How to Read Trouble Codes From Your 1993 to 1995 OBD-I Ford Probe

Here is a complete list of MECS-II engine trouble codes, taken from "How to Understand, Service and Modify Ford Fuel Injection & Electronic Ignition Control." I offer this as a FAQ for those with 1993-95 Probes.

Basically, you can use a wire or a large paper clip to connect the GND pin to the TEN pin on your diagnostic connection. The connection is located in the front driver side corner under the hood, between the fender and the battery.

After making the connection, turn the key to the ON position (turn the ignition on, but do not start the car). The check engine light will blink out the trouble codes. Below is an explanation of how the light shows the codes and some other notes.

Interpreting the check light:

LONG PULSE - (1.2 seconds) counts off the first digit (or tens position) in code
SHORT PULSE - (0.4 seconds) counts off the second digit (or ones position) in code

Long pulse and short pulse sections are separated by 1.6 second gap, individual pulses separated by a 0.4 second gap, and codes are separated by a 4 second gap.

OPTIONAL METHOD

TEST CONNECTOR:
Single pin (green casing) located driver's side under hood rearward of strut mount, to be grounded.

Larger, 6-pin (actually, only 3 pins used) green casing, same location, for code signals as per:

Casing:

1: Red/Black 12 V
2: Light Green/Black Code Pulse
3: White/Yellow Monitor Lamp

CAUTION:
The Red/Black wire is coming directly from the main relay, which in turn is supplied from the battery through a 30A fuse. Leave this connector alone.

OPERATION NOTE:
If you decide to hook up a light bulb between the connector and ground as a quick code reader, please note that ON means that the connector voltage drops to about 6.2 V, while OFF means that the voltage is at battery voltage... so it may be better to hook up a piezo-electric buzzer between pins 1 and 2 in the above diagram. Note also that the Monitor Lamp wire allows you to check the operation of all the various switches inside the car, like the clutch/neutral switch, the brake switch, the idle switch, AC switch, headlight switch, rear defroster switch, blower switch, inhibitor switch, thermostat switch (fan), daytime running light control unit.

TO CLEAR THE CODES:
Codes are stored in KAM, or "Keep Alive Memory" which is powered by the car battery. To clear the KAM, disconnect the battery for at least 5 minutes. A problem with this is that the PCM (Powertrain Control Module) will lose what it has "learned" and you may experience drivability problems for 10-15 miles, but no damage should occur.

To help alleviate some of these problems, after resetting your PCM, start the car and let it idle for approximately 10-15 minutes, so that the PCM re-learns the engine's idle characteristics.  Also, drive the car 'normally' for approximately 15-20 miles, so the PCM will re-learn your driving habits.

Once that is done, the car should be running just fine!

TABLE OF CODES