2006 LAND ROVER FRELANDER 2 lock

Publi s hed: 11-May-2011
Ride and Handling Optimization - Ride and Handling Optimization
Diagnosi s and Tes ti ng
Principles of Operation
For a detail ed descripti on of the Terrain Respons e s ys t em, refer t o t he rel evant Descript ion and Operat ion secti on in theworks hop manual .REFER to: Ri de and Handl ing Opt imi zat ion (204-06 Ri de and Handl ing Opt imizati on, Des cript ion and Operat ion).
Inspection and Verification
CAUTION: Di agnos is by s ubs ti tut ion from a donor vehicle is NO T acceptabl e. Subs ti tut ion of cont rol modules doesnot guarant ee confirmat ion of a faul t, and may als o caus e addit ional fault s i n t he vehi cl e being t est ed and/or t he donorvehi cl e.
1. Verify t he cus t omer concern.1.
2. Vis ually ins pect for obvious s igns of mechani cal or electrical damage.2.
Visual InspectionMechanicalElectrical
* Ti re condit ion, pres sures, et cDriveline, Engine, Transmis s ion, Sus pensi on,component s (correct ins tall ati on, damage, etc)
Fus esHarness es /Connect orsTerrai n res pons e modul eEngi ne Cont rol Module (ECM)Transmis s ion Control Modul e (TCM)Ant i-Lock Brake Sys t em control modul eAct ive On-demand cont rol moduleDynami c s us pensi on cont rol module * Controllerarea network (CAN) ci rcuit s
3. If an obvious cause for an obs erved or report ed concern is found, correct t he caus e (if pos s ible) beforeproceeding t o t he next s t ep.3.
4. If t he caus e is not vis ually evi dent , check for Di agnos ti c Trouble Codes (DTCs) and refer t o t he DTC Index.4.
DTC Index
• NOTE: If the control modul e/t rans mis s ion i s s uspect and the vehicle remai ns under manufacturer warrant y, refer t o t heW arranty Pol icy and Procedures manual (s ect ion B1.2), or determine i f any pri or approval programme is in operat ion, pri ort o the ins tall ati on of a new module/transmis s ion.
• NOTE: Generic scan t ool s may not read the codes li st ed, or may read only fi ve digit codes . Mat ch the five di git s from t hes can tool to the firs t fi ve di git s of the seven digi t code l is ted to ident ify t he faul t (t he las t t wo digi ts gi ve addi ti onalinformat ion read by the manufact urer approved diagnos t ic s ys tem).
• NOTE: W hen performing el ect ri cal volt age or resi s tance tes t s, al ways us e a digit al mult imet er (DMM) accurate to threedeci mal places , and wi th an up-to-date cali brat ion cert ificate. W hen t es ti ng res is t ance, always take t he res i st ance of t heDMM leads int o account.
• NOTE: Check and recti fy bas ic faul ts before beginni ng diagnos t ic rout ines i nvol vi ng pinpoint t es t s.
• NOTE: Ins pect connect ors for s igns of water ingres s , and pins for damage and/or corros ion.
• NOTE: If DTCs are recorded and, aft er performi ng the pi npoi nt tes ts , a fault is not present , an int ermi tt ent concern maybe t he caus e. Always check for loose connect ions and corroded terminals .
For a compl ete lis t of all Di agnos ti c Trouble Codes (DTCs) t hat could be logged on this vehicle, pleas e refer to Sect ion100-00.
REFER to: Di agnos ti c Trouble Code (DTC) Index - DTC: Terrain Res pons e Cont rol Modul e (ATCM) (100-00 GeneralInformat ion, Des cript ion and Operat ion).

Not s ens it ive to brake tes ti ng on a chas si s dynamomet er.
Generati on 4 Acti ve On-Demand Coupli ng - Vehicles from 2009MY
The generati on 4 coupl ing does not have the di fferenti al s peed dri ven pump used on the previ ous generat ion 3coupl ing, but i s fit ted wi th a bigger capacit y electrically operated axial pump and a hi gh pres s ure accumul ator.The proport ional throt t le valve and press ure s ens or on t he generat ion 3 coupli ng is replaced wit h a proport ionalpres s ure reducing val ve.The t orque li mit er pres sure reducing valve on the generat ion 3 coupli ng is replaced by an electroni c cont rol valveand cont rol ling software.
