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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 MANUALSHONDA2005CIVIC L4-1.7L CNGREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSFUEL INJECTOR DRIVER MODULE (CNG)TESTING AND INSPECTION
2005 Honda Civic L4-1.7L CNG
Fuel Injector Driver Module (CNG): Testing and Inspection
2005 Honda Civic L4-1.7L CNGSECTION Testing and Inspection
Injector Control Module Circuit Troubleshooting
1. Turn the ignition switch OFF.
2. Disconnect the injector control module 26P connector.
3. Check for continuity between each injector control module terminal and body ground (see table).
Is there continuity?
YES - Repair short in the wire between the injector and the injector control module.
NO - Go to step 4.
4. Connect each injectors control module terminal to body ground with a jumper wire.
5. Check for continuity between body ground and the injector control module 26P connector terminals No.1, No.2, No. 14 and No.15.
Is there continuity?
YES - Go to step 6.
NO - Repair open in the wire between the injector and the injector control module.
6. Disconnect PCM connector A (31 P) and E (31P)
7. Check for continuity between body ground and the PCM connector terminals (see table).
Is there continuity?
YES - Repair short in the wire between the injector control module and PCM.
NO - Go to step 8.
8. Connect injector control module 26P connector terminals No.8, No.9, No.10, No.11, and No. 24 to body ground with a jumper wire (see table).
9. Check for continuity between body ground and the PCM connector terminals (see table).
Is there continuity?
YES - Go to step 10.
NO - Repair open in the wire between the injector control module and PCM.
10. Reconnect PCM connectors A (31 P) and E (31 P).
11. Turn the ignition switch ON (II), then measure voltage between body ground and injector control module 26P connector terminals No. 13, No.26, and injector 2P connector terminal No.1 within 2 seconds.
Is there battery voltage?
YES - Go to step 12.
NO - Do the injector relay circuit troubleshooting.
12. Check for continuity between body ground and injector control module 26P connector terminals No.3, No.12, No.16, and No.25 individually.
Is there continuity?
YES - Go to step 13.
NO - Repair open in wire(s) between the injector control module, G101, and the PCM.
13. Turn the ignition switch OFF.
14. Substitute a known-good injector control module and start the engine.
Does the engine start?
YES - Replace the original injector control module.
NO - Go to step 15.
15. Check for a clicking sound from the injectors.
Do all the injectors click?
YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck.
If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Go to step 16.
16. Turn the ignition switch OFF.
17. Remove the air cleaner.
18. Disconnect the injector 2P connectors.
19. Measure resistance between each injectors 2P connector terminals.
Is there 1.1 - 1.4 Ohms?
YES - Check for loose or corroded connectors at the injector control module.
NO - Replace the injector(s).
1. Turn the ignition switch OFF.
2. Disconnect the injector control module 26P connector.
3. Check for continuity between each injector control module terminal and body ground (see table).
Is there continuity?
YES - Repair short in the wire between the injector and the injector control module.
NO - Go to step 4.
4. Connect each injectors control module terminal to body ground with a jumper wire.
5. Check for continuity between body ground and the injector control module 26P connector terminals No.1, No.2, No. 14 and No.15.
Is there continuity?
YES - Go to step 6.
NO - Repair open in the wire between the injector and the injector control module.
6. Disconnect PCM connector A (31 P) and E (31P)
7. Check for continuity between body ground and the PCM connector terminals (see table).
Is there continuity?
YES - Repair short in the wire between the injector control module and PCM.
NO - Go to step 8.
8. Connect injector control module 26P connector terminals No.8, No.9, No.10, No.11, and No. 24 to body ground with a jumper wire (see table).
9. Check for continuity between body ground and the PCM connector terminals (see table).
Is there continuity?
YES - Go to step 10.
NO - Repair open in the wire between the injector control module and PCM.
10. Reconnect PCM connectors A (31 P) and E (31 P).
11. Turn the ignition switch ON (II), then measure voltage between body ground and injector control module 26P connector terminals No. 13, No.26, and injector 2P connector terminal No.1 within 2 seconds.
Is there battery voltage?
YES - Go to step 12.
NO - Do the injector relay circuit troubleshooting.
12. Check for continuity between body ground and injector control module 26P connector terminals No.3, No.12, No.16, and No.25 individually.
Is there continuity?
YES - Go to step 13.
NO - Repair open in wire(s) between the injector control module, G101, and the PCM.
13. Turn the ignition switch OFF.
14. Substitute a known-good injector control module and start the engine.
Does the engine start?
YES - Replace the original injector control module.
NO - Go to step 15.
15. Check for a clicking sound from the injectors.
Do all the injectors click?
YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck.
If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Go to step 16.
16. Turn the ignition switch OFF.
17. Remove the air cleaner.
18. Disconnect the injector 2P connectors.
19. Measure resistance between each injectors 2P connector terminals.
Is there 1.1 - 1.4 Ohms?
YES - Check for loose or corroded connectors at the injector control module.
NO - Replace the injector(s).
RENDER: 1.0x
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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.