CAN-Bus wiring, checking

Fig 1: Releasing ABS Control Module Connector

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Release ABS Control Module connector and remove.
• Release Engine Control Module (ECM) J248 connector and remove.
• Check CAN-Bus wiring for short to one another:
• Measure resistance between test box sockets 3 + 25, (test box 1598/18):

Specification: ∞ Ω

If specification is not obtained wiring is shorted:

• Repair wiring damage using wiring diagram: → Electrical Wiring Diagrams, Troubleshooting and Component Locations
• Check DTC memory, if necessary, repair any malfunctions and erase DTC memory → Diagnostic Trouble Code (DTC) memory, checking and erasing  .
• Display readiness code → Readiness code, displaying  . If DTC memory has been erased, reset readiness code → Readiness code, setting  .

If specification is obtained wires are not shorted:

Fig 2: Identifying Test Box V.A.G 1598/22 Connected To Control Module Wiring Harness

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Connect test box V.A.G 1598/22 (through my 1999) or test box V.A.G 1598/31 (from my 2000) to Engine Control Module (ECM) J248 wiring harness.
• Check CAN-Bus wiring between test box sockets for open circuit using wiring diagram:

• 1598/22 - 1598/18
• Socket 68 and - socket 3
• Socket 75 and - socket 25
• Wire resistance: max. 1.5 Ω

• Also, check wiring for short to battery positive (B+) or ground.

If no wiring damage is found:

Fig 3: Connecting Test Box V.A.G 1598/21 To ABS Control Module

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Connect test box V.A.G 1598/21 - 1  - to ABS Control Module - 2  - wiring harness.
• Check CAN-Bus wiring between the test box sockets for open circuit using wiring diagram:

• 1598/22 - 1598/21
• Socket 68 and - socket 10
• Socket 75 and - socket 11
• Wire resistance: max. 1.5 Ω