The generati on 4 acti ve on-demand coupli ng gives t he fol lowing improvements over t he previous generati on 3 coupl ing:
Reduced bas e t orque at high different ial s peedsTorque acti vat ion i s now i ndependent of different ial s peedAccurat e t orque l imi ter cont rolEnergy s tored in hi gh pres s ure accumul ator givi ng a low maximum current consumpt ion of t he electric pump andfas t er res pons e.
Control Module - G eneration 3 and 4 Couplings
The cont rol module, at tached to the cas ing of t he act ive on-demand coupling, forms a s ingle unit wit h t he cont rolvalve/axial s ol enoi d. By anal yzi ng informat ion from other vehi cl e modules and s ensors t he cont rol module regul ates t heaxial sol enoi d t o cont rol t he hydraul ic flui d pres s ure s uppl ied t o t he clut ch pl ates. Some of t he modul es and s ens ors thecont rol module communi cat es wit h are li s ted below:
Hardwi red:- Control valve / axi al s olenoid- Electric hydrauli c pump- Oi l press ure and temperat ure sens orHigh speed CAN (cont rol ler area net work):- Engine cont rol module- Anti -l ock brake s ys t em / t racti on cont rol module- Tracti on res ponse swit ch- Y aw rate sens or- Steering wheel rot at ion sens or
The axial sol enoi d cons t ant ly adjust s t he cont rol valve output us ing a Pul se W i dt h Modulat ion (PW M) s i gnal. The flui dpres s ure deli vered t o t he cl utch plat es determines t he amount of t orque t hat is delivered t o t he rear axl e.
The act ive on-demand coupli ng has int egrated oi l press ure and temperature s ens ors to enable the control modul e t oaccurat ely manage t he t orque t ransfer under all environment al and operat ing condit ions . Usi ng thes e s ignals the controlmodule will us e s t rategi es to protect the coupli ng from overheati ng; in extreme cas es to protect t he coupli ng from damaget he coupli ng wil l dis engage i f the t emperat ure of t he hydraul ic flui d exceeds 105°C. The coupl ing wi ll ret urn to normalfuncti onal it y when t he temperat ure fall s below 101°C.
The cont rol module has an int egrated di agnos ti cs sys tem, whi ch cons tant ly moni tors the act ive on-demand couplings ys t em as wel l as it s input and output s ignals . If t he control modul e detects a fault a Diagnost ic Troubl e Code (DTC) i ss tored. The DTC is acces s ed usi ng t he Land Rover approved di agnos t ic s yst em.
Electric Hydraulic Pump
W hen negoti ati ng very low frict ion s urfaces s uch as wet gras s , snow or i ce; i nit ial wheel -s pin can cut i nt o t he s urface andreduce gri p. W it h a re-act ive on-demand coupl ing, almos t 60 degrees of wheel rotat ion woul d occur before torque could bet ransmit ted t hrough t he coupl ing.
On Generat ion 3 coupli ngs , t o count eract thi s Land Rover devel oped a uni que high-pres s ure pre-charge faci li ty whi chenergizes t he hydraul ic circui t as s oon as the engi ne is s t art ed. Es s ent ial ly an el ect ri cal ly operat ed hydraul ic pump wasdesi gned to maintai n a pot ent ial of 500 Nm (369 l b ft ) of t orque pres s ure wi thi n the coupli ng. (This pre-charge t orquecapacit y has been increas ed to 1500Nm (1106 l b ft ) for t he Generat ion 4 coupli ng.)
Vehicles fit ted wi th Terrai n Res pons e als o add furt her benefi ts by varying t he level of pre-charge t o deli ver opti mumt racti on over a range of di fferent t errai n s urfaces . The level of pre-charge is varied dependi ng on t he part icul ar terrainres ponse mode, for exampl e:
Terrai n respons e in 'Speci al Programs Off' mode as common wit h vehi cl es wit hout terrain res pons e, the coupli ng isprogrammed t o transmit 500 Nm 369 lb ft of t orque on Generat ion 3 couplings and 1500 Nm (1106 l b ft) of t orqueon Generat ion 4 couplings t o t he rear axle when the vehicle moves from res t i n a s t raight l ine. Thi s s trategymi ni mi zes t ract ion l os s from a s t andi ng-s tart regardles s of t he terrain. W hen the vehicle accelerat es the pres surein the coupling is decreas ed to improve fuel economy.The abili ty to sens e t he s teeri ng angl e all ows t he coupli ng t o be programmed t o provide no torque trans fer t hrought he coupli ng. This prevent s t he coupli ng locking when t he vehicle i s maneuvring at low s peeds and acute s teeri ngangl es.In 'Grass / Gravel / Snow' mode t he coupl ing i s programmed to maint ai n i ts pre-charge s t at e unt il much highers peeds are obtained. The s ame applies even i f the vehicle is t raveli ng at low speeds and acut e s t eering angles , ast racti on takes precedence over coupli ng lock-up on l ow-fri ct ion s urfaces .
