ABS Modulator

The ABS modulator controls the supply of hydraulic pressure to the brakes in response to inputs from the ABS ECU. The modulator is attached by three mounting bushes to a bracket on the LH inner wing, and connected to the primary and secondary hydraulic circuits downstream of the master cylinder assembly. Two electrical connectors link the ABS modulator to the vehicle wiring. Internal passages in the ABS modulator, separated into primary and secondary circuits, connect to the various components that control the supply of hydraulic pressure to the brakes. Valves and check valves control the flow through the internal circuits. A damper chamber and restrictor are included in each circuit to refine system operation. Inlet and outlet solenoid valves control the flow to the individual brakes. An expansion chamber is connected to each circuit to absorb pressure. A return pump is connected to both circuits to provide a pressure source.

Fig 1: ABS Modulator Location

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

ABS ECU HARNESS CONNECTOR C0506 PIN DETAILS

Pin No.	Description	Input/Output
1	Ground	-
2	Battery power supply	Input
3	Pre-charge pump power supply	Output
4	Pre-charge pump ground	-
5	Ground	-
6	Battery power supply	Input
7	HDC active signal	Output
8	DSC sensor lateral acceleration	Input
9	DSC sensor test	Output
10	DSC sensor rotation rate	Input
11	Diagnostic DS2 bus	Input/Output
12	Front LH wheel speed sensor signal	Input
13	Rear LH wheel speed sensor reference voltage	Output
14	Rear RH wheel speed sensor reference voltage	Output
15	Front RH wheel speed sensor reference voltage	Output
16	Front RH wheel speed sensor signal	Input
17	HDC switch	Input
18	Front RH wheel speed	Output
19	Rear RH wheel speed	Output
20	ABS indicator light	Output
21	DSC sensor ground	-
22	Not used	-
23	Power supply from ECM relay	Input
24	CAN bus high	Input/Output
25	Brake pressure sensor ground	-
26	Brake pressure sensor signal	Input
27	DSC switch	Input
28	Front LH wheel speed sensor reference voltage	Output
29	Rear LH wheel speed sensor signal	Input
30	Not used	-
31	Rear RH wheel speed sensor signal	Input
32	Brake switch	Input
33	Not used	-
34	Rear LH wheel speed	Output
35	Front LH wheel speed	Output
36	Brake fluid level switch	Input
37 and 38	Not used	-
39	DSC sensor power supply	Output
40	CAN bus low	Input/Output
41	DSC sensor rotation rate reference	Input
42	Brake pressure sensor reference voltage	Output