C1236

CIRCUIT DESCRIPTION
Diagnostic Trouble Code (DTC) C1236 monitors the voltage level available to the Electronic Brake Control Module (EBCM) controller. If the voltage drops below 11.2 volts, full performance of the ABS system is not guaranteed. During ABS operation, there are several current requirements that will cause battery voltage at the EBCM to drop. As a result, voltage is monitored prior to an ABS event to indicate good charging system condition. Voltage is also monitored during an ABS event when voltage may drop significantly.

CONDITIONS FOR SETTING THE DTC
^ Diagnostic Trouble Code (DTC) C1236 can set only if the vehicle's speed is greater than 5 km/h (3 mph).
^ A malfunction exists if both the switched battery and switched ignition voltages are less than 11 volts during non-ABS event, or less than 9 volts during an ABS event.

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction Diagnostic Trouble Code (DTC) stores.
^ The ABS disables.
^ The ABS warning indicator turns ON.

CONDITIONS FOR CLEARING THE DTC
^ The condition responsible for setting the Diagnostic Trouble Code (DTC) no longer exists and the Scan Tool Clear DTCs, function is used.
^ 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

DIAGNOSTIC AIDS
The following conditions may cause a malfunction:
^ A poor connection
^ Rubbed-through wire insulation
^ A broken wire inside the insulation
^ Vehicle's charging system is not operating properly (low generator output, faulty battery)
^ High resistance in the switched ignition or switched battery circuits
^ Poor G102

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.
Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:
^ Backed out terminals
^ Improper mating
^ Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal-to-wiring connections
^ Physical damage to the wiring harness

While performing a Voltage Load test, the switched ignition circuit should be measured for high resistance or an open condition if it is noted that only the ignition voltage drops below acceptable voltage levels.

Ensure the starting and charging systems are in proper working order. The battery should be fully charged and in good condition before beginning the diagnostic table.

TEST DESCRIPTION
3. This test checks for excessive resistance in the switched battery input circuit.
4. This test checks for excessive resistance in the battery feed circuit.
5. This test checks for an open or high resistance in the switched ignition circuit.
8. This test determines if the malfunction is caused by the EBCM.

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Part 2 Of 2:

DTC C1236 LOW SYSTEM SUPPLY VOLTAGE