For addit ional informat ion, refer t o: Ride and Handli ng Opti mizat ion (204-06 Ride and Handli ng Opt imi zat ion, Descripti onand Operat ion).
Mechanical Hydraulic Pump - Generation 3 Couplings - Vehicles up to 2009MY
The dri ves haft i s att ached t o t he coupl ing's front clut ch pl ate as s embly (i nput ), with the rear cl ut ch plat e as sembl yconnected t o t he different ial pini on (out put ). A s was h-pl ate wit h 6 hydrauli c rol lers is al so att ached t o t he different ialpinion. W hen there is no s peed difference bet ween the coupling's input and out put, the rol lers do not funct ion.

However, when the front and rear axl es st art t o rotat e at different s peeds , t he s wash-pl ate rot at es rel ati ve to the roll erswhich generat es the hydrauli c pres s ure. Thi s pres s ure i s us ed to force the opposi ng clut ch pl ates t oget her, i ncreas ing thet ransmis s ion of t orque t o the rear axl e. As the di fference in axl e s peed i ncreases the hydrauli c pres sure pushes t he clut chplat es further together t o increas e t he t orque to the rear axl e.
A control val ve/axi al s olenoid cont rols the amount of pres s ure appli ed to the clut ch plat es , and hence the amount oft orque transmit ted t o t he rear wheels . Clos e manufact uring t olerances and except ional ly low component wear ens uret orque cont rol remai ns accurat e t hroughout t he vehi cl e's l ife.
Mechanical Hydraulic Pump - Generation 4 Couplings - Vehicles from 2009MY
The Generati on 4 coupl ing does not us e the swas h pl at e t o mechanical ly rais e hydrauli c pres s ure; ins tead, a new hydraul icpump i s used to generat e hydrauli c pres sure and force the cl utch plat es toget her. The removal of t he s was h plat e all ows alarger overal l cl ut ch plat e s urface area, whi ch in t urn reduces t he hydrauli c pres sure requi rement. The press ure required toachi eve 1500Nm (1106 l b ft ) has been reduced from 100 Bar for Generat ion 3 coupli ngs to 40 Bar for Generati on 4coupl ings.
The posi ti oni ng of the Generat ion 4 coupl ing's i nput and output remains t he s ame as t he Generati on 3 coupl ing, asdescribed above.
By-pass Valve
On very low fricti on s urfaces, driveli ne drag t orque can occur, for exampl e:
revers e t orque from engi ne braking, orforced movement of t he dri ves haft by t he front wheel s .
This can i nfluence rear wheel s peed, maki ng it i mpos si ble t o determine the t rue fricti on capabil it y of the rear wheel s, bydis t orti ng t he wheel s peed s ignal. To prevent thi s, t he acti ve on-demand coupli ng is des i gned t o open i mmediat el y inres ponse to a s tabil it y cont rol event . This i s achi eved by a by-pass val ve ins tant ly reducing sys tem pres s ure t o nomi nal .
To balance the 4 bar bas e press ure (s ee below for detai ls ), t he Generati on 3 coupling us es a large Bel levill e s pri ng to forcet he cl utch plat es clear of each ot her t o prevent torque transmis si on t hrough the coupli ng. Even at 0°C, t orque t rans mis s ionis reduced from 300 Nm to Zero wi thi n 10 ms . The Generat ion 4 coupling however, does not require a Bel lvil le s pri ng t os eparate t he plat es as t he coupli ng does not have a si gni fi cant bas e pres s ure pus hi ng t he plates together.
