Questions and Answers

Ford Aerostar Air Bag Code 52 Q. Hello Mr Vincent Ciulla, I have a 1993 Ford Aerostar, 4.0 liter engine with driver side airbag. The yellow warning light is currently blinking a 5-2 Code. I have asked my local Ford Dealer what this Code signifies and they say that they will have to do a complete diagnoses in order to tell me what is wrong.

It seems to me that if there is a computer control system involved, that the Code would signal that some portion of the total wiring and control systems is at fault. Therefore they should be able to suggest at least what the possible problem is and where it is located. Please advise your opinion on this and on the possible time required to repair.

Charles

A. Here is the information you will need to check the code 52. You need to be very, very careful when working with the SRS system.

GENERAL SAFETY PRECAUTIONS:
Always wear safety glasses when servicing an airbag vehicle and when handling an airbag module.

Because of the critical operating requirements of the system, do not attempt to repair sensor assemblies, the slip ring/clockspring assembly, the monitor assembly or the airbag module. Corrections are made by replacement only.

Never probe the connectors on the airbag module. Doing so may result in airbag deployment which could result in personal injury.

All component replacements and wiring repairs must be made with the airbag system disarmed. See Airbag System Disarming and Arming.

The instruction DISCONNECT always refers to a connector. Never detach a part from vehicle when instructed to Disconnect. If a vehicle equipped with an airbag system is involved in a crash where the fenders or grille area have been damaged, the sensors in the area of damage must be replaced whether or not the airbag deployed.

HANDLING & STORAGE OF LIVE AIRBAG MODULE:
When carrying a live airbag module, ensure bag and trim cover are pointed away from body. In the unlikely event of an accidental deployment, the bag will then deploy with minimal chance of injury. In addition, when placing a live airbag module on a bench or other surface, always place bag and trim cover face up, away from the surface. This will reduce the motion of the module if it is accidentally deployed.

HANDLING OF DEPLOYED AIRBAG MODULE:
After deployment, the airbag surface may contain deposits of sodium hydroxide, a product of the gas generant combustion that is irritating to the skin. Always wear gloves and safety glasses when handling a deployed airbag module.

Fault Code 52 - Backup Power Supply Voltage Boost Fault.

Normal Operation:

A backup power supply is contained within the diagnostic monitor that consists of four 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 backup 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 backup 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 code 52 to indicate low voltage in the backup power supply voltage boost circuit.

Possible Causes:

Low backup 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 backup 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 faulty it will not be able to raise the backup power supply voltage on the capacitor.