Without Scan Tool

CAUTION: In some cases proper diagnostics cannot be determined by only using fault codes. Remember that they are only the result, not necessarily the reason for the problem. This driveability test procedure is designed for use with the Diagnostic Readout Box not the flashing power loss lamp.

If suitable diagnostic read-out tool is not available, stored fault codes can be accessed directly through the power loss/check engine lamp. To call up codes, cycle ignition switch on, off, on, off and on within 5 seconds. Stored codes will be indicated by flashes of the power loss/check engine lamp. The codes will be indicated as two digit numbers, with a four second pause between codes. An example of a code is as follows:

1. Power Loss/Check Engine Lamp illuminated for approximately 2 to 3 seconds as a bulb check, then turns off.
2. Lamp flashes 2 times, pauses, then flashes 6 times.
3. Lamp pauses for approximately 4 seconds.
4. Lamp flashes 3 times, pauses, then flashes 1 time.
5. This would indicate that code 26 and 31 are stored. The lamp will continue to flash until all stored codes have been displayed.

Once the lamp starts flashing the stored fault codes, it cannot be stopped. If a code is missed, the entire procedure must be repeated. The lamp will not indicate if oxygen feedback system is switching lean-rich or if idle motor system is operational. The lamp also cannot be used to perform actuation test mode, sensor test mode or engine running test mode.
After all fault codes have been displayed, then power loss/check engine lamp can be used to verify switch function. The lamp will turn on and off as the switch is turned on and off.