Engine Self Test 1993-95 2.0L 4-Cylinder Engine

[1stgenWizard]

Overview;
1993 to 1995 Probes were equipped with an On Board Diagnostic (OBD) system to detect malfunctions in sensors and notified the driver through the Check Engine light on the instrument panel.

The 'Check Engine' light or MIL (Malfunction Indicator Light) light on the instrument cluster illuminates when the ignition is turned to the 'On' position. It will go off a second or two after the engine is started. If the light stays illuminated after the engine is started or illuminates while driving, there may be a problem with the engine. Checking for error codes is an easy way to find out what's wrong and what, if anything, caused the 'Check Engine' light to illuminate.


ProcedureThere are three ways to check for error codes:

Engine Code Scanner
If you have a Super STAR II or equivalent engine code scanner, you can perform a quick test on your engine to see if there's anything wrong. Simply connect it according to the manufacturer's instructions and write down the codes that appear. Codes are listed below.

Analog Voltmeter
If you don't have an engine code scanner, you can perform the same test with a standard analog voltmeter. Set the meter to read between 0 and 20 volts. Find the Data Link Connector under the hood, between the battery and the left fender. Connect the positive wire of the voltmeter to the Self-Test Output (STO) pin on the Data Link Connector (see image below). Connect the negative wire to a ground.

Key On Engine Off Self Test: Turn the ignition switch ON, but do not start the engine. When you're ready to start the test, connect a jumper between the Self-Test input (STI) pin and the Ground (GND) pin on the Data Link Connector (see image below).

Key On Engine Running Self Test: Start the engine and allow it to idle. When you're ready to start the test, connect a jumper between the Self-Test input (STI) pin and the Ground (GND) pin on the Data Link Connector (see image below).

The voltmeter will display a pulse for 3 seconds when the test is first started. Engine codes will appear on the display as a pulse. See below for how to interpret the pulses.

MIL Light
If you don't have an engine code scanner, the easiest way to check for error codes is by using the Malfunction Indicator light on the instrument cluster.

Key On Engine Off Self Test: Turn the ignition switch ON, but do not start the engine. When you're ready to start the test, connect a jumper between the Self-Test input (STI) pin and the Ground (GND) pin on the Data Link Connector (see image below).

Key On Engine Running Self Test: Start the engine and allow it to idle. When you're ready to start the test, connect a jumper between the Self-Test input (STI) pin and the Ground (GND) pin on the Data Link Connector (see image below).

The Malfunction Indicator light will go out after a second then will flash the engine error codes, if any. See below for how to interpret the flashes.

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Interpreting the CodesThe pulses on the voltmeter and the flashes on the Malfunction Indicator light translate into multi-digit codes. To simplify things, we'll call all flashes and pulses, pulses. There are two types of pulses. A long pulse is a pulse that lasts 1-1/2 seconds. A short pulse is a pulse that lasts a 1/2 second. These are pretty distinguishable. The long pulse represents the first digit, and the short pulse represents the second digit. So, if there are three long pulses followed by four short pulses, that would be the number 34. If there isn't any long pulse, the number is less than ten. Eight short pulses with no long pulse would be an 8 code. If there is a long pulse, but no short pulse, the code is 10. If there is more than one code, each code will be separated by a 4-second pause. When all the codes are displayed, the codes will repeat.

If there are no codes, then there are no problems found.

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Example; Codes 8 and 34

Clearing the CodesClear the PCM memory by disconnecting the negative battery cable then pressing on the brake pedal for at least 5 seconds.

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