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.
Pinpoint Test B: Powertrain Control Module (PCM) Power Relay: Introduction
This pinpoint test is intended to diagnose the following:
- harness circuits: B+, IGN START/RUN, INJPWRM, ISP-R, ISP-R/S, PCMRC and VPWR
- PCM power relay (12A646)
- PCM (12A650)
| Pin | Circuit |
|---|---|
| 2 | IGN START/RUN (Ignition START/RUN) |
| Pin | Circuit |
|---|---|
| 5 | VPWR (Vehicle Power) |
| 2 | PCMRC (PCM Relay Control) |
| 1, 3 | B+ (Battery Positive Voltage) |
| Pin | Circuit |
|---|---|
| 9 | ISP-R (Ignition Switch Position Run) |
| Pin | Circuit |
|---|---|
| B67, B68 | VPWR (Vehicle Power) |
| B21 | INJPWRM (Injector Power Monitor) |
| B39 | ISP-R/S (Ignition Run/Start Input) |
| B38 | PCMRC (PCM Relay Control) |
| B42 | ISP-R (Ignition Switch Position Run) |
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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.
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