ABS 5.4: Diagnosis Saab 9-5 I рестайлинг

FAULT DIAGNOSIS, FAULT CODES

DIAGNOSTIC TROUBLE CODES (DTC) LIST

Scheme 59

Fault symptoms

ABS warning lamp on. ABS not functioning.

Diagnostic help

1. FL wheel speed sensor signal can be read using diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Front Left".

The current wheel speed in km/h is displayed.

1. With the front of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the FL wheel is rotated by hand at a speed of about one turn a second.

Scheme 60

ABS warning lamp on. ABS not functioning.

1. FL wheel speed sensor signal can be read using diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Front Left".

The current wheel speed in km/h is displayed.

With the front of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the FL wheel is rotated by hand at a speed of about one turn a second.

1. For tracing electrical faults, the diagnostic tool can be used to take readings from the control module's wheel-sensor inputs.

1. Select "Read values"
2. Select "Wheel-sensor output"

The reading is used to determine whether there is a break in the circuit between the control module and one of the wheel sensors. If the circuit is OK, the reading should be approximately 3.4 V.

Scheme 61

ABS warning lamp on. ABS not functioning.

1. Front right wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Front Right".

The current wheel speed in km/h is displayed.

1. With the front of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the FR wheel is rotated by hand at a speed of about 1 turn a second.

Scheme 62

ABS warning lamp on. ABS not functioning.

1. Front right wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Front Right".

The current wheel speed in km/h is displayed.

With the front of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the FR wheel is rotated by hand at a speed of about 1 turn a second.

1. For tracing electrical faults, the diagnostic tool can be used to take readings from the control module's wheel-sensor inputs.

1. Select "Read values"
2. Select "Wheel-sensor output"

The reading is used to determine whether there is a break in the circuit between the control module and one of the wheel sensors. If the circuit is OK, the reading should be approximately 3.4 V.

Scheme 63

ABS warning lamp on. ABS not functioning.

1. Rear left wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Rear Left".

The current wheel speed in km/h is displayed.

1. With the rear wheels of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the RL wheel is rotated by hand at a speed of about 1 turn a second.

Scheme 64

ABS warning lamp on. ABS not functioning.

1. Rear left wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Rear Left".

The current wheel speed in km/h is displayed.

With the rear wheels of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the RL wheel is rotated by hand at a speed of about 1 turn a second.

1. For tracing electrical faults, the diagnostic tool can be used to take readings from the control module's wheel-sensor inputs.

1. Select "Read values"
2. Select "Wheel-sensor output"

The reading is used to determine whether there is a break in the circuit between the control module and one of the wheel sensors. If the circuit is OK, the reading should be approximately 3.4 V.

Scheme 65

ABS warning lamp on. ABS not functioning.

1. Rear right wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Rear Right".

The current wheel speed in km/h is displayed.

1. With the rear wheels of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the RR wheel is rotated by hand at a speed of about 1 turn a second.

Scheme 66

ABS warning lamp on. ABS not functioning.

1. Rear right wheel speed sensor can be read using the diagnostic tool.

1. Select "Read values".
2. Select "Wheel Speed Rear Right".

The current wheel speed in km/h is displayed.

With the rear wheels of the car raised off the ground, the diagnostic tool should show a reading of about 5 km/h when the RR wheel is rotated by hand at a speed of about 1 turn a second.

1. For tracing electrical faults, the diagnostic tool can be used to take readings from the control module's wheel-sensor inputs.

1. Select "Read values"
2. Select "Wheel-sensor output"

The reading is used to determine whether there is a break in the circuit between the control module and one of the wheel sensors. If the circuit is OK, the reading should be approximately 3.4 V.

Scheme 67

ABS warning lamp on. ABS not functioning.

1. The respective wheel speed sensor signal can be read using the diagnostic tool.

1. Select "Read values".
2. Select: "Wheel speed".

The current wheel speed in km/h is displayed.

Scheme 68

ABS warning lamp on. ABS not functioning.

ABS warning lamp on. ABS not functioning.

The solenoid valves can be activated using the diagnostic tool.

