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HOMESERVICE MANUALSMAZDA2006B4000 BASE, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE SYMPTOM TROUBLESHOOTING - (5 OF 5)GENERAL TEST INDEXGENERAL PINPOINT TEST 2: TACHOMETER OUTPUT (CTO) FAILURE
2006 Mazda B4000 Base, Automatic

General Pinpoint Test 2: Tachometer Output (CTO) Failure

2006 Mazda B4000 Base, AutomaticSECTION General Pinpoint Test 2: Tachometer Output (CTO) Failure
GENERAL PINPOINT TEST 2: TACHOMETER OUTPUT (CTO) FAILURE

PINPOINT TEST 2 TACHOMETER OUTPUT (CTO) FAILURE
STEP INSPECTION ACTION
1 CHECK CTO CIRCUIT FOR SHORT TO POWER
  • Install breakout box, leave powertrain control module (PCM) disconnected.
  • Key ON, Engine OFF (KOEO).
  • Measure voltage of CTO circuit between test pin 48 at breakout box and ground.
  • Key OFF.
  • Is voltage less than 0.5 volt? 
 Yes Go to next step.
No Repair short circuit. Verify symptom no longer exists.
2 CHECK CTO CIRCUIT FOR SHORT TO GROUND IN HARNESS
  • Disconnect PCM.
  • Disconnect instrument cluster connector 0922-102.
  • Measure resistance between test pin 48 (CTO SIG) and test pins 51, 76, 77 or 103 (PWR GND) and chassis ground.
  • Measure resistance between test pin 48 (CTO SIG) and chassis ground.
  • Are both resistances greater than 10, 000 ohms? 
 Yes Go to next step.
No Repair short in harness. Verify a symptom no longer exists.
3 CHECK CTO CIRCUIT FOR OPEN HARNESS
  • Measure the resistance of CTO circuit (T/Y) between test pin 48 at breakout box and pin 6 of instrument cluster connector 0922-102.
  • Is the resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open circuit. Verify symptom no longer exists.
4 CHECK CTO SIGNAL FROM PCM
  • Connect PCM.
  • Key ON, Engine Running (KOER).
  • Measure voltage of CTO circuit (T/Y) between pin 6 of instrument cluster connector 0922-102 and ground.
  • Is voltage reading between 3.0 and 9.0 volts? 
 Yes See SYMPTOM TROUBLESHOOTING CHART - INSTRUMENT CLUSTER AND PANEL ILLUMINATION .
No Open or short in PCM. Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Verify symptom no longer exists.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.