Active Control Engine Mount System: Highlander
- Check vacuum hoses for active control engine mount system for looseness, damage, restrictions or being disconnected. See Fig 1. Ensure cap is installed on end of vacuum hose "C". See Fig 1. If cap is missing from vacuum hose "C" or vacuum hose "C" is damaged, replace vacuum hose "C" as an assembly. DO NOT repair this vacuum hose by cutting and splicing in another vacuum hose. If all vacuum hoses and connections are okay, go to next step. If vacuum hoses and connections are defective, repair or replace components as necessary.
- Start engine. Warm engine to normal operating temperature. Connect Toyota hand-held tester to data link connector No. 3. See Figure. Turn hand-held tester on. Select ACM INHIBIT ACTIVE TEST on hand-held tester. Place transaxle in Park or Neutral. Check whether or not engine vibration increases while ACM INHIBIT ACTIVE TEST is in the ON state. If engine vibration increases while ACM INHIBIT ACTIVE TEST is in the ON state, shut engine off. Remove hand-held tester. Go to next step. If engine vibration does not increase while ACM INHIBIT ACTIVE TEST is in the ON state, shut engine off. Remove hand-held tester. Go to step 4.
- Start engine. Warm engine to normal operating temperature. Chock all 4 wheels and apply parking brake. Depress brake and place transaxle in Drive. Disconnect vacuum hose "A" at upper cap on air cleaner assembly. See Fig 1. Place your finger over end of disconnected vacuum hose "A" and check that suction exists intermittently. If suction does not exist intermittently, shut engine off. Reinstall vacuum hose "A" on upper cap on air cleaner assembly. Go to next step. If suction exists intermittently, shut engine off. Reinstall vacuum hose "A" on upper cap on air cleaner assembly. Active control engine mount system is operating properly.
- Remove glove box for access to Engine Control Module (ECM). For illustration of ECM location, see THEORY & OPERATION article. Connect oscilloscope leads between terminal ACM1 (Black wire) on ECM electrical connector E7 and terminal E1 (Brown wire) on ECM electrical connector E8. See Fig 2.
- Start engine. Warm engine to normal operating temperature. Apply parking brake. Note voltage reading on oscilloscope with transaxle in proper gear position and in accordance with engine speed. See VOLTAGE SPECIFICATIONS table. If voltage is not as specified, shut engine off. Remove oscilloscope. Go to next step. If voltage is as specified, shut engine off. Remove oscilloscope. Go step 11.VOLTAGE SPECIFICATIONS
Condition Voltage Transaxle In Park 9-14 Transaxle In Drive With Engine Speed 900 RPM Or More 9-14 Transaxle In Drive With Engine Speed Less Than 900 RPM (1)
.(1) Voltage should pulse at intervals. See Fig 2 - Disconnect electrical connector at Active Control Mount Vacuum Switching Valve (ACM VSV). ACM VSV is located near active control engine mount at the front (radiator side) of the engine, just below exhaust manifold. See Fig 1. Using ohmmeter, check resistance between electrical terminals on ACM VSV. Resistance should be 19-21 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace ACM VSV.
- Ensure electrical connector at ACM VSV is still disconnected. Remove EFI main relay from fuse/relay box at driver's side front corner of engine compartment, near battery. See Fig 3. EFI main relay may also be referred to as EFI relay. To check for open in wiring between EFI main relay and ACM VSV, using ohmmeter, check resistance between cavity No. 3 (Black/White wire) in fuse/relay box for EFI main relay and terminal No. 1 (Black/White wire) on electrical connector for ACM VSV. See Fig 3. If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair open on Black/White wire between EFI main relay and ACM VSV. See WIRING DIAGRAMS article.
- To check for short in wiring between EFI main relay output circuit and ground, using ohmmeter, check for continuity between cavities No. 2 (White/Black wire) and No. 3 (Black/White wire) in fuse/relay box for EFI main relay. See Fig 3. If no continuity exists, go to next step. If continuity exists, repair short in EFI main relay output circuit and ground between cavities No. 2 (White/Black wire) and No. 3 (Black/White wire) in fuse/relay box for EFI main relay. See WIRING DIAGRAMS article.
- Ensure ignition is off. Disconnect ECM electrical connector E7. See Fig 2. To check for open in wiring between ECM and ACM VSV, using ohmmeter, check resistance between terminal ACM1 (Black wire) on ECM electrical connector E7 and terminal No. 2 (Black wire) on ACM VSV electrical connector. See Fig 2 and Fig 3 . If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair open on Black wire between ECM and ACM VSV. See WIRING DIAGRAMS article.
- To check for short in wiring between ECM and ACM VSV, using ohmmeter, check for continuity between terminal ACM1 (Black wire) on ECM electrical connector E7 and terminal E1 (Brown wire) on ECM electrical connector E8. See Fig 2. If continuity exists, repair short to ground in Black wire between ECM and ACM VSV. See WIRING DIAGRAMS article. If no continuity exists, check ECM ground circuit. See WIRING DIAGRAMS article. If ECM ground circuit is okay, replace ECM. If ECM is replaced and vehicle is equipped with engine immobilizer system, ECM must be programmed with proper ignition key code for engine immobilizer system. Models equipped with engine immobilizer system may be identified by looking at the ignition key. On models equipped with engine immobilizer system, the top of the ignition key is thicker than a standard ignition key, as a transponder chip is incorporated into the top of the ignition key. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.
- Remove Active Control Mount Vacuum Switching Valve (ACM VSV). ACM VSV is located near active control engine mount at the front (radiator side) of the engine, just below exhaust manifold. See Fig 1. Apply air pressure to port "G" on ACM VSV. Ensure air flows from ports "E" and "H". Perform STEP 1 in illustration. See Figure. Apply battery voltage and ground to electrical terminals on ACM VSV. Apply air pressure to port "F" on ACM VSV. Ensure air flows from ports "E" and "H". Perform STEP 2 in illustration. See Figure. If ACM VSV operates properly, reinstall ACM VSV. Go to next step. If ACM VSV does not operate properly, replace ACM VSV.
- Disconnect vacuum hose from vacuum fitting on active control engine mount and connect vacuum pump to vacuum fitting. See Fig 4. Using vacuum pump, apply 25.0 in. Hg of vacuum to active control engine mount for at least one minute and check that no change exists is the needle movement. Needle is located at the bottom of active engine control mount. See Fig 4. Check for signs of fluid leakage on active engine mount. If active control engine mount operates properly, active control engine mount system is operating properly. If active control engine mount does not operate as specified or signs of fluid leakage exist, replace active control engine mount.