Accumulator
The further t he cl utch pl at es have to move in order to contact each other, t he longer it t akes to di spl ace the hydrauli c fl uidneces s ary t o buil d pres s ure and t rans mit torque. To count er thi s, t he Generati on 3 coupling incorporates an accumulat or.This retains a nominal 4 bar pres sure wi thin the hydraul ic circui t. Al though thi s is not enough pres sure t o caus e s i gni fi cantt orque transmis s ion t hrough the coupli ng, i t forces t he plat es very clos e t oget her so that very l it tl e fluid di s pl acement i srequired t o achi eve full engagement and maxi mum t orque t rans fer. Ful l torque t rans miss i on can be achieved i n 150 ms .
On Generat ion 4 coupli ngs , t he 150ms act ivat ion t ime is achieved through the us e of a Bel lvil le s pri ng t hat acts to pus ht he plates t ogether (wi thout caus i ng si gnifi cant t orque t rans mis s ion t hrough t he coupl ing). As t he pump i s notcont inuousl y us ed to create t his bas e pres s ure (as i t was wit h Generat ion 3 coupli ng), improvement s i n fuel economy havebeen achi eved.
Wet Clutch Pack
The clutch pack is made up of 7 pairs of plat es ; t he inner dis cs are produced from hardened st eel wit h t he out er dis csmanufactured from s t eel wi th a s int ered face. The clutch pl ates operat e in trans mi s si on fl uid.
Torque t rans mis s ion acros s t he clutch pack is li mit ed t o 1500 Nm (1106 lb ft ). This ens ures t he l ower gears ret ai n anelement of front-wheel -drive for t ract ion s t abi lit y. W i thin the hi gher gears the coupl ing i s t heoreti call y capabl e oft ransmit ti ng all t he dri ve to the rear axle; al though condit ions woul d have to be ext reme for t his t o occur.
PRINCIPLES OF OPERATION
Generation 3 Couplings - up to 2009MY
An i nt ernal electroni cal ly-controll ed pump provides hydrauli c pre-charge pres sure wit hin the coupling. The pre-chargepres s ure s upplies t he requi red operat ing pres s ure to the clut ch plates to el imi nat e i nit ial wheel -s pin as the vehicleaccelerates from s tandst il l.
In conjunct ion wi th the pre-charge pres s ure a mechanical hydraul ic pump operates wi thi n the cl utch plat es to s upply thecoupl ing's mai n hydraulic operat ing pres sure. The mechanical pump is funct ioned by the 'i nput ' and 'output' of t he coupli ng:
input - dri ves haft connect ion from the front axle,output - different ial connecti on to the rear axl e.
Any s peed di fference bet ween t he front and rear axl es wil l st art t he operat ion of t he mechanical hydraul ic pump. Theamount of hydrauli c pres s ure appli ed to the cl ut ch pack by the pump det ermines the gap bet ween t he cl utch plat es. Forexampl e, the great er the hydraul ic pres s ure, t he s maller t he gap between t he plat es and s ubs equent ly t he great er thet orque transmit ted t hrough t he coupli ng from the front axle t o t he rear axle.
This mai n hydrauli c pres sure is des i gned t o t rans mit the t orque for tract ion demands of off-road drivi ng, and t o provi delock-up as requi red.
Generation 4 Couplings - from 2009MY
The Generati on 4 coupl ing s t il l us es an el ect ri cal ly-controlled pump to provide hydrauli c pre-charge to el imi nat e wheel-s pinfrom st ands t il l; however, the s ame pump is al s o used to provi de t he coupli ng's mai n hydraul ic operat ing press ure.

16. CAUTION: It is es s ent ial t hat abs olut e cleanl ines s isobs erved when working on the rear different ial. Al ways cover anyopen ori fi ces us ing lint free non-flocking mat eri al t o prevent t hei ngress of foreign matt er. Fail ure t o follow thi s ins truct ion mayres ult damage t o t he component s.
Remove t he different ial from t he s upporti ng tool .Thoroughl y clean t he pinion shaft paying parti cul ar at t ent iont o t he thread.Us ing a s ui table cl eani ng fl uid t horoughly clean t hedifferent ial casi ngs .
16.
Installation
1. CAUTION: Do not clean or l ubricate the newpini on s haft tai l bearing, as it i s s uppl ied coat ed wi th al ow frict ion oil . Fai lure t o fol low t his ins truct ion wi llrequi re t he pini on s haft tai l bearing t o be repl acedbefore t he different ial can be succes s ful ly as s embled.
