Check Code 18

WARNING: This page is about a different car, the 2007 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

CHECK CODE 18

Check code 18	Ignition key illumination control signal
INSPECTION CONDITION	DISPLAY	ACTION
After selecting check code 18, wait approx. 2 s.	Courtesy of MAZDA MOTORS CORP.	Ignition key illumination flashes three times.	The ignition key illumination is normal.
After selecting check code 18, wait approx. 2 s.	Courtesy of MAZDA MOTORS CORP.	Except above	Verify that the voltage of instrument cluster terminal 1K is B+. If the voltage is as specified, replace the instrument cluster. If the voltage is not as specified, inspect the following parts: Ignition key illumination bulb Wiring harness (Battery-ignition key illumination-instrument cluster)