Determination Procedure

WARNING: This page is about a different car, the 2020 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

When disconnecting the connector, verify that there is no looseness, damage, deformation, corrosion, or poor connection of the connector terminals.
When inspecting the DLC-2, touch it with a paper clip or similar thin pin without directly inserting a tester into the terminals.

DETERMINATION PROCEDURE

STEP	Inspection		ACTION
1	INSPECT BETWEEN INSTRUMENT CLUSTER AND CONNECTOR C-40 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Disconnect the connector C-40. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Switch the ignition ON (engine off). Measure the voltage at instrument cluster terminals C and E. Is the voltage at instrument cluster terminals C and E the same?	Yes	Go to the next step.
1		No	Go to Step 3.
2	INSPECT INSTRUMENT CLUSTER FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Disconnect the instrument cluster connector. Inspect for continuity between instrument cluster terminals C and E (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the instrument cluster and connector C-40 because the wiring harness is shorted between circuits.
2		No	Replace the instrument cluster because there is a short between circuits in the instrument cluster. (See INSTRUMENT CLUSTER REMOVAL/INSTALLATION .)
3	INSPECT BETWEEN CONNECTOR C-40 AND DLC-2 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Inspect for continuity between DLC-2 terminals L and K. Is there continuity?	Yes	Repair or replace the wiring harness between connector C-40 and DLC-2 because the wiring harness is shorted between circuits.
3		No	Go to the next step.
4	INSPECT BETWEEN CONNECTOR C-40 AND CONNECTOR C-14 FOR SHORT BETWEEN CIRCUITS Disconnect the connector C-14. Connect the connector C-40. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Switch the ignition ON (engine off). Measure the voltage at DLC-2 terminals L and K. Is the voltage at DLC-2 terminals L and K the same?	Yes	Repair or replace the wiring harness between connector C-40 and connector C-14 because the wiring harness is shorted between circuits.
4		No	Go to the next step.
5	INSPECT BETWEEN CLIMATE CONTROL UNIT AND CONNECTOR C-14 FOR SHORT BETWEEN CIRCUITS Measure the voltage at climate control unit terminals D and B. Is the voltage at climate control unit terminals D and B the same?	Yes	Go to Step 8.
5		No	Go to the next step.
6	INSPECT BETWEEN BLIND SPOT MONITORING (BSM) CONTROL MODULE (LH) AND CONNECTOR C-26 FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Disconnect the connector C-26. Inspect the continuity between blind spot monitoring (BSM) control module (LH) terminals D and E. Is there continuity?	Yes	Go to the next step.
6		No	Repair or replace the wiring harness between connector C-14 and connector C-26 because the wiring harness is shorted between circuits.
7	INSPECT BLIND SPOT MONITORING (BSM) CONTROL MODULE (LH) FOR SHORT BETWEEN CIRCUITS Disconnect the blind spot monitoring (BSM) control module (LH) connector. Inspect for continuity between blind spot monitoring (BSM) control module (LH) terminals D and E (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the blind spot monitoring (BSM) control module (LH) and connector C-26 because the wiring harness is shorted between circuits.
7		No	Replace the blind spot monitoring (BSM) control module (LH) because there is a short between circuits in the blind spot monitoring (BSM) control module (LH). (See BLIND SPOT MONITORING (BSM) CONTROL MODULE REMOVAL/INSTALLATION .)
8	INSPECT CLIMATE CONTROL UNIT FOR SHORT BETWEEN CIRCUITS Switch the ignition off. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .) Disconnect the climate control unit connector. Inspect for continuity between climate control unit terminals D and B (wiring harness side). Is there continuity?	Yes	Repair or replace the wiring harness between the climate control unit and connector C-14 because the wiring harness is shorted between circuits.
8		No	Replace the climate control unit because there is a short between circuits inside the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER] .)