There should be a built-in LED and button, however this ONLY displays blink codes from the DM (Diagnostic Module), which only has codes related to the CEL. If the CEL is not illuminated (and the bulb in the cluster is good), there are probably no codes here. Even if codes are present, the important ones will be on the two LH modules, two E-GAS modules, two EZL's, and ASR module. A hand-held blinker box (or, SDS) is needed to view & clear codes from all those other modules.