Abs Control Module Can Bus, Checking
Observe all safety precautions: SAFETY PRECAUTIONS
View clean working conditions: CLEAN WORKING CONDITIONS
Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
Special tools and workshop equipment required
- Multimeter
- Wiring diagram
Test requirement
- A CAN bus malfunction was recognized
- The module that does not communicate has ALL power and grounds present at the module connector. Refer to the Wiring Diagrams for pin locations.
- Battery voltage at least 12.5 volts
- All electrical consumers switched off
- Vehicles with automatic transmission, shift selector lever in park or neutral
- A/C switched off
- Ground connections between engine/transmission/chassis OK
- Ignition switched Off
Terminal Resistance checking
The Engine Control Module must remain connected for the following step.
-- Disconnect the Antilock Brake System (ABS) Module -J104- T38 electrical connector.
-- Using a multimeter, measure the resistance between the CAN bus low and CAN bus high terminals at the Antilock Brake System (ABS) Module -J104- harness connector (with ALL other modules connected). Refer to Wiring Diagrams for Pin locations.
| Antilock Brake System (ABS) Module -J104- electrical harness T38 connector terminals | CAN Bus I.D. |
|---|---|
| 24 | CAN Low |
| 22 | CAN High |
Specified value: 50 to 69 Ω (at approx. 20° C)
If the specified value was OK and the ABS is Not communicating:
-- Check the power and ground supply to the ABS module BEFORE replacing a module. Refer to Wiring Diagrams for power and ground inputs. Loss of a power or ground will cause a no response condition from the ABS module. If power and grounds are present at the ABS module, replace the Antilock Brake System (ABS) Module -J104-. Refer to the service information for removal and installation procedures.
If the specified value was Not OK :
Checking wiring
-- Remove the Engine Control Module (ECM) -J623- and disconnect the T94 electrical connector. Refer to the service information for removal and installation procedures.
-- Using a multimeter, measure the resistance of the CAN bus low circuit, then the CAN bus high circuit, between the ECM electrical connector and the ABS electrical connector. Refer to Wiring Diagrams for location.
| Antilock Brake System (ABS) Module -J104- electrical harness T38 connector terminals: | Engine Control Module (ECM)J623 electrical harness connector T94 terminals: |
|---|---|
| 24 | 67 |
| 22 | 68 |
Specified value: 1.5 Ω Max.
If the specification was Not obtained:
-- Check the wires for a short circuit to each other, a short to battery voltage, and a short to ground.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-- Repair as necessary.
If the Terminal Resistance was Not OK and no malfunction was found in the wiring:
-- Replace the Engine Control Module (ECM) -J623-. Refer to the service information for removal and installation procedures.
Final procedures
After repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .