Circuit Description
The pump motor is an integral part of the Brake Pressure Modulator Valve (BPMV). The electronic brake control relay supplies power to the solenoid valves and pump motor. The electronic brake control relay, located in the EBCM/EBTCM, is activated whenever the ignition switch is in the RUN position and no faults are present. The electronic brake control relay remains engaged until the ignition switch is turned off or a failure is detected.
Conditions for Setting the DTC
DTC C1242 will set anytime the system voltage is greater than 8 volts and the pump motor is commanded off. A DTC exists if the voltage across the pump motor is between 3.3 and 5.2 volts for 2.0 seconds.
Action Taken When the DTC Sets
| • | A malfunction DTC is stored. |
| • | ABS/TCS is disabled. |
| • | ABS/TCS indicators are turned on. |
Conditions for Clearing the DTC
| • | Condition for DTC is no longer present and scan tool clear DTC function is used. |
| • | 100 ignition cycles have passed with no DTCs detected. |
Diagnostic Aids
| • | Possible causes for DTC C1242 to set are: |
| - | The pump motor internals has a open. |
| - | The pump motor circuit is open. |
| • | The pump motor is part of Brake Pressure Modulator Valve (BPMV) and is not serviceable separately. |
| • | The solenoid valve control relay is integral to the EBCM/EBTCM and is not serviceable separately. |
| • | 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. |
| • | If an intermittent malfunction exists refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Test Description
The numbers below refer to step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | ||
Is the resistance within the range specified in the value(s) column? | 0-2 ohms | |||
3 | Repair open or high resistance in CKT 251B. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
4 |
Is connector OK and cavity free of brake fluid? | -- | ||
5 |
Is the replacement complete? | -- | -- | |
6 | Using the J 39200 DMM and J 35616 Connector Test Kit measure the resistance between pump motor terminals. Remember to zero DMM first before proceeding with this test. Is the resistance within the range specified in the Value(s) column? | Less than 2 ohms | ||
7 | Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module/Electronic Brake and Track Control Module Replacement . Is the replacement complete? | -- | -- | |
8 | Replace the BPMV. Refer to Brake Pressure Modulator Valve Replacement . Is the replacement complete? | -- | -- |
