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Home >> Mazda >> 2005 >> MX-5 Miata Base, Automatic >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Symptom Troubleshooting [Brakes) >> No.1 Abs Warning Light Or Brake System Warning Light Does Not Illuminate With Ignition Switch On >> Diagnostic procedure

Diagnostic procedure

NO.1 ABS WARNING LIGHT OR BRAKE SYSTEM WARNING LIGHT DOES NOT ILLUMINATE WITH IGNITION SWITCH ON - DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 CHECK TO SEE WHETHER MALFUNCTION IS IN COMMON POWER SUPPLY FOR ABS WARNING LIGHT OR OTHER WARNING LIGHTS 
Do either of the following warning lights illuminate when ignition switch is turned to ON position?
  • Air bag system warning light
  • Generator warning light
Yes Go to step 4.
No Go to next step.
2 INSPECT INSTRUMENT CLUSTER POWER SUPPLY FUSE 
Is instrument cluster ignition power supply fuse okay?
Yes Go to next step.
No Check for a short to ground on blown fuse's circuit.
Repair or replace as necessary.
Install appropriate amperage fuse.
*3 INSPECT WIRING HARNESS BETWEEN INSTRUMENT CLUSTER POWER SUPPLY AND INSTRUMENT CLUSTER FOR VOLTAGE 
Turn ignition switch to ON position.
Measure voltage at instrument cluster terminal 1C.
Is voltage approximately 12 V  ?
Yes Inspect ABS warning light circuits in instrument cluster (open circuit in instrument cluster).
No Repair wiring harness between fuse block and instrument cluster (Terminal 1C).
4 CHECK FOR OPEN CIRCUIT IN ABS HU/CM 
Do ABS warning light and BRAKE system warning light illuminate when the ignition switch is at ON position and the ABS HU/CM is disconnected?
Yes Go to next step.
No Go to Step 6.
5 CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT REOCCUR AFTER ABS HU/CM IS CONNECTED 
Reconnect ABS HU/CM.
Do ABS warning light and BRAKE system warning light illuminate when the ignition switch is at ON position?
Yes Temporary poor connection at ABS HU/CM). Terminals E and F.
Inspect ABS HU/CM connector and Terminals E and F.
No Replace ABS HU/CM (open circuit in ABS HU/CM).
6 INSPECT EACH WARNING LIGHT BULB 
Remove instrument cluster.
Inspect each warning light bulb.
Are they okay?
Yes Go to next step.
No Replace malfunction warning light bulb.
*7 CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN INSTRUMENT CLUSTER AND ABS HU/CM) OR INSTRUMENT CLUSTER 
CAUTION:
  • Attach a wire to the tester lead to avoid damaging the ABS HU/CM terminal.

Disconnect ABS HU/CM connector and instrument cluster connectors.
Is there continuity between instrument cluster terminals 1D and 3C and ABS HU/CM terminals E and F?
Yes Replace instrument cluster (open circuit in instrument cluster).
No Repair wiring harness between instrument cluster and ABS HU/CM (Terminal E or terminal F).