Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 47 (ENGINE CONTROLS - SELF-DIAGNOSTICS)SYSTEM TESTSPCM POWER RELAY
2008 Mazda 6 s Sport, 4D Hatchback, Standard
Pcm Power Relay
2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION Pcm Power Relay
WARNING: This page is about a different car, the 2002 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
- Check VPWR Circuit Resistance
Disconnect Idle Air Control (IAC) valve harness connector. Disconnect scan tool from DLC. Disconnect PCM power relay (located in battery junction box). Measure resistance of VPWR circuit between IAC valve harness connector terminal (White/Red wire) and PCM Power Relay battery junction box terminal (Red wire). See WIRING DIAGRAMS article. If resistance is less than 5.0 ohms, reconnect IAC valve and go to next step. If resistance reading is 5.0 ohms or more, repair open in VPWR circuit between PCM power relay (Red wire) and IAC valve (White/Red wire). After repair, restore vehicle to original condition and rerun QUICK TEST under SELF-DIAGNOSTIC SYSTEM. - Check B+ And IGN START/RUN Voltage To PCM Power Relay
Measure B+ circuit (Red/Light Green wire) voltage at the PCM power relay connector. Turn ignition on, engine off. Measure IGN START/RUN circuit (White/Violet wire) voltage at PCM Power Relay battery junction box terminal. If both voltages are more than 10.5 volts, go to next step. If both voltages are 10.5 volts or less, repair open in B+ (Red/Light Green wire) or IGN START/RUN circuit (White/Violet wire). After repair, restore vehicle to original condition and rerun QUICK TEST under SELF-DIAGNOSTIC SYSTEM. - Check Ground Circuit To Power Relay
Measure voltage between B+ circuit (Red/Light Green wire) and ground circuit (Black wire) at PCM Power Relay battery junction box terminal. Turn ignition off. If voltage reading was more than 10.5 volts, replace PCM. After repair, restore vehicle to original condition and rerun QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If voltage reading was 10.5 volts or less, repair open in ground circuit. After repair, restore vehicle to original condition and rerun QUICK TEST under SELF-DIAGNOSTIC SYSTEM.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.