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Abs Circuits

When checking circuits of ABS module, refer to ABS MODULE CONNECTOR CIRCUIT IDENTIFICATION  table.

ABS MODULE CONNECTOR CIRCUIT IDENTIFICATION

Terminal No. Related Circuit
1 Power Supply
2 ABS Hydraulic Unit; Return Flow Pump Relay
3 ABS Hydraulic Unit; Left Front TCS Switch
4 ABS Hydraulic Unit; Left Front TCS Outlet Valve
5 ABS Hydraulic Unit; Left Front ABS Inlet Valve
6 ABS Hydraulic Unit; Right Front ABS Inlet Valve
7 ABS Hydraulic Unit; ABS Return Flow Pump Relay
9 (1) Left Front ABS Wheel Speed Sensor
10 Left Front ABS Wheel Speed Sensor
11 Right Rear ABS Wheel Speed Sensor
12 Left Rear ABS Wheel Speed Sensor
13 Left Rear ABS Wheel Speed Sensor
14 Right Front ABS Wheel Speed Sensor
15 (1) Right Front ABS Wheel Speed Sensor
18 Engine Control Module; Engine Torque & Misfire Monitoring
19 ABS Hydraulic Unit; ABS Return Flow Pump Control
25 ABS Hydraulic Unit; Left Rear ABS Outlet Valve
26 ABS Hydraulic Unit; Right Front ABS Outlet Valve
27 ABS Hydraulic Unit; Right Front Traction Outlet Valve
28 Ground Terminal
29 Ground Terminal
32 Electrical Connection To Instrument Cluster
33 ABS Hydraulic Unit; Left Front ABS Outlet Valve
34 ABS Hydraulic Unit; Right Rear ABS Outlet Valve
35 (1) Left Front Wheel Speed Sensor
37 ABS Hydraulic Unit; Energize ABS Solenoid Valve Relay
38 Right Rear Wheel Speed Sensor
42 Right Front Wheel Speed Sensor
46 K-Wire
47 (2) Stoplight Switch
48 Stoplight Switch
50 Positive Battery Voltage
53 ABS Hydraulic Unit; Left Rear ABS Inlet Valve
54 ABS Hydraulic Unit; Right Front ABS Inlet Valve
55 ABS Hydraulic Unit; Right Front TCS Switch Over Valve
(1) Vehicles with front wheel drive and ABS/TCS.
(2) Vehicles with all-wheel drive and ABS/TCS.
Fig 1: Identifying Terminals Of ABS Control Module 88-Pin Connector
G97C07413Courtesy of AUDI OF AMERICA, INC.

  1. Left Front Inlet & Outlet Valves

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 5 and 33. Resistance should be 9-22 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  2. Right Front Inlet & Outlet Valves

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 26 and 54. Resistance should be 9-22 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  3. Left Rear Inlet & Outlet Valves

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 25 and 53. Resistance should be 9-22 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  4. Right Front Inlet & Outlet Valves

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 6 and 34. Resistance should be 9-22 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  5. Left Front TCS Switchover Valve

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 3 and 55. Resistance should be 12-28 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  6. Left Front & Right Front TCS Outlet Valves

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 4 and 27. Resistance should be 12-28 ohms. If resistance is not within specification, check inlet and outlet valve circuits in wiring harness between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace hydraulic unit.

  7. Left Front Wheel Speed Sensor

    - Measure resistance between specified Test Box (VAG 1598/20) terminals. See TEST TERMINAL IDENTIFICATION  table. Resistance should be 400-2300 ohms. If resistance is not within specification, check wheel speed sensor harness circuit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace suspect wheel speed sensor.
    TEST TERMINAL IDENTIFICATION

    Application Terminals No.
    Front Wheel Drive W/O TCS & EDL 10 & 36
    Front Wheel Drive With EDL 9 & 10
    Front Wheel Drive With EDL & TCS 9 & 10

  8. Right Front Wheel Speed Sensor

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 14 and 15 (14 and 42 on models with TCS). Resistance should be 400-2300 ohms. If resistance is not within specification, check wheel speed sensor harness circuit for open, short to ground and short to power. Also check harness connector at suspect wheel speed sensor. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace suspect wheel speed sensor.

  9. Left Rear Wheel Speed Sensor

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 12 and 13. Resistance should be 400-2300 ohms. If resistance is not within specification, check wheel speed sensor harness circuit for open, short to ground and short to power. Also check harness connector at suspect wheel speed sensor. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace suspect wheel speed sensor.

