If the check engine light is not working does it disable the ecu's ability to store codes? Car has a misfire under boost and when trying to read codes it comes up with nothing. I have checked/ replaced the bulb, traced the wiring back to the etacs unit and all is good. Anyone more familiar with the CEL wiring have any suggestions on where to check next? The OBD2 port works as Ive flashed tunes into the ecu.

 

The check engine "bulb" on the cluster is just one of many outputs that the ECU can control. As part of a "bulb check"- the ECU will generally flash the bulb for a brief moment when you key-on. Opening this circuit does nothing with the ability to store codes.

Your misfire may not be triggering the misfire monitor.

People tend to overcomplicate things when it comes to understanding computers. All they are is a device that takes many inputs- processes them and enables or disables certain outputs. Just because you can flash new software to the ECU does not mean that the ecu has (or does not have) the ability to control any output (like the CEL bulb). Each output is controlled by a transistor "driver" which can be individually damaged if the output current is too high for the transistor design.

 

I know not having the battery bulb in the cluster will keep the alternator from charging, was curious if the CEL bulb has a similar function with the ecus ability to store codes.

The CEL does not illuminate when having the key on in the accessory mode. I am ultimately trying to figure out why the CEL does not work/ turn on at all.

 

If it were a driver in the ecu, do you know which pin/ how I can confirm this is working properly?

 

The bulb in the cluster for the alternator is used as part of the current path to control the alternator turn on the for the field coil.

If you simply have an open circuit at your CEL bulb- just substitute a similar resistive load (like a small test light that draws similar amperage).

Typically when drivers fail- they do so because they've been exposed to higher-than "nominal" current draw for quite some time. Or- if there is a short on the circuit it can cook a driver almost immediately.