Secure t he different ial cas i ng to the s peci al tool.Us ing a s ui table pres s and t he special t ooli ns t all the pi nion s haft t ail bearing out er race.
1.
Inst all t he new pini on shaft spacer.2.

6. W ARNING: High t orque applicat ion.
• CAUTIONS:
The s peci al tool s hould be t urned count erclockwis e t o ins t al l the pi nion s haft nut.
Do not us e ai r tools to i nst all t he nut. Fail ure t ofol low thi s ins truct ion may res ult i n damage t o thecomponent .
• NOTE: 250 Nm (184 lb.ft) i s t he mi ni mum torquerequi rement to begi n collaps ing t he pini on s haft s pacer.
Us ing t he s peci al t ools i nst all t he new pini onnut.Tight en to 250 Nm (184 ib. ft).
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7. CAUTIONS:
Make s ure the specified t orque t o rot ate thepini on s haft is not exceeded. If exces s prel oad isapplied to the joint t he pinion s haft s hould be removedand a new col lapsi ble s pacer, pinion shaft tail beari ng,pini on s haft tai l bearing cup and pinion nut mus t bei ns t alled.
The s peci al tool s hould be rot ated at 60 rpm (1xrevolut ion per s econd) t o produce a cons i st ent reading.
The pi ni on s haft s houl d be rotat ed through t woful l revolut ions by hand before the t orque meas urementi s performed.
Us ing t he s peci al t ool, check t he t orque requiredt o rot ate the pi nion s haft . The specified t orquei s 1.1 Nm +/- 0.2 NmIf the s pecifi ed t orque t o rot ate the pi ni on s hafti s not reached, usi ng t he s pecial t ool s, t ight ent he pinion flange nut in one degree increment sand check t he rot ati onal t orque after each unt ilt he s pecified t orque of 1.1 Nm +/-0.2 Nm i sachi eved.
7.
8. CAUTION: Do not l ubricate the pi ni on oil s eal.
Us ing a s ui table pres s, t he s peci al t ool and adapt eri ns t all the pi nion beari ng oil s eal .
8.Inst all t he crown wheel ass embly.9.

The parking brake is a manual ly appli ed cabl e s ys t em t hat operates brake s hoes, housed wit hin the i nner diamet er of eachrear brake di sc.
FRONT AND REAR DISC BRAKES
The 3.2L i 6 vehicle i s ins t al led wit h vent il ated front and rear brake di scs . The 2.2L TD4 vehicle is i nst all ed wit h venti latedfront and sol id rear brake dis cs. Bot h t he i6 and TD4 vehicl es feature s ingle pi s ton, s lidi ng cal ipers on all brake dis cs . Foraddi ti onal i nformat ion, refer to:
Front Dis c Brake (206-03 Front Di sc Brake, Des cri pt ion and Operati on),Rear Di sc Brake (206-04 Rear Di s c Brake, Des cri pti on and Operati on).
PARKING BRAKE
The parking brake is a manual ly appli ed, cable operat ed s yst em. The RH and LH rear brake dis cs form the parki ng brakedrums , and provide the l ocat ion for the parki ng brake s hoes and components .For addit ional informat ion, refer t o: Parking Brake (206-05 Parki ng Brake and Act uat ion, Descripti on and Operat ion).
HYDRAULIC BRAKE ACTUATION
Hydrauli c brake act uati on cons is t s of the brake pedal , mast er cyl inder, HCU, and t he connect ing hydraul ic pipes and hos es.
The t andem brake mas ter cylinder wit h reservoi r is at tached to, and operat ed by t he brake boos t er. The brake mas t ercyl inder is a tandem des ign t hat suppli es pres s ure t o 2 i ndependent (pri mary and secondary) hydraul ic circui ts .For addit ional informat ion, refer t o: Hydraulic Brake Actuati on (206-06 Hydraulic Brake Act uati on, Des cri pt ion andOperat ion).
BRAKE BOOSTER
The brake boost er is vacuum operat ed and provides power as s is t ance t o t he brake hydrauli c s ys t em. The boos t er i s oft andem des ign that incorporat es 2 s eparate diaphragms . On both the gas oline and di esel models , t he vacuum required forboos t er operat ion is produced by an engine driven, vacuum pump.For addit ional informat ion, refer t o: Brake Boos ter (206-07 Power Brake Act uati on, Des cript ion and Operat ion).
