18-036-20

Flash: Powertrain Control Module (PCM) Updates This bulletin involves reprogramming the PCM with the latest available software. This bulletin fixes all vehicles listed and also contains an optional software path for situations where the customer is specifically complaining of a drone noise, shudder, pulsation, or vibration under light throttle applications, while vehicle is operating in Multi Displacement System/Economics (MDS/ECO) mode (optionalsoftware available for D2&DJ vehicles).There will be two separate software options displayed on the wiTECH flash tab. The software file released for this condition contains the verbiage ?MDS NOISE?. The other file is the standard software that does not contain improvements for the drone/shudder concern. If for some reason the customer finds this shudder improvementobjectionable, the PCM software may be returned/reflashed to the standard version.Both software versions will address the remaining conditions noted in the bulletin.The customer may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic Trouble Codes (DTCs):P3402 - Cylinder 1 Deactivation Control Performance. P3426 - Cylinder 4 Deactivation Control Performance. P3442 - Cylinder 6 Deactivation Control Performance. P3450 - Cylinder 7 Deactivation Control Performance. P0128 - Thermostat Rationality. Customers may also describe the following condition:Heater not warming cabin sufficiently and engine slow to warm up. This condition could be caused by a malfunctioning thermostat which is not associated with an HVAC issue.