Engine Mount: Testing and Inspection
Engine Mount Control System Troubleshooting
Special Tools Required
- Vacuum pump/gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available
NOTE: Check the vacuum hoses and lines for damage and proper connections before troubleshooting.
Follow this procedure if the engine vibrates excessively when idling.
1. Remove the engine compartment covers. Service and Repair
2. Start the engine, and let it idle.
3. Raise the engine speed from idling to 2,000 rpm.
4. Check the MOUNT CTRL SOL in the PGM-FI DATA LIST with the Honda Diagnostic System (HDS).
Is ON indicated at idling and OFF indicated at 2,000 rpm?
YES - Go to step 5.
NO - Update the powertrain control module (PCM) if it does not have the latest software, ECM/PCM Update or substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the engine mount control system works properly, and the PCM was updated, the troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair
5. Turn the ignition switch to LOCK (0).
6. Disconnect the engine mount control solenoid valve 2P connector from the engine mount control solenoid valve.
7. Turn the ignition switch to ON (II).
8. Measure the voltage between engine mount control solenoid valve 2P connector terminal No. 2 and body ground.
Is there battery voltage?
YES - Go to step 9.
NO - Repair open in the wire between engine mount control solenoid valve 2P connector terminal No. 2 and No. 7 (15 A) fuse in the driver's under-dash fuse/relay box.
9. Start the engine, and let it idle.
10. Measure the voltage between engine mount control solenoid valve 2P connector terminals No. 1 and No. 2, with the engine at idle.
Is there battery voltage?
YES - Go to step 11.
NO - Repair open in the wire between PCM terminal A12 and engine mount control solenoid valve 2P connector terminal No. 1. If the wire is OK, update the PCM if it does not have the latest software, ECM/PCM Update or substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes and recheck. If the engine mount control system works properly, and the PCM was updated, the troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair
11. Raise the engine speed above 2,000 rpm.
12. Measure the voltage between engine mount control solenoid valve 2P connector terminals No. 1 and No. 2.
Is there battery voltage?
YES - Repair short to body ground in the wire between PCM terminal A12 and engine mount control solenoid valve 2P connector terminal No. 1. If the wire is OK, update the PCM if it does not have the latest software, ECM/PCM Update or substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes and recheck. If the engine mount control system works properly, and the PCM was updated, the troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair
NO - Reconnect the engine mount control solenoid valve 2P connector, then go to step 13.
13. Turn the ignition switch to LOCK (0).
14. Disconnect the vacuum hose (A) from the engine mount control solenoid valve (B), and connect a vacuum pump/gauge, 0-30 inHg, to the hose. Apply about 20 inHg of vacuum, and wait for 20 seconds.
Do both engine mounts hold vacuum?
YES - Reconnect the vacuum hose, then go to step 17.
NO - Reconnect the vacuum hose, then go to step 15.
15. Disconnect the vacuum hose (A) from the three way valve, and connect a vacuum pump/gauge, 0-30 inHg, to the hose. Apply about 20 inHg of vacuum, and wait for 20 seconds.
Does the front engine mount hold vacuum?
YES - Go to step 16.
NO - The vacuum hose or the front engine mount has a vacuum leak. Repair as needed.
16. Disconnect the vacuum hose (A) from the three way valve, and connect a vacuum pump/gauge, 0-30 inHg, to the hose. Apply about 20 inHg of vacuum, and wait for 20 seconds.
Does the rear engine mount hold vacuum?
YES - Repair the vacuum hose (B) between the engine mount control solenoid valve and the three way valve.
NO - The vacuum hose or the rear engine mount has a vacuum leak. Repair as needed.
17. Disconnect the vacuum hose (A) from the three way valve. Block the open port, then connect the vacuum pump to the vacuum hose.
18. Start the engine and let it idle, then apply vacuum to the mount.
Is there a noticeable change in idle smoothness with and without vacuum applied?
YES - Reconnect the vacuum hose to the three way valve, then go to step 19.
NO - Replace the front engine mount. Front Engine Mount Removal/Installation
19. Disconnect the vacuum hose (A) from the three way valve. Block the open port, then connect the vacuum pump to the vacuum hose.
Is there a noticeable change in idle smoothness with and without vacuum applied?
YES - Reconnect the vacuum hose to the three way valve, then go to step 20.
NO - Replace the rear engine mount. Rear Engine Mount Removal/Installation
20. Connect a vacuum pump/gauge, 0-30 inHg, to the engine mount control solenoid valve (A).
Is there manifold vacuum at idle, and a decrease in manifold vacuum when you raise the engine speed above 2,000 rpm?
YES - The system is OK.
NO - Repair the vacuum hose (B) between the intake manifold and the engine mount control solenoid valve. If the vacuum hose is OK, replace the engine mount control solenoid valve.
