference value is a function of the turbine torque to overcome. 29 Chapter 6 K - MANAGING GEAR CHANGES When the ECU decides to change a gear, it must operate the various electrovalves involved in a precise order and in accordance with timers which are a function notably of the engine load and vehicle speed. This provides a good overlap between the receiver which is emptying and the one which is filling up. L - OPERATING THE CONVERTER LOCK-UP CLUTCH This function optimises the converter operation by locking it up to save fuel, to obtain engine braking, to encourage cooling of the transmission oil and to prevent slip. A law which
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