Test Cycle

An integrated test program runs off in the control unit when switching on ignition.

A further test program runs off at a road speed of 6 krn/h.

Testing at 6 km/h can be felt, since pump in hydraulic unit will run briefly.

Test cycle is repeated each time car moves off, if ignition had been turned off previously.

Testing includes; electronic control unit, hydraulic unit, speed sensors, relays and wire harness.

A shortcoming is shown by the ABS indicator lamp coming on. If the shortcoming is recognized,

ABS will be switched off. Operation of "conventional brake system" is guaranteed.

Wire Harness / Relays / Overvoltage Cutout

ABS has its own wire harness (No. 121}.

1 — Hydraulic unit plug

2 — Hydraulic unit ground

4 - Front speed sensors

7 — Central informer connection

8 — Steering mount ground

9 - Plug next to CEB

10 — Rear speed sensors

Power supply for the electronic control unit and pump motor relay comes via relay no. XVII on central electric board (arrow).

An overvoltage cutout is integrated in this relay and protects the electronic control unit against excessive voilage.

Porsche 928 Ceb

Wire harness has a 35-pin plug for connection on the electronic control unit

Relay (1) for solenoid valves and relay (2) for pump motor as well gs a 12-pin wire plug (3) are located under cover oi hydraulic unit. The plug socket has a diode for activation of ABS indicator lamp when multiple pin plug on electronic control unit is disconnected.

1 — Relay for solenoids

Connecting terminal for power supply (battery +) is located In engine compartment on bracket for hydraulic unit.

Wire (6) leads into the 12-pin plug.

4 - Connecting terminal

5 — Protective cap

Ground wire (9) for hydraulic unit is connected on wheel house wall

7 — Relay for solenoids

Speed sensor wires are connected on ABS wire harnesses with wire plugs

Wires have a gas-proof cover Precisely positioned rubber mounts and grommets are connected permanently on wire cover for routing of wires

Wires on rear wheel sensors are surrounded by an additional protective sleeve between the mounting points.

tStO
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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