How to Exclude the Engine Braking Failures?

The malfunctions of the  automobile engine braking may appeared in daily car driving. In the car driving, when the shift handle is in the 2, 1, S or L gear, then release the accelerator pedal, the engine speed will down to idling, however, the car speed doesn't obviously decelerate; when the car in downhill, the automatic transmission is in the low gear, but cannot make engine braking works.

Causes of malfunction

1. Improper gear adjustment of the shift handle.

2. Improper adjustment of the gear switch.

3. 2 Gear forced brake skid or low gear and reverse gear brake skid.

4. The solenoid valve that controlling engine brake is failure.

5. The valve failure.

6. The automatic transmission failure.

Methods of exclusion

1. Troubleshooting of the electronically controlled automatic transmission.

2. Check if the road test automatic transmission has the slippage.

3. If the gear lever doesn't make engine braking effect in the S position, while Yes in L position, indicating 2nd mandatory brake slip.

4. If the gear lever doesn't make engine braking effect in the L position, but Yes in S position, indicating the low and reverse gear brake slip.

5. Check if the solenoid valve that used to control engine braking is faulty.

a Dismantling of the valve body, and clean all control valves.

b Check each voltage terminals of electronic control units, if normal, then check each sensor voltage.

c Replace and re-test the ECU, if the fault disappears, indicating the electronic control unit damaged.