DTC C1237 High System Supply Voltage. Buick Century 1998

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1998 🢒 Century 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1237 High System Supply Voltage

ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice
Power Distribution Schematics

Circuit Description

DTC C1237 detects high vehicle voltage levels prior to any required motor movement (initialization or ABS/ETS/TCS). If excessive voltage exists, demagnetization of the motor magnets may occur. Demagnetization of the motor magnets would eventually affect or eliminate ABS/TCS performance.

Conditions for Setting the DTC

DTC C1237 can set only if the vehicle's speed is greater than 5 km/h (3 mph).

A malfunction exists if the switched battery voltage is greater than 17.1 volts.

Action Taken When the DTC Sets

•	A malfunction DTC stores.

•	The ABS/ETS/TCS disables.

•	The amber ABS/ETS/TCS warning indicator(s) turn 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 DTC(s) detected.

Diagnostic Aids

The following conditions may cause an intermittent malfunction:

•	A generator failure

•	Rubbed-through wire insulation

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual for the procedure.

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

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

Step	Action	Value(s)	Yes	No
1	Was the Diagnostic System Check performed?	--	Go to Step 2	Go to Diagnostic System Check
2	Start the engine. Install a Scan Tool . Select Data List on the Scan Tool . Select Battery Voltage on the Scan Tool . Run the engine at approximately 2000 RPM and monitor the voltage. Is the voltage less than or equal to the specified voltage?	16 V	Go to Step 6	Go to Step 3
3	Turn the ignition switch to the OFF position. Disconnect the Electronic Brake Control Relay. Start the engine. Use the J 39200 in order to measure the voltage between the Electronic Brake Control Relay harness connector terminal C1 and ground. Run the engine at approximately 2000 RPM and monitor the voltage. Is the voltage less than or equal to the specified range?	16 V	Go to Step 4	Go to Charging System Check .
4	Turn the ignition switch to the OFF position. Reconnect the Electronic Brake Control Relay. Drive the vehicle at a speed above 5 km/h (3 mph). Use the Scan Tool in order to look for DTCs. Does DTC C1237 set as a current DTC?	--	Go to Step 5	Go to Step 6
5	Replace the EBCM/EBTCM. Is the repair complete?	--	Go to Diagnostic System Check	--
6	The malfunction is intermittent or is not present at this time. Is the repair complete?	--	Go to Diagnostic Aids	--