1999-2009 [Subscribe to Daily Digest] |
Don't know if you still need this but:
The ABS 5.4 system in brief
The main advantages of the ABS system are:
No loss of directional stability on braking.
Steering control retained even during heavy braking.
Shortest possible braking distance.
Reduced tire wear
The Saab 9-5 is equipped with the ABS 5.4 system, which is a dual-circuit, four-port brake system containing the following principal components:
Wheel sensors (one on each wheel).
ABS hydraulic unit with the following integral components:
Valve block with one inlet and one outlet valve for each wheel
Return pump comprising electric motor and pump unit.
Control module with integral master and pump relay.
A wheel sensor on each wheel generates an alternating current, the frequency of which increases with increasing wheel speed. The ABS control module, which receives signals for wheel speed, continuously computes wheel acceleration, retardation, road speed and wheel slip (degree of lock-up). When a wheel comes close to the lock-up threshold, the control module activates the inlet/outlet valves and the return pump, thus modulating the brake pressure for the wheel in question, and enabling the maximum braking effect to be achieved without loss of steering control.
The control module incorporates a function known as Electronic Brake-Force Distribution (EBFD) , which controls the rear inlet valves such that the maximum braking effect is achieved on the rear wheels under different load conditions, without the risk of their locking up before the front wheels.
Several other systems in the car also need data on the vehicle's road speed. The MIU receives a signal, via a lead connected to the rear left wheel-speed sensor, which it then converts to km/h, a computation that includes a preprogrammed correction for tire 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 control module continuously monitors both its own internal functions and the functioning of the other system components. If a fault is detected, a Diagnostic Trouble Code (DTC) will be generated, the ABS warning lamp will come on and the ABS system will be disabled.
NOTE: The function of the ABS warning light is to be changed during the 1998 model year. After the new function has been introduced, when the ABS warning light comes on, this will also cause both the standard brake warning light and the central warning light come on. The circuitry between the ABS control module and the MIU will remain unchanged.
Note this is for a 99 9-5, ABS 5.4, might be slightly different for 2000.
posted by 4.156.117...
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