Engine Mount Control System: Troubleshooting

Special Tools Required

Vacuum pump/gauge, 0-30 in.Hg A973X-041-XXXXX

NOTE:

Check the vacuum hoses and lines for damage and proper connections before troubleshooting.
Before performing engine mount control system troubleshooting, check for damage to the suspension, subframe, body, or exhaust.

Follow this procedure if the engine vibrates excessively when idling.

Warm up the engine to normal operating temperature (the cooling fan comes on two times).
Is the idle speed less than 730 RPM?
1. YES - Go to step 2.
2. NO - Adjust the idle speed (see appropriate ON-VEHICLE ADJUSTMENTS article ).
Fully press the brake pedal.
With the transmission in gear, have an assistant disconnect and reconnect the 2P connector at the engine mount control solenoid valve.
Is there a noticeable change in idle smoothness when the engine mount control solenoid valve 2P connector is disconnected?
1. YES - Reconnect the engine mount control solenoid valve 2P connector to the solenoid valve. The engine mount control system is OK.
2. NO - Go to step 4.
Shift the transmission to P or N.
Disconnect the engine mount control solenoid valve 2P connector from the engine mount control solenoid valve.
Measure voltage between the No. 2 terminal and body ground.

Fig 1: Measuring Voltage Between The No. 2 Terminal & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 7.
2. NO - Repair an open in the wire between the engine mount control solenoid valve connector and No. 6 (15A) fuse in the under-dash driver's fuse/relay box.
Measure voltage between the engine mount control solenoid valve 2P connector No. 1 terminal and No. 2 terminal.

Fig 2: Measuring Voltage Between The Engine Mount Control Solenoid Valve 2P Connector No. 1 Terminal & No. 2 Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 8.
2. NO - Repair an open in the wire between powertrain control module (PCM) connector terminal A2 (1999-2000, 2002-2004 models) or E24 (2001 model) and the engine mount control solenoid valve connector. If the wire is OK, substitute a known-good PCM and recheck (see appropriate REMOVAL, OVERHAUL & INSTALLATION article ).
Raise the engine speed above 1,000 RPM.
Measure voltage between the engine mount control solenoid valve 2P connector No. 1 terminal and No. 2 terminal.

Fig 3: Measuring Voltage Between The Engine Mount Control Solenoid Valve 2P Connector No. 1 Terminal & No. 2 Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Repair a short to body ground in the wire between PCM connector terminal A2 (1999-2000, 2002-2004 models) or E24 (2001 model) and the engine mount control solenoid valve connector. If the wire is OK, substitute a known-good PCM and recheck (see appropriate REMOVAL, OVERHAUL & INSTALLATION article ).
2. NO - Go to step 10.
Connect the engine mount control solenoid valve 2P connector.
Disconnect the upper vacuum hose (A) from the engine mount control solenoid valve (B), and connect a vacuum pump/gauge to the hose. Apply vacuum for 20 seconds.

Fig 4: Disconnecting Upper Vacuum Hose
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Does the engine mount hold vacuum?
1. YES - Go to step 12.
2. NO - Either the vacuum hose or front engine mount has a vacuum leak. Repair as needed.
Release the vacuum, then apply vacuum again.
Is there a noticeable change in idle smoothness with and without vacuum applied?
1. YES - Go to step 13.
2. NO - Replace the front engine mount.
Disconnect the upper vacuum hose (A) from the engine mount control solenoid valve (B) and connect a vacuum pump/gauge to a hose connected to the engine mount control valve.

Fig 5: Disconnecting Upper Vacuum Hose
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there manifold vacuum at idle, and a decrease in manifold vacuum when you raise the engine speed above 1,000 RPM?
1. YES - Replace the engine mount control solenoid valve.
2. NO - A hose is restricted or the intake manifold part is plugged.