1. Select "Activate".
2. Select "Valves"

Select the valve from the sub menu. The selected valve will be activated at a frequency of 1 Hz for about 30 s.

Scheme 69

ABS warning lamp on. ABS not functioning.

ABS warning lamp on. ABS not functioning.

The solenoid valves can be activated using the diagnostic tool.

1. Select "Activate".
2. Select "Valves"

Select the valve from the sub menu. The selected valve will be activated at a frequency of 1 Hz for about 30 s.

Change the control module. Refer to BEFORE CHANGING A CONTROL MODULE .

Scheme 70

ABS warning lamp on. ABS not functioning.

The pump motor can be activated using the diagnostic tool.

1. Select "Activate".
2. Select "Pump motor".
3. If the ABS control module is not grounding (pin 16), DTC C2465 will be generated.

Scheme 71

No fault symptoms.

The diagnostic tool can be used to determine the status of the brake-light switch (Open/Closed).

1. Select "Read values".
2. Select "Brake-light switch".

Scheme 72

1. The customer's description of the problem constitutes a basis for the fault diagnosis strategy. If necessary, the customer must demonstrate the trouble on the car to avoid misunderstandings.
2. In certain cases, the function may be correct. 2.a. Good product knowledge is required to decide this. 2.b. If the function is correct, this must be explained to the customer.
3. If the function is judged to be faulty, the car should be repaired. Saab's fault diagnosis strategy assumes that the technician is familiar with the customer's description of the problem. So note the customer's complaint and any other observations on the job sheet.
4. The technician obtains a readout of the diagnostic trouble codes from all systems. A malfunction in one system can often be caused by a fault in another system.
5. The car may contain diagnostic trouble codes which are secondary faults or which have been incorrectly generated. 5.a. Compare the customer's complaint with the symptom descriptions for the various diagnostic trouble codes. EPSI has a fast search path for this. 5.b. If the symptom description for a diagnostic trouble code matches the customer's complaint, this diagnostic trouble code is probably caused by the primary fault. Repair as per instructions.
6. If there is no match with diagnostic trouble codes or symptoms, the technician must diagnose the fault himself. 6.a. In EPSI, search under fault diagnosis on the basis of symptoms in the system where the fault has occurred. 6.b. If the symptom description in the current system matches the complaint, the right fault diagnosis description has probably been found. Repair as per instructions.
7. Certain fault symptoms can be remedied by reprogramming the control module. 7.a. Does the customer complaint stem from a known software problem in a programmable control module? 7.b. Reprogram the control module following the instructions in SPS.
8. If there is no match with diagnostic trouble codes or symptoms, the technician must diagnose the fault himself. A final check must be carried out after the repair. Good technical product knowledge is required to solve this type of problem.
9. The car is ready.

No diagnostic link

See " BUS AND DIAGNOSTICS COMMUNICATION " .

Scheme 73

Fault symptom

No diagnostics communication with ABS or TC/ABS

First check the fuses for the ABS or TC/ABS and that the pin in data link connector for the ABS or TC/ABS has not been dislodged.

Even thought the TC/ABS is connected to the P-bus, diagnostics communication is via the K line.

Then check whether the ABS or TC/ABS is awake and allows diagnostics communication. If this is the case, check whether the diagnostics tool works in another car.

If no fault is found, rectify the communication cables between the ABS or TC/ABS and the diagnostic data link.

Checking the wiring harness .

Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Scheme 74

The ABS warning light does not come on. (The ABS warning-light test is activated when the ignition is switched on. During this test, the light should come on for about three seconds.)

The ABS warning light can be activated using the diagnostic tool.

1. Select: "Activate".
2. Select: "ABS warning light".

ABS lamp shines constantly.

No DTCs generated.

The ABS warning lamp can be activated using the diagnostic tool.

1. Select "Activate".
2. Select "ABS warning lamp".

Scheme 75

Speedometer or cruise-control system not working.

The wheel-speed reading can be obtained from both the ABS control module and the control module receiving the signal.

See DIAGNOSIS in " FAULT DIAGNOSIS, SYMPTOMS ", or SELF-DIAGNOSTICS .

