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2008 - MX-5 - Body and Accessories

NO.2 ALL ON-BOARD DIAGNOSTIC FUNCTIONS INOPERATIVE [KEYLESS ENTRY SYSTEM]



2

All on-board diagnostic functions inoperative

DESCRIPTION

  • Malfunction in keyless control module power supply circuit, door switch circuit, trunk lid compartment light circuit, keyless control module ground circuit, or keyless receiver.

POSSIBLE CAUSE

  • Malfunction in IG1 or B+ signal circuit of keyless control module

    • Keyless control module power supply fuse malfunction

    • Malfunction in wiring harness between keyless control module power supply fuses and keyless control module

  • Malfunction in door open/closed signal circuit of keyless control module

    • Door switch system malfunction

    • Keyless control module malfunction

    • Malfunction in wiring harness between keyless control module and door switch

  • Malfunction in trunk lid open signal circuit of keyless control module

    • Trunk lid compartment light switch system malfunction

    • Keyless control module malfunction

    • Malfunction in wiring harness between keyless control module and trunk lid compartment light switch

  • Malfunction in keyless control module GND signal circuit

    • Malfunction in wiring harness between keyless control module and ground

  • Malfunction in keyless receiver

    • Keyless receiver malfunction

    • Malfunction in wiring harness between keyless control module and keyless receiver


Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT KEYLESS CONTROL MODULE POWER SUPPLY FUSES

  • Are the keyless control module power supply fuses normal?

Yes

Go to the next step.

No

Inspect for a short to ground in circuit of blown fuse. Repair or replace if necessary.

Install an appropriate amperage fuse.

2

INSPECT DOOR SWITCH INSTALLATION

  • Are the door switches installed securely?

Yes

Go to the next step.

No

Install the door switches securely, then go back to step 5 of KEYLESS ENTRY SYSTEM PRELIMINARY INSPECTION.

*3

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN FUSE BLOCK AND KEYLESS CONTROL MODULE) OR ELSEWHERE

  • Turn the ignition switch to the ON position.

  • Measure the voltage at the following keyless control module connector terminals:

    • IG1 signal (terminal 3B)

    • B+ signal (terminal 1F)

  • Is the voltage B+?

Yes

Go to the next step.

No

Repair the wiring harness between the fuse block and keyless control module, then go to step 12.

*4

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (SHORT TO B+ BETWEEN FUSE BLOCK AND KEYLESS CONTROL MODULE, OR BETWEEN KEYLESS CONTROL MODULE AND GROUND) OR ELSEWHERE

  • Turn the ignition switch to the LOCK position.

  • Disconnect the keyless control module connector.

  • Measure the voltage at the following keyless control module connector terminal:

    • IG1 signal (terminal 3B)

  • Is the voltage B+?

Yes

Repair the malfunctioning wiring harness, then go to step 12.

No

Go to the next step.

*5

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS CONTROL MODULE AND GROUND) OR ELSEWHERE

  • Is there continuity between keyless control module connector terminal 3C and ground?

Yes

Go to the next step.

No

Repair the wiring harness between the keyless control module and ground, then go to step 12.

6

INSPECT FOR CHECK CODE 04 IN INSTRUMENT CLUSTER

Yes

Go to the next step.

No

Repair the door switch system using the DTC 04 inspection procedure, then go to step 12.

7

INSPECT KEYLESS CONTROL MODULE OR WIRING HARNESS (BETWEEN KEYLESS CONTROL MODULE AND DOOR SWITCHES, TRUNK LID COMPARTMENT LIGHT SWITCH FOR CONTINUITY)

  • Open the driver-side door.

  • Is there continuity between keyless control module connector terminal 4T, 4Q, 3Z and ground?

Yes

Replace the keyless control module and reprogram the keyless control module ID code, then go to the next step.

No

Repair the wiring harness between the keyless control module, door switches, and trunk lid compartment light switch, then go to the next step.

8

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN FUSE BLOCK AND KEYLESS RECEIVER) OR ELSEWHERE

  • Turn the ignition switch to the ON position.

  • Measure the voltage at the following keyless receiver terminal:

    • RF receiver power (terminal 1A)

  • Is the voltage B+?

Yes

Go to the next step.

No

Repair the wiring harness between the fuse block and keyless receiver, then go to step 12.

9

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND GROUND) OR ELSEWHERE

  • Is there continuity between keyless receiver connector terminal 1E and ground?

Yes

Go to the next step.

No

Repair the wiring harness between the keyless receiver and ground, then go to step 12.

10

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND KEYLESS CONTROL MODULE) OR ELSEWHERE

  • Turn the ignition switch to the ON position.

  • Disconnect the keyless receiver connector and keyless control module.

  • Is there continuity between the following terminals?

    • Terminal 1A—terminal 3S

    • Terminal 1C—terminal 3U

Yes

Go to the next step.

No

Repair the wiring harness between the keyless receiver and keyless control module, then go to step 12.

11

INSPECT IF MALFUNCTION IS IN WIRING HARNESS (NO CONTINUITY BETWEEN KEYLESS RECEIVER AND KEYLESS CONTROL MODULE) OR KEYLESS CONTROL MODULE

  • Measure the signal wave pattern for keyless receiver terminal 1C using an oscilloscope when the transmitter is operated with the key not inserted into the ignition key cylinder.

  • Does the wave pattern change when the transmitter is operated?

    NOTE:

    • Perform the oscilloscope setting using 0.5V/DIV (Y), 100ms/DIV (X), DC range.

Yes

Replace the keyless control module, then go to the next step.

(See KEYLESS CONTROL MODULE REMOVAL/INSTALLATION [KEYLESS ENTRY SYSTEM].)

No

Replace the keyless receiver, then go to the next step.

(See KEYLESS RECEIVER REMOVAL/INSTALLATION [ADVANCED KEYLESS SYSTEM].)

12

REINSPECT MALFUNCTION SYMPTOM AFTER REPAIR

  • Does the keyless entry system operate properly?

Yes

Troubleshooting completed.

Explain repairs to the customer.

No

Reinspect the malfunction symptoms, then repeat from step 1 if the malfunction recurs.




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