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.
Starter Switch Signal Circuit Troubleshooting
2004 Honda S2000 L4-2.2LSECTION Starter Switch Signal Circuit Troubleshooting
Starter Switch Signal Circuit Troubleshooting
NOTE: The clutch pedal must be pressed.
1. Measure voltage between ECM connector terminals A24 and B20 with the ignition switch in the ON (II) position and the engine start button pressed.
Is there battery voltage?
YES - The starter switch signal is OK.
NO - Go to step 2.
2. Inspect the No. 21 STARTER SIGNAL (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK ?
YES - Repair open in the wire between the ECM (A24) and the No. 21 STARTER SIGNAL (7.5 A) fuse.
NO - Repair short in the wire between the ECM (A24) and the No. 21 STARTER SIGNAL (7.5A) fuse or the PGM-FI main relay. Replace the No. 21 STARTER SIGNAL (7.5 A) fuse.
NOTE: The clutch pedal must be pressed.
1. Measure voltage between ECM connector terminals A24 and B20 with the ignition switch in the ON (II) position and the engine start button pressed.
Is there battery voltage?
YES - The starter switch signal is OK.
NO - Go to step 2.
2. Inspect the No. 21 STARTER SIGNAL (7.5 A) fuse in the under-dash fuse/relay box.
Is the fuse OK ?
YES - Repair open in the wire between the ECM (A24) and the No. 21 STARTER SIGNAL (7.5 A) fuse.
NO - Repair short in the wire between the ECM (A24) and the No. 21 STARTER SIGNAL (7.5A) fuse or the PGM-FI main relay. Replace the No. 21 STARTER SIGNAL (7.5 A) fuse.
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.