Scheme 76

TOOLS COMPATIBILITY - TECH 2

Scheme 77

Group: Test equipment

TOOLS COMPATIBILITY - MEASUREMENT CABLE, MALE PIN (X 4)

Scheme 78

Diagnostics

The control module monitors its own internal functions and the other ABS-system components.

If an internal fault occurs in the control module, diagnostic trouble code C1605 will be generated, the ABS warning light will come on and the ABS system will be disabled.

If the supply drops below 9 V for at least 0.5 s, diagnostic trouble code C1532 will be generated, the ABS warning lamp will come on and the ABS system will be disabled.

If there is a break in the circuit to pin 19, the ABS warning lamp will come on and the ABS system will be disabled. It will not be possible for a test instrument to communicate with the control module.

If there is a break in the circuit to pin 16, DTC C2465 will be generated, the ABS warning lamp will come on and the ABS system will be disabled.

Front-Wheel Sensors

The front left wheel sensor sends a wheel-speed signal to pin 7 on the control module. The sensor is grounded via pin 6.

The front right wheel sensor sends a wheel-speed signal to pin 5 on the control module. The sensor is grounded via pin 3.

The sensor unit has a toothed wheel with 29 teeth and an inductive sensor.

The inductive sensor works like a small alternator, the sine-wave voltage of which increases with increasing wheel speed. The sine-wave voltage alternates between positive and negative polarity, which is achieved by alternate teeth and gaps on the toothed wheel. The control module uses this change of polarity as a pulse sensor. The frequency of the pulses increases with the speed of the wheel.

With a multimeter set for AC voltage connected between the two leads of the sensor, a reading of 100 mVAC should be obtained when the wheel is rotated one revolution per second.

A wheel speed of 20 km/h gives about 5 VAC.

Scheme 79

Scheme 80

The distance between the sensor and the toothed wheel should be 0.3-1.2 mm. This distance is adjustable .

The control module uses the frequency to measure the vehicle speed .

If there is a break in the front left circuit, diagnostic trouble code C1372 is set, the ABS function is disabled and the ABS warning lamp lights up.

In the event of a mechanical fault or malfunction in the front left circuit, diagnostic trouble code C1371 is set, the ABS function is disabled and the ABS warning lamp lights up.

If there is a break in the front right circuit, diagnostic trouble code C1377 is set, the ABS function is disabled and the ABS warning lamp lights up.

In the event of a mechanical fault or malfunction in the front right circuit, diagnostic trouble code C1376 is set, the ABS function is disabled and the ABS warning lamp lights up.

Rear-Wheel Sensors

The rear left wheel sensor sends a wheel speed signal to pin 9 on the control module. The sensor is grounded via pin 8.

The rear right wheel sensor sends a wheel speed signal to pin 2 on the control module. The sensor is grounded via pin 1.

The wheel sensors are integrated into the wheel hubs and consist of an inductive sensor with 29 teeth.

The inductive sensor works like a small alternator, the sine-wave voltage of which increases with increasing wheel speed. The sine-wave voltage alternates between positive and negative polarity, which is achieved by alternate teeth and gaps on the toothed wheel.

The design of the rear-wheel sensor is different to that of the front-wheel sensor, and the sensor is less sensitive to play in the wheel bearings. With a multimeter set for AC voltage connected between the two leads of the sensor, a reading of 100 mVAC should be obtained when the wheel is rotated one revolution per second.

A wheel speed of 20 km/h gives about 5 VAC.

The control module uses the frequency to measure the vehicle speed.

Scheme 81

Scheme 82

If there is a break in the rear left circuit, diagnostic trouble code C1382 is set, the ABS function is disabled and the ABS warning lamp lights up.

In the event of a mechanical fault or malfunction in the rear left circuit, diagnostic trouble code C1381 is set, the ABS function is disabled and the ABS warning lamp lights up.

If there is a break in the rear right circuit, diagnostic trouble code C1387 is set, the ABS function is disabled and the ABS warning lamp lights up.

In the event of a mechanical fault or malfunction in the rear right circuit, diagnostic trouble code C1386 is set, the ABS function is disabled and the ABS warning lamp lights up.

