Circuit Description
The instrument cluster controls the operation of the ABS indicator. The EBCM/EBTCM reports the desired status of the ABS indicator via class 2 serial data messages. The ABS indicator signal circuit is a back-up reporting circuit to the class 2 serial data messages. The EBCM/EBTCM supplies ground through the circuit when the ABS is operating properly. When there is a problem with ABS that should turn on the ABS indicator, the EBCM/EBTCM opens the ABS indicator signal circuit. If there is a problem with the ABS class 2 serial data messages, the instrument cluster uses the ABS indicator signal to determine if the ABS indicator should be illuminated. Using the serial data messages and back-up circuit, the instrument cluster decides whether to turn on the ABS indicator.
Conditions for Setting the DTC
The EBCM/EBTCM commands the ABS indicator ON when one of the following conditions are detected:
| • | An open |
| • | A short to ground |
| • | A short to voltage |
Action Taken When the DTC Sets
| • | A malfunction DTC is stored. |
| • | The ABS is not disabled. |
| • | The ABS indicator remains OFF. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and you used the scan tool Clear DTC function. |
| • | The EBCM/EBTCM does not detect the DTC in 50 drive cycles. |
Diagnostic Aids
| • | It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction. |
| • | An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation. |
| • | If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests if the instrument cluster can operate the ANTILOCK indicator.
-
This step tests for a short to ground in CKT 852.
-
This step tests for a short to voltage in CKT 852.
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This step tests for an open in CKT 852.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the ABS Diagnostic System Check performed? | -- | Go to Step 2 | |
2 |
Is DTC U1300 or DTC U1301 set? | -- | Go to DTC U1300 Class 2 Short to Ground or DTC U1301 Class 2 Short to Battery in Data Link Communications | Go to Step 3 |
Does the ANTILOCK indicator turn ON then OFF? | -- | Go to Step 4 | Go to Step 10 | |
Is the resistance equal to the specified value? | OL (Infinite) | Go to Step 6 | Go to Step 5 | |
5 | Repair the short to ground in CKT 852. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
Is the voltage more than the specified value? | 1 V | Go to Step 8 | Go to Step 7 | |
Is the resistance less than the specified value? | 5 ohms | Go to Step 11 | Go to Step 9 | |
8 | Repair the short to voltage in CKT 852. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
9 | Repair the open in CKT 852. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | -- | |
10 | Suspect the instrument cluster. Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console. Is the diagnosis complete? | -- | -- | |
11 | Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | -- |
