Diagnostic Trouble Code 52

Back Up Power Supply Voltage Boost Fault

Normal Operation

A back-up power supply is contained within the diagnostic monitor that consists of 4 capacitors and a voltage boost circuit. The voltage boost circuit charges the capacitors to 16-19 volts when the ignition switch is turned to ON. The back-up power supply is connected through a diode to diagnostic monitor Pin 15 (Circuit 611, W/O). The resistance of Circuit 611 to ground is infinite since it is an open circuit. This open circuit allows the capacitor to maintain its higher voltage because there is no discharge path for the capacitor. The diagnostic monitor measures the voltage on the back-up power supply capacitors. If the voltage on the capacitors does not reach and maintain a minimum of 16 volts after approximately 45 seconds, the diagnostic monitor will flash Diagnostic Trouble Code 52 to indicate low voltage in the back-up power supply voltage boost circuit.

Possible Causes

Low back-up power supply voltage can be caused by:

1. Resistance on Circuit 611 (W/O) to ground. Resistance to ground on Circuit 611 or Circuit 612 (P/O) will cause the back-up power supply capacitors to discharge and the boost circuit will not be able to boost the voltage.

2. Boost circuit failure within the diagnostic monitor. If the voltage boost circuit in the diagnostic monitor is damaged it will not be able to raise the back-up power supply voltage on the capacitor.

DIAGNOSTIC TROUBLE CODE 52

52-1 VERIFY CONDITION

• Turn key to ON.

• Count diagnostic trouble code.

• Wait 45 seconds.

• Is code 52 flashing?

GO to 52-2.

No
Read the normal operation description for this diagnostic trouble code. EXAMINE the diagnostic trouble code schematic and look for areas where intermittent conditions would occur (connectors, splices, crimps, etc.).
DO NOT proceed with Pinpoint Test until the code is flashing! Failure to do so will result in needless replacement of the air bag system components and repeat service.

 

52-2 CHECK DIAGNOSTIC MONITOR

• Deactivate system.

• Turn ignition switch from OFF to RUN.

• Wait 45 seconds.

• Measure voltage between Pin 15 (Circuit 611, W/O) and Pin 3 (Ground).

• Is voltage measured within 16-19 volts?

Yes
REPLACE diagnostic monitor. RECONNECT system. VERIFY system. REACTIVATE system.

No
GO to 52-3.

 

52-3 CHECK FOR OPEN IN CIRCUIT 611

• Turn ignition switch OFF.

• Disconnect diagnostic monitor.

• Set ohmmeter to 200 K scale or AUTO.

• Measure resistance of Pin 15 (Circuit 611, W/O) to Pin 3 (Ground).

• Is reading infinite (open)?
  
  
  
  
  

Yes
REPLACE diagnostic monitor. RECONNECT system. VERIFY system. REACTIVATE system.

No
GO to 52-4.

 

52-4 MEASURE RESISTANCE OF CIRCUIT 611

• Disconnect LH B-pillar safing sensor.

• Measure resistance between Pin 15 (Circuit 611, W/O) and Pin 3 (Ground).

• Is reading infinite (open)?

Yes
GO to 52-5.

No
LOCATE and SERVICE short to ground in Circuit 611, W/O. RECONNECT system. VERIFY system. REACTIVATE system.

 

52-5 CHECK FOR SHORT IN SENSOR

• Measure resistance of W/O wire in safing sensor connector to sheet metal ground.

• Is reading infinite (open)?
  
  
  
  
  

Yes
LOCATE and SERVICE short to ground in Circuit 612 (P/O). RECONNECT system. VERIFY system. REACTIVATE system.

No
REPLACE safing sensor. RECONNECT system. VERIFY system. REACTIVATE system.

---