Scheme 83

Several other systems in the car need to receive wheel-speed data. Because the ABS control module is not connected to a bus, it has a wheel-speed output for each wheel (only the rear left and right front are connected at present). A transistor in the ABS control module grounds the respective outputs 29 times per wheel revolution. The voltage across the output is monitored by the systems receiving the data.

The main instrument unit (MIU) receives the wheel-speed signal via a lead connected to the rear left wheel. The reason that a rear-wheel sensor has been chosen is that the distance travelled (recorded mileage) can be measured more accurately on a non-driving wheel. The MIU converts the frequency-modulated signal to km/h, a computation that includes a preprogrammed correction for tyre size.

Because the MIU is connected to a bus, all the other control modules connected to the bus are able to share the RL wheelspeed and milometer (odometer) data.

The Trionic system is connected to the ABS control module via pin 26, and it receives wheel-speed data from the front right wheel.

For more information on wheel-speed data from the bus, see BUS AND DIAGNOSTICS COMMUNICATION and " FAULT DIAGNOSIS, SYMPTOMS ".

If voltmeter measurements are made at any of the relevant terminal pins, the reading should alternate between 0 V and B+ voltage when the respective wheel is rotated slowly. Provided that the RL and FR wheel sensors are functioning, the wheelspeed signal is sent even if the ABS system is inoperative and the ABS warning light is on.

Scheme 84

Scheme 85

If the wheel-speed signal output is faulty, a DTC will be generated in the receiving system.

Brake-Light Switch

When the brake pedal is depressed, current is fed via the brake-light switch to pin 14 on the control module.

Information on the status of the brake-light switch (ON/OFF) is used by the electronic brake-force distribution function (EBD) during pump-motor testing and ABS modulation.

Each time the brake pedal is depressed, i.e. the control module receives current from the brake-light switch, ABS control reverts to the default mode.

Scheme 86

Scheme 87

The control module monitors the circuit by feeding a low current to pin 14, which is grounded via the brake-light lamps. If a break occurs in the circuit, DTC C2470 will be generated.

Scheme 88

The return pump, which is integrated into the hydraulic unit, consists of a D.C. motor that actuates a hydraulic pump.

The pump unit, which is only activated when an outlet valve is open, returns surplus brake fluid to the master cylinder.

The pressure in the return-fluid line is determined by the brake pressure in the master cylinder, which, in turn, is proportional to the pedal pressure.

The pump's capacity of approximately 250 bar is sufficient for all occurring braking conditions.

Each time the ignition is switched on and the road speed exceeds 6 km/h, the control module checks the operation of the return pump, activating it for 200 ms. If the brake-light switch is closed, the test will be done at a speed of 15 km/h.

The hydraulic pump and electric motor are an integral part of the valve block and cannot be replaced separately.

If a fault occurs in the pump motor or circuitry, a DTC C2465 will be generated, the ABS warning lamp will come on and the ABS system will be disabled.

Scheme 89

1. To master cylinder
2. To wheel cylinder
3. Inlet valve
4. Outlet valve
5. Pump
6. Accumulator chamber
7. Pressure chamber

The valve block, which is an integral part of the hydraulic unit, controls the brake pressure to the caliper assemblies during ABS-controlled braking.

The valve block includes eight solenoid valves: four inlet and four outlet (i.e. one pair per wheel).

In the rest position, the inlet valve is open and the outlet valve closed.

The valve block incorporates an accumulator chamber and a pressure chamber for each brake circuit. The accumulator chamber, which is located between the outlet and the return pump, accumulates the brake fluid until the return pump starts running.

The function of the pressure chamber, which is located between the return pump and master cylinder, is to dampen both noise and pressure fluctuations when the return pump is operating (ABS mode).

The control module performs a valve test each time the ignition is switched on. This test takes place at the same time as the pump-motor test and the valves are actuated for 20 ms.

A fault in a front left solenoid valve will generate DTC C2450.

A fault in a front right solenoid valve will generate DTC C2455.

A fault in a rear left solenoid valve will generate DTC C2415.

A fault in a rear right solenoid valve will generate DTC C2485.

In all the above cases, the ABS system will be disabled and the ABS warning light will come on.