Performance Probe > Do It Yourself> Diagnostics> Engine Self Test 1991-92 3.0L V-6 Engine Engine Self Test: 1991-92 3.0L V-6 Engine [Print Page] Overview 1990 to 1992 Probes with 3.0L engines 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. There are two types of self tests. The first is the Key On Engine Off (KOEO) Self Test, which tests the memory and certain sensors for any fault codes. The second test is the Key On Engine Running (KOER) Self Test, which allows you to check for faults present only when the engine is running. Procedure There 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 15 volts. Find the OBD Self Test 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 OBD Connector (see image below). Connect the negative wire to a ground. Key On Engine Off Self Test: Start the engine and run intil it reaches the normal operating temperature. Turn the ignition switch OFF for 10 seconds, then turn the ignition switch ON, but do not start the engine. When you're ready to start the test, connect a jumper wire between the Self-Test Input (STI) connector and the Signal Return wire on the diagnostic test connector. The STI wire is a white wire with a red stripe located just behind and slightly to the right of the right strut mount. Key On Engine Running Self Test: Start the engine and run intil it reaches the normal operating temperature. Turn the ignition switch OFF for 10 seconds, then restart the engine and allow it to idle. When you're ready to start the test, connect a jumper wire between the Self-Test Input (STI) connector and the Signal Return wire on the diagnostic test connector. The STI wire is a white wire with a red stripe located just behind and slightly to the right of the right strut mount. 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: Start the engine and run intil it reaches the normal operating temperature. Turn the ignition switch OFF for 10 seconds, then turn the ignition switch ON, but do not start the engine. When you're ready to start the test, connect a jumper wire between the Self-Test Input (STI) connector and the Signal Return wire on the diagnostic test connector. The STI wire is a white wire with a red stripe located just behind and slightly to the right of the right strut mount. Key On Engine Running Self Test: Start the engine and run intil it reaches the normal operating temperature. Turn the ignition switch OFF for 10 seconds, then restart the engine and allow it to idle. When you're ready to start the test, connect a jumper wire between the Self-Test Input (STI) connector and the Signal Return wire on the diagnostic test connector. The STI wire is a white wire with a red stripe located just behind and slightly to the right of the right strut mount. 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. OBD-I Connector Interpreting the Codes The pulses on the voltmeter and the flashes on the MIL light translate into three 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 two digits of a three digit code. The short pulse represents the last digit. The number 327 would be 3 long pulses, a pause, 2 long pulses, a pause, 7 short pulses. If there is more than one code, each code will be separated by a 4-second pause. Continuous Memory Codes are codes that appear while normal running and are stored by the computer for a period of time. During the Key On Engine Off Self Test, after all the codes are displayed, there will be a six second pause, a single flash, followed by another six second pause. Any Continuous Memory Codes will then be displayed in the same fashion as the regular codes. Continuous Memory Codes will only display once, before being erased, so make sure you're ready for them. If there are no problems found, code 111 will be displayed. Codes 327 Engine Self Test: Codes   Code Key Sensor or System 111 System Pass 112 ACT sensor circuit grounded 113 ACT sensor circuit open 114 ACT sensor input is out of Self-Test range 116 ECT sensor input is out of Self-Test range 117 ECT sensor circuit grounded 118 ECT sensor circuit open 121 TP sensor input is out of Self-Test range 122 TP sensor input is less than Self-Test minimum voltage 123 TP sensor input is greater than Self-Test maximum voltage 126 MAP sensor input is out of Self-Test range 129 Insufficient MAP input change during Dynamic Response Test 144 No HEGO switching detected 167 Insufficient TP input change during Dynamic Response Test 171 Lack of HEGO switching, system at adaptive limits (Rear Side) 172 HEGO sensor circuit indicates system always lean (Rear Side) 173 HEGO sensor circuit indicates system always rich (Rear Side) 175 Lack of HEGO switching, system at adaptive limits (Front Side) 176 HEGO sensor circuit indicates system always lean (Front Side) 177 HEGO sensor circuit indicates system always rich (Front Side) 179 Fuel system at part throttle lean adaptive limit, system rich (Rear Side) 181 Fuel system at part throttle rich adaptive limit, system lean (Rear Side) 182 Fuel system at idle lean adaptive limit, system rich (Rear Side) 183 Fuel system at idle rich adaptive limit, system lean (Rear Side) 188 Fuel system at part throttle lean adaptive limit, system rich (Front Side) 189 Fuel system at part throttle rich adaptive limit, system lean (Front Side) 191 Fuel system at idle lean adaptive limit, system rich (Front Side) 192 Fuel system at idle rich adaptive limit, system lean (Front Side) 211 Profile Ignition Pickup (PIP) circuit failure 212 Loss of tachometer/IDM input to EEC processor 213 EEC processor spark output (SPOUT) circuit open 326 PFE sensor circuit voltage lower than expected 327 PFE sensor circuit voltage below Self-Test minimum 332 Insufficient EGR flow detected 335 PFE sensor voltage out of Self-Test range 336 PFE sensor circuit voltage higher than expected 337 PFE sensor voltage above Self-Test maximum 411 Cannot control RPM during KOER low RPM check 412 Cannot control RPM during KOER high RPM check 452 Insufficient input from the Vehicle Speed Sensor (VSS) 511 EEC processor Read Only Memory (ROM) test failure 512 EEC processor Keep Alive Memory (KAM) test failure 513 Failure in EEC processor internal voltage 519 Power Steering Pressure Switch (PSPS) circuit open 521 Power Steering Pressure Switch (PSPS) circuit did not change states 525 Vehicle was either in gear or AC was on during Self-Test 528 Clutch Engage Switch circuit failure 538 Insufficient RPM change during KOER Dynamic Response Test 542 Fuel pump circuit open - EEC processor to motor ground 543 Fuel pump circuit open - Battery to EEC processor 556 Fuel pump circuit failure 558 Electronic Vacuum Regulator (EVR) circuit failure 563 High Speed Electro-Drive Fan (HEDF) circuit failure 564 Electro-Drive Fan (EDF) circuit failure 565 Canister Purge circuit failure 998 Hard fault present (FMEM mode) Codes Not Listed Service codes displayed are not applicable to the vehicle being tested No Code Unable to initiate Self-Test or unable to output Self-Test codes Key: = Key On Engine Off = Key On Engine Running = Continuous Memory
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