C1236

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Circuit Description
This Diagnostic Trouble Code (DTC) is used to monitor the voltage level available to the Electronic Brake Control Module (EBCM). If the voltage drops below specific levels at specific times, full performance of the Antilock Brake System (ABS) system cannot be guaranteed. During an ABS event, there are several current requirements that will cause battery voltage to drop. Because of this, voltage is monitored prior to an ABS event and also during an ABS event operation when voltage may drop significantly.

Conditions for Setting the DTC
- DTC C1236 can set only if the vehicle's speed is greater than 5 km/in (3 mph).
- A malfunction exists if the switched battery voltage is less than 11.4 volts without ABS being active or less than 8.4 volts during an ABS event.

Action Taken When the DTC Sets
- A malfunction DTC stores.
- The ABS disables.
- The ABS warning indicator turns ON.

Conditions for Clearing the DTC
- The condition responsible for setting the 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 an intermittent malfunction:
- A poor connection
- Rubbed-through wire insulation
- A broken wire inside the insulation
- Vehicle charging system is not operating properly (low alternator output, faulty battery)
- High resistance in Circuit (CKT)s 1Y03, 9V01 and 9B01
- 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

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.

IMPORTANT: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.