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.
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HOMESERVICE MANUALSMAZDA1999626 ES, 2.5 D, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SELF-DIAGNOSTICSDIAGNOSTIC TESTSDTC P1650: POWER STEERING PRESSURE (PSP) SWITCHCONDITION
1999 Mazda 626 ES, 2.5 D, Standard
DTC P1650: Power Steering Pressure (PSP) Switch: Condition
1999 Mazda 626 ES, 2.5 D, StandardSECTION Condition
DTC P1650 indicates PSP signal is out of self-test range. Possible causes for this fault are as follows:
- Open or short in wiring harness.
- Faulty PSP switch.
- Faulty PSP switch/shorting bar damage.
- Faulty Powertrain Control Module (PCM).
- Verify Electrical Function
Ensure freeze frame data is recorded. Start engine and allow to idle. Using scan tool, access PSP PID (if scan tool cannot access PSP PID, go to next step). Turn steering wheel left, then right. If scan tool does not indicate on/off switching, go to next step. If scan tool indicates on/off switching, ensure all applicable connections are clean and tight, and go to DIAGNOSTIC TEST Z (INTERMITTENT) . - Check PSP Switch Operation
Turn ignition off. Install tachometer. Start engine and allow to idle. Disconnect PSP switch. Connect jumper wire between harness terminal and ground. If engine speed increases, replace switch and repeat QUICK TEST . If engine speed does not increase, go to next step. - Check PSP Circuit Resistance
Turn ignition off. Disconnect jumper wire. Leave PSP switch disconnected. Turn ignition off. Disconnect 104-pin PCM connector. Inspect connector for damage and repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 31 (PSP) at breakout box and PSP terminal of PSP switch connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, repair open circuit and repeat QUICK TEST . - Check For Short In PSP Circuit
Leave ignition off and PSP switch disconnected. Measure resistance between test pins No. 31 (PSP) and 91 at breakout box. Measure resistance between test pin No. 31 and chassis ground. If both resistance measurements are 10 k/ohms or more, go to next step. If resistance is less than 10 k/ohms, repair short circuit and repeat QUICK TEST . - Check Switch Resistance
Turn ignition off. Disconnect PSP switch. Start engine and allow to idle. Measure resistance between PSP switch signal and chassis ground while turning steering wheel. If resistance is less than 10 ohms, replace PCM and repeat QUICK TEST . If resistance is 10 ohms or more, replace PSP switch and repeat QUICK TEST .
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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.