  10. Right Rear Wheel Speed Sensor

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 11 and 38. Resistance should be 400-2300 ohms. If resistance is not within specification, check wheel speed sensor harness circuit for open, short to ground and short to power. Also check harness connector at suspect wheel speed sensor. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace suspect wheel speed sensor.

  11. ABS Solenoid Valve Relay

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 2 and 37. Resistance should be 30-80 ohms. If resistance is not within specification, check relay circuits between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace ABS solenoid valve relay.

  12. ABS Return Flow Pump Relay

    - Measure resistance between Test Box (VAG 1598/20) terminals No. 2 and 7. Resistance should be 30-80 ohms. If resistance is not within specification, check relay circuits between ABS control module and hydraulic unit for open, short to ground and short to power. See WIRING DIAGRAMS  . Repair if necessary. If wiring is okay, replace ABS return flow pump relay.

  13. Left Front ABS Inlet Valve

    - Raise support vehicle. Turn ignition on. Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 26 and 37. Connect a third jumper wire between terminals No. 5 and 28. Have an assistant depress and hold brake pedal. Turn left front wheel by hand. If left front brake locks, attempt to turn another wheel. If another wheel can be turned, hydraulic brakelines are improperly routed. If all brakes lock, replace faulty left front inlet valve. Disconnect jumper wires. Left front brake should now lock.

  14. Right Front ABS Inlet Valve

    - Raise support vehicle. Turn ignition on. Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 28 and 37. Connect a third jumper wire between terminals No. 28 and 54. Have an assistant depress and hold brake pedal. Turn right front wheel by hand. If right front brake locks, attempt to turn another wheel. If another wheel can be turned, hydraulic brakelines are improperly routed. If all brakes lock, replace faulty right front inlet valve. Disconnect jumper wires. right front brake should now lock.

  15. Left Rear ABS Inlet Valve

    - Raise support vehicle. Turn ignition on. Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 28 and 37. Connect a third jumper wire between terminals No. 53 and 28. Have an assistant depress and hold brake pedal. Turn left rear wheel by hand. If left rear brake locks, attempt to turn another wheel. If another wheel can be turned, hydraulic brakelines are improperly routed. If all brakes lock, replace faulty left rear inlet valve. Disconnect jumper wires. Left rear brake should now lock.

  16. Right Rear ABS Inlet Valve

    - Raise support vehicle. Turn ignition on. Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 28 and 37. Connect a third jumper wire between terminals No. 6 and 28. Have an assistant depress and hold brake pedal. Turn right rear wheel by hand. If right rear brake locks, attempt to turn another wheel. If another wheel can be turned, hydraulic brakelines are improperly routed. If all brakes lock, replace faulty right rear inlet valve. Disconnect jumper wires. Right rear brake should now lock.
    NOTE: Steps 17) and 18) apply only to models equipped with Electronic Differential Lock (EDL).
  17. Return Flow Pump, Left Front TCS Switchover & Outlet Valves, Pressure Limiting Valve, Left Front ABS Outlet Valve & Right Rear ABS Outlet Valve Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 7 and 37. Connect a third jumper wire between terminals No. 28 and 37. Connect a brake pressure gauge to left front brake caliper. Bleed air from caliper. Connect a fourth jumper wire between terminals No. 3 and 28. Turn ignition on, then after not more than 10 seconds turn ignition off. When ignition is on, return flow pump should run. Pressure gauge should indicate a maximum pressure of 72.5 PSI. Connect another jumper wire between terminals No. 4 and 28. Turn ignition on, then after not more than 10 seconds, turn ignition off. When ignition is on, outlet valve should operate and gauge pressure should increase to 2100-2825 PSI. If pressure is not as specified, replace ABS hydraulic unit.
  18. Return Flow Pump, Right Front TCS Switchover & Outlet Valves, Pressure Limiting Valve, Right Front ABS Outlet Valve & Left Rear ABS Outlet Valve Connect a jumper wire between Test Box (VAG 1598/20) terminals No. 1 and 2. Connect another jumper wire between terminals No. 7 and 37. Connect a third jumper wire between terminals No. 28 and 37. Connect a brake pressure gauge to left front brake caliper. Bleed air from caliper. Connect a fourth jumper wire between terminals No. 28 and 55. Turn ignition on, then after not more than 10 seconds turn ignition off. When ignition is on, return flow pump should run. Pressure gauge should indicate a maximum pressure of 72.5 PSI. Connect another jumper wire between terminals No. 27 and 28. Turn ignition on, then after not more than 10 seconds, turn ignition off. When ignition is on, outlet valve should operate and gauge pressure should increase to 2100-2825 PSI. If pressure is not as specified, replace ABS hydraulic unit.
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