Circuit Description
This circuit is used to monitor the voltage level available to the electronic brake control module (EBCM). If the voltage drops below a certain level, full performance of the system cannot be guaranteed. During ABS operation, there are several current requirements that will cause battery voltage to drop. Because of this, voltage is monitored prior to ABS operation to indicate a good charging system condition and also during ABS operation when voltage may drop significantly.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1102 Battery Voltage Low
Conditions for Running the DTC
Vehicle speed is greater than 8 km/h (5 mph).
Conditions for Setting the DTC
Ignition voltage to terminal 4 and battery voltage to terminal 9 and 25 are less than 10.5 volts during non ABS or initialization. The DTC will also set if the ignition voltage is below 10.5 volts and the battery voltage is below 9 volts during ABS.
Action Taken When the DTC Sets
| • | The solenoid relay opens, removing voltage from the solenoids and pump motor. |
| • | DTC C1102 is stored. |
| • | ABS disabled, ABS warning lamp turns ON. |
Conditions for Clearing the DTC
| • | If the conditions that set the DTC C1102 are no longer present, the DTC may be cleared by using the proper scan tool. |
| • | The DTC that has not occurred in 100 drive cycles will be cleared from history data. |
Diagnostic Aids
Typical causes for DTC C1102 to set:
| • | Weak or discharged battery |
| • | Poor battery terminal contact |
| • | Excessive battery draws from factory or after-market equipment parasitic load. |
| • | Poor battery ground at block or chassis |
| • | Poor terminal contact at the EBCM |
| • | Poor EBCM ground connection |
| • | Charging system malfunction generator |
Thoroughly inspect the wiring and the connectors. Failure to inspect the wiring and the connectors carefully and fully can cause replacement of parts without repairing the malfunction.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Were the voltages within the specified range? | 9.4-17 V | Go to Step 3 | Go to Step 4 |
3 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
4 | Check the battery voltage between the terminal (+) and terminal (-) of the battery. Was the voltage within the specified range? | 9.4-17 V | Go to Step 6 | Go to Step 5 |
5 | Replace the battery. Did you complete the replacement? | -- | Go to Step 12 | -- |
6 | Check the resistance between terminal 4 of the EBCM connector and the terminal (+) of the battery. Does the resistance measure less than the specified value? | 1 ohms | Go to Step 8 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 12 | -- |
8 | Check the resistance between terminal 8, 24 and G102. Does the resistance measure less than the specified value? | 1 ohms | Go to Step 10 | Go to Step 9 |
9 | Repair or replace the EBCM connector or G102. Did you complete the repair? | -- | Go to Step 12 | -- |
10 |
Do the voltages measure less than the specified value? | 17 V | Go to Step 12 | Go to Step 11 |
11 | Repair the alternator. Did you complete the repair? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | Go to Step 2 | System OK | |
