DTC U0515:41 [BCM]

2016 – MX-5 – Body and Accessories

Description	Error signal received from start stop unit
Detection condition	Check sum error occurred on communication with the BCM and the start stop unit 3 times continuously with the ignition switched ON (engine off or on).
Fail-safe	Exterior lighting system Turn the TNS (parking lights) and headlights LO on, and turn off other exterior light controls. Auto light system Continue the controls prior to the auto light malfunction detection. Wiper system Continue the controls prior to the wiper malfunction detection. Washer system Stop the washer control. Auto wiper system Continue the controls prior to the wiper malfunction detection.
Possible cause	DTCs are stored in the start stop unit. Start stop unit malfunction BCM malfunction
System wiring diagram	Not applicable

Diagnostic Procedure

Step	Inspection		Action
1	VERIFY BCM DTCs AGAIN Clear the DTC for the BCM using the M-MDS. (See CLEARING DTC [BCM].) Retrieve the BCM DTCs using the M-MDS. (See DTC INSPECTION [BCM].) Is the same DTC displayed?	Yes	Go to the next step.
		No	Go to Step 5.
2	VERIFY START STOP UNIT DTCs Retrieve the start stop unit DTCs using the M-MDS. (See DTC INSPECTION [START STOP UNIT].) Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [START STOP UNIT].)
		No	Go to the next step.
3	VERIFY IF MALFUNCTIONING LOCATION IS START STOP UNIT DEPENDING ON REPEATABILITY Clear the DTC for the BCM using the M-MDS. (See CLEARING DTC [BCM].) Retrieve the BCM DTCs using the M-MDS. (See DTC INSPECTION [BCM].) Is the same DTC displayed?	Yes	Replace the start stop unit, then go to the next step. (See START STOP UNIT REMOVAL/INSTALLATION.)
		No	Go to Step 5.
4	VERIFY THAT REPAIRS HAVE BEEN COMPLETED Clear the DTC for the BCM using the M-MDS. (See CLEARING DTC [BCM].) Retrieve the BCM DTCs using the M-MDS. (See DTC INSPECTION [BCM].) Is the same DTC displayed?	Yes	Replace the BCM, then go to the next step. (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION.)
		No	Go to the next step.
5	VERIFY IF OTHER DTCs DISPLAYED Are any other DTCs displayed?	Yes	Repair or replace the malfunctioning part according to the applicable DTC troubleshooting. (See DTC TABLE [BCM].)
		No	DTC troubleshooting completed.