How to Extract Codes & Perform Tests

Fig. 3 Light pulse indications of trouble code identification.:

Start engine and warm to operating temperature. Turn engine off but leave key in the On position.
Connect male and female test leads taped into wiring harness near ECM. After leads are connected, the ``Check Engine'' lamp will flash appropriate trouble codes. The codes are indicated by a pulsing of the lamp. Two pulses followed by a short time lapse, then three pulses would indicate a code 23 and so on. If only one trouble code is stored, the code will repeat continuously until test leads are disconnected. If more than one trouble code is stored, each code will repeat three times, starting with the lowest, then proceed to the next code. After all codes have been shown, the pattern will repeat itself. Refer to Fig. 3, for light pulse indications and trouble code identification.
Trouble codes can be cleared by removing voltage to the ECM for 10 seconds. After a fault has been corrected, remove the ECM fuse or disconnect battery cables for 10 seconds.