ANTI-LOCK CONTROL
The anti -l ock control sys tem feat ures a Cont inental Teves Mk25E1 ABS module wit h i ntegral 4 channel HCU. The ABSmodule and HCU provide brake sys tem monit ori ng, and acti ve brake funct ions t o cont rol t he vehi cl e s tabil it y and t racti on.The ABS module al s o provides s peci fi c functi ons to as s is t t he vehi cl e duri ng off-road drivi ng.
The anti -l ock control sys tem provides t he fol lowing funct ions :
Anti -l ock Brake Sys t em (ABS)Corner Brake Control (CBC)Dynamic St abi li ty Cont rol (DSC)Electroni c Brake Force Di s tributi on (EBD)Electroni c Tracti on Control (ETC)Emergency Brake As s is t (EBA)Engi ne Drag-Torque Control (EDC)Hil l Descent Cont rol (HDC) wit h gradi ent release cont rolRoll Stabi lit y Control (RSC)Terrai n Res pons e™ sys tem int egrati on.
For addit ional informat ion, refer t o: Anti -Lock Cont rol - St abi li ty As s is t (206-09C Anti -Lock Cont rol - St abi lit y As s is t,Des cript ion and Operat ion).

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Is t he power brake boost er val ve OK?YesCHECK the brake boos t er. For addit ional informat ion, refer t o Brake Boos t er component t es t in t hissect ion. INSTALL a new brake boos ter as requi red.REFER t o: Brake Boos ter (206-07 Power Brake Act uati on, Removal and Ins tal lati on).TEST the s ys tem for normal operat ion.NoINSTALL a new brake boos t er valve. TEST the sys tem for normal operat ion.
PINPOINT TEST H : BRAKE LOCKUP DU RING LIG HT BRAKE PEDAL FORCE
T EST CONDIT IONSDET AILS/RESULT S/ACT IONS
H1: T EST BRAKE LOCKUPRoad t est t he vehicle and apply the brake pedal li ght ly.
Do t he brakes l ockup?YesGO to H2.NoVehicle is OK.
H2: INSPECT BRAKE PADS
Inspect brake pads for contami nat ion, correct ins t al lat ion, damage and type.
Are any concerns found?YesINSTALL t he brake pads correct ly or INSTALL new brake pads as required.REFER t o: Brake Pads (206-03 Front Di s c Brake, Removal and Ins t allat ion) /Brake Pads (206-04 Rear Dis c Brake, Removal and Inst all ati on).TEST t he s ys t em for correct operati on.NoGO to H3.
H3: INSPECT BRAKE CALIPERSInspect brake calipers for bindi ng, l eaking or s t icking.
Are any concerns found?YesINSTALL t he brake cali pers correct ly or INSTALL new brake cal ipers as required.REFER t o: Brake Caliper (206-03 Front Dis c Brake, Removal and Ins tall ati on) /Brake Cal iper (206-04 Rear Di sc Brake, Removal and Ins t al lat ion).TEST t he s ys t em for normal operati on.NoVehicle is OK.
PINPOINT TEST I : BRAKES DRAG
T ESTCONDIT IONSDET AILS/RESULT S/ACT IONS
I1: ROAD T EST VEHICLE
Road t es t t he vehi cl e and apply t he brakes .
Are the brakes funct ioning correct ly?YesVehicle i s OK.NoGO to I2.
I2: CHECK BRAKE CALIPERS AND PARKING BRAKE CABLES
Check the front and rear cali per pis t ons and pins for bi ndi ng, l eaki ng or st icking and parki ng brakecabl es for s t icki ng/binding.
Do t he dis c brake cali per pi st ons and pins bind, l eak or s t ick, or t he parking brake cabl es st ick/bi nd?YesREPAIR or INSTALL new components as required. Tes t the s ys tem for normal operat ion. Road tes tvehi cle i f neces sary.NoGO to I3.
I3: CHECK BRAKE BO OST ER
Check the brake boos ter connecti ng rod alignment and t ravel.
Is the connect ing rod OK?YesVehicle i s OK.NoINSTALL a new brake boost er.REFER to: Brake Boos t er (206-07 Power Brake Actuat ion, Removal and Ins t allat ion).TEST the sys tem for normal operat ion.
