* Poor Ground Connection: This is the most common culprit. A bad ground connection between the engine block and the chassis, or between the chassis and the battery negative terminal, can prevent sufficient current from reaching the starter motor. Clean all ground points thoroughly, making sure there's bare metal contact. Consider adding a dedicated ground wire directly from the engine block to the battery negative terminal.
* Power Wire Issue: Check the positive wire from the battery to the starter solenoid. Ensure it's clean, securely connected at both ends, and has no internal breaks or corrosion. A high resistance in this wire can prevent enough current from flowing.
* Ignition Switch Problem: The ignition switch needs to send power to the starter solenoid to engage it. A faulty ignition switch, or a wiring problem in the circuit leading to it, could be preventing the signal from reaching the solenoid.
* Neutral Safety Switch: In most cars, including likely your CRX, a neutral safety switch prevents starting unless the transmission is in neutral or park. A faulty switch or its wiring can prevent the starter from engaging. Test the continuity of this switch according to your car's wiring diagram.
* Starter Solenoid Internals (despite bench test): While you bench tested the solenoid, there might be a subtle internal failure that only appears under the load and vibration of the car. A weak spring or a poor contact within the solenoid itself could be to blame. This is less likely if it worked on the bench, but possible.
* Wiring Harness Issue: Inspect the wiring harness leading to the starter for any damage, chafing, or corrosion. A broken wire, a short circuit, or high resistance anywhere in the harness can prevent the starter from working.
Troubleshooting Steps:
1. Check all grounds: Start here. This is the most frequent cause.
2. Check the positive cable: Inspect and test the cable from the battery to the starter.
3. Inspect the wiring harness: Look for any damage or corrosion.
4. Test the neutral safety switch: Use a multimeter to test continuity according to your car's wiring diagram.
5. Test the ignition switch: Verify that power is reaching the starter solenoid when the ignition key is turned to the start position. Use a test light or multimeter.
6. If all else fails: Try swapping in a known good starter motor from a similar CRX to confirm if the problem lies with the starter motor itself.
Remember to disconnect the negative battery terminal before performing any electrical tests or repairs to prevent short circuits and potential injury. Use a wiring diagram specific to your CRX model year for accurate testing and component location.
