23 · Diagnostics

Poor braking action

Make: Alfa Romeo
Model: 159 Factory Service Manual
Year: 2005–2011
Section: Brakes › Poor braking action

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Fault diagnosisPoor braking action

POOR BRAKING ACTION

As the pressure exerted on the brake pedal increases, there is no noticeable corresponding braking action

0	PRELIMINARY CHECKS	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	First of all, check that the tyres are the correct type, in good condition and correctly inflated	Move on to Step 1	1. Pressure not correct	1. Make sure tyres are inflated to the correct pressure.
		Move on to Step 1	2. Tyres unsuitable or worn	2. Replace the tyres.
1	BRAKE FLUID LEAK CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Visually check: The level of the brake fluid in the reservoir; No fluid leaks from the brake pump, the pipes or the system connectors	Move on to Step 2	Leaks in the system.	Tighten the connectors or replace the damaged parts, see Assembly Op. 3340B ABS SYSTEM PIPES
2	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Connect the diagnostic test equipment (Examiner or other instruments) to the tester input. Check that there are no faults in the ABS control unit.	Move on to Step 3	1. Error detected in the control unit.	1. Continue following the instructions for the diagnostic equipment
		Move on to Step 3	2. No communication with the control unit.	2. Restore: Connection between the ABS control unit and the diagnostic connector; ABS control unit supply See E7020 ABS See E7020 ABS
3	ACTIVE DIAGNOSIS WITH DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Connect the diagnostic equipment (Examiner or other instruments) and carry out the active diagnosis for: Pump motor; Solenoid valves.	Move on to Step 4	Fault detected in the pump or in a solenoid valve.	Replace the electrohydraulic unit - ABS electronic control unit Op. 3340A12 ABS HYDRAULIC AND ELECTRONIC CONTROL UNIT - R.R.
4	CHECK ON TYPE OF PADS AND SURFACE	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check: Condition of the braking surfaces and pads. Type of pads.	Move on to Step 5	1. Brake surfaces vitrified or with traces of grease, oil or water	1. Clean again, check and remove the causes of the fault
			2. Front pads damaged or not the recommended type	2. Replace the front pads Op. 3310A60 FRONT BRAKE PADS - REPLACE
			3. Rear pads damaged or not the recommended type.	3.Replace the rear pads Op. 3310B62 REAR BRAKE PADS - REPLACE
5	CHECK DISCS	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the condition of the brake discs.	Move on to Step 6	1. Front discs worn or damaged.	1. Regrind the discs or, if necessary, replace them Op. 3310A54 FRONT BRAKE DISCS REMOVED - GRIND Op. 3310A52 FRONT BRAKE DISCS - R+R WITH BRAKE CALIPERS REMOVED
	Check the condition of the brake discs.	Move on to Step 6	2. Rear discs worn or damaged.	2. Regrind the discs or, if necessary, replace them Op. 3310B54 REAR BRAKE DISCS REMOVED - GRIND Op. 3310B52 REAR BRAKE DISCS - R+R WITH BRAKE CALIPERS REMOVED
6	BRAKE CALIPER CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the condition of the front and rear brake caliper pistons.	Move on to Step 7	1. Front caliper pistons worn or seized.	1. Replace the front brake calipers. Op. 3310A32 FRONT BRAKE CALIPERS - R.R.
		Move on to Step 7	2. Rear discs worn 2. Rear caliper pistons worn or seized.	2. Replace the rear brake calipers. Op. 3310B34 REAR BRAKE CALIPERS - R + R - INCLUDES HANDBRAKE ADJUSTMENT
7	VACUUM PIPE CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check that the vacuum pipe is correctly fitted/in good condition.	Move on to Step 8	1. Pipe not fitted correctly or bent.	1. Fit correctly
		Move on to Step 8	2. Pipe damaged.	2. Replace vacuum pipe Op. 3330D24 VACUUM PIPE FOR BRAKE SERVO - R+R
8	BRAKE SERVO SINGLE-ACTING VALVE CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check that the brake servo single-acting valve is working properly.	Move on to Step 9	Single-acting valve not working properly.	Replace the single-acting valve Op. 3330D20 SINGLE-ACTING VALVE FOR BRAKE SERVO - R+R
		Move on to Step 9	Single-acting valve not working properly.		9	BRAKE SERVO CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check that the brake servo is working properly, see Test See Test 3330DA CHECK VACUUM PUMP OPERATION AND BRAKE SERVO VACUUM CIRCUIT	Move on to Step 10	Brake servo not working properly.	Replace brake servo Op. 3330D10 BRAKE SERVO - R+R - INCLUDES SEPARATION FROM MASTER CYLINDER (PUMP)
		Move on to Step 10	Brake servo not working properly.		10	ENGINE VACUUM CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the vacuum circuit reading.	Move on to Step 11	Vacuum figure not correct.	Replace the brake servo vacuum unit Op. 3330D30 VACUUM PUMP - R+R
	Check the vacuum circuit reading.	Move on to Step 11	Vacuum figure not correct.		11	CHECK ON FLEXIBLE BRAKE PIPES AND BLEEDING	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Visually inspect that there are no bends or constrictions in the brake pipes, bleed the system and check that the fluid comes out evenly from the bleed screws. Op. 0010T65 HYDRAULIC BRAKE SYSTEM - BLEED AIR	End of diagnosis	Bends or constrictions present, the fluid does not come out evenly.	Replace the section of pipe affected by the problem, see Assembly Op. 3340B ABS SYSTEM PIPES

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Parts & tools for this job Staging For 2005 Alfa Romeo 159

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