PINPOINT TEST J : EXCESSIVE/ERRATIC BRAKE PEDAL TRAVEL
T ESTCONDIT IONSDET AILS/RESULT S/ACT IONS
J1: T EST ON ROUGH ROAD
Road t es t the vehicle on rough road condit ions .
Apply the brakes s l owly.
Is t he brake pedal effort and brake pedal t ravel normal?YesVehicl e is OK.NoGO t o J2.
J2: CHECK BRAKE FLUID LEVEL

brake boos ter.
5. Operate the engine for a minimum of 10 s econds at a fast i dle. Stop the engine and al low t he vehicle t o s t andfor 10 mi nut es. Then, appl y the brake pedal wi th approxi mately 89 N (20lb) of force. The pedal feel (brakeappli cat ion) s houl d be t he s ame as t hat not ed wit h t he engine runni ng. If the brake pedal feel s hard (no poweras s is t), ins t al l a new valve and t hen repeat t he tes t. If t he brake pedal s t ill feels hard, i ns t all a new brakeboos ter. If t he brake pedal movement feel s s pongy, bleed t he brake s ys t em.REFER t o: Brake Syst em Bl eedi ng (206-00 Brake Syst em - General Informati on, General Procedures ) /Brake Sys t em Pres s ure Bl eedi ng (206-00 Brake Syst em - General Informati on, General Procedures ).
5.
Brake Master Cylinder
Us ual ly, t he fi rs t and s tronges t indicat or of anything wrong i n t he brake s ys t em i s a feeling through t he brake pedal. Indiagnosi ng the condit ion of t he brake mas t er cyli nder, check pedal feel as evidence of a brake concern. Check for brakewarni ng lamp ill uminat ion and t he brake fluid level i n t he brake mas t er cyli nder reservoi r.
Normal Condit ions
The fol lowing condit ions are cons idered normal and are not i ndi cat ions t hat t he brake mast er cyl inder i s i n need of repair.
Modern brake sys tems are des igned t o produce a pedal effort that is not as hard as in the pas t . Compl aint s of lightpedal effort s s houl d be compared t o t he pedal efforts of another vehi cl e of t he s ame model and year.The fl uid l evel wi ll fal l wit h brake pad wear.
Abnormal Condi ti ons
Changes i n t he brake pedal feel or brake pedal travel are indicators t hat s omet hi ng coul d be wrong in the brake sys tem.The diagnost ic procedure and techni ques us e brake pedal feel , warning i ndi cat or il lumi nat ion and l ow brake flui d level asindicat ors t o diagnosi ng brake s yst em concerns . The foll owing condi ti ons are consi dered abnormal and indi cat e t hat t hebrake mas t er cyli nder i s in need of repai r:
• NOTE: Pri or to carrying out any diagnosi s , ens ure the brake sys tem warni ng indicator i s functi onal .
Brake pedal goes down fast . This could be caus ed by an external or int ernal leak.Brake pedal goes down s l owl y. Thi s coul d be caused by an int ernal or external l eak.Brake pedal is l ow or feels spongy. Thi s condit ion may be caus ed by no fl ui d i n the brake mas ter cylinder, reservoi rcap vent holes cl ogged or air i n t he hydraul ic s ys tem.Brake pedal effort is excess ive. This may be caus ed by a bi nd or obs t ructi on in the pedal/li nkage, a faul tynon-ret urn val ve, boost er or ins ufficient boos t er vacuum.Rear brakes lock up during light pedal force. Thi s may be caus ed by damaged brake pads , a parti ally appl ied parkingbrake, a damaged ABS s ens or or bearing fail ure.Brake pedal effort errat ic. This condit ion could be caus ed by the brake boos t er or incorrectl y ins tal led brake pads .Brake warning i ndi cat or is on. This may be caus ed by low fl uid l evel or fl oat as s embly damaged.
Non Pressure Leaks
Any reduced fl uid volume in t he brake mast er cyl inder res ervoi r may be caused by two types of none pres sure externalleaks .
Type 1: An ext ernal leak may occur at the brake mast er cyl inder res ervoir cap because of incorrect posi ti oning of t hegasket and cap. Repos it ion cap and gasket .
Type 2: An ext ernal leak may occur at the brake mast er cyl inder res ervoir mounti ng seal s. Repair s uch a l eak by ins tall ingnew s eals and make s ure that t he brake mas t er cyli nder reservoi r ret ai ning bolt i s correct ly i nst all ed.