C1254

C1236/C1254: Low System Voltage/Abnormal Shutdown Detected

CIRCUIT DESCRIPTION
This circuit is used to monitor voltage level available to 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 good charging system condition and also during ABS operation when voltage may drop significantly.

CONDITIONS FOR SETTING THE DTC
^ DTC C1236 can only be set if vehicles speed is greater than 8 kph (5 mph), if ignition voltage to terminal E136-15 and battery voltage to terminal E136-1 and E136-2 are less than 10.5 volts during non ABS or initialization. The DTC will also set if ignition voltage is below 10.5 volts and battery voltage is below 9.0 volts during ABS.
^ DTC C1254 will be set when EBCM has detected power or ground had been lost and then regained within short period of time.

ACTION TAKEN WHEN THE DTC SETS
^ ABS relay opens, removing voltage from solenoids and pump motor.
^ DTC (C1236 or C1254) is stored.
^ ABS disabled, ABS warning light turns on.

DIAGNOSTIC AIDS
Thoroughly inspect wiring and connectors. Failure to carefully and fully inspect wiring and connectors can cause replacement of parts without repairing the malfunction. Typical causes for DTC C1236 to set.
^ Weak or discharged battery.
^ Poor battery terminal contact.
^ Excessive battery draw from factory or aftermarket equipment (parasitic load).
^ Poor battery ground at block or chassis.
^ Poor terminal contact at EBCM.
^ Poor EBCM ground connection.
^ Charging system malfunction (generator).
Typical causes of DTC C1254.
^ Weak or Discharged battery.
^ Loose or poor battery terminals.
^ Battery disconnect.
^ Loose or poor ground cables.
^ Poor EBCM terminal contact.
^ Excessive parasitic draw.
^ Charging system malfunction.

INSPECTION

NOTE: Diagnostic flow table must be performed first before using this table.
Type 1