Car reverse light switch

How to detect the reverse light switch failure

To inspect the part operability, you need a multimeter set to a continuity check mode. The gauge contacts are connected to the corresponding terminals of the tested part. For greater measurements accuracy and to prevent short-circuit, it is advisable to connect the multimeter probes to the sensor contacts through two insulated wires. Then, shift transmission to the reverse gear. If you hear no sound signal, then the switch circuit is broken. Constant sounding of the signal, with reverse gear both on and off, indicates a short circuit inside the component. To check the sensor removed from the car you have to act on its plunger by hand.

If you do not have a multimeter, you can use a test lamp. For this, connect one of its contacts to the battery, and the second one to one of the switch terminals. The second switch terminal is connected to the battery. Absence of light with the activated plunger indicates a sensor fault. The continuous lamp light regardless of the plunger position also indicates the contacts closure.

You may identify that the reverse light switch has to be inspected by the following signs:

• when the reverse gear is engaged, the lights do not turn on;
• reverse lights stay constantly on;
• when you move back, the lights flicker;
• oil leaks out from under the sensor.

Causes of the reverse light switch failure

Many switch faults are caused by its housing disintegrity, as a consequence of which moisture and dirt get inside the component. Eventually this leads to contacts oxidation and electrical circuit opening. Besides, oil getting into the part from the transmission prevents the electric current from free flow, since oil is a non-conductor.

Sometimes the reverse light limit switch malfunction is caused by the movable contact abrasion, due to which the circuit is not closed when the plunger is pushed. In case of the return spring wear, the contacts are constantly closed and the reverse lights do not turn off.

Incorrectly adjusted plunger on some sensors can cause the membrane to rupture. In this case, the switch needs replacement. If the plunger length is not sufficient to activate it, it is possible to solve the problem by adjusting it.

The oil leakage from under the sensor is usually caused by applying excessive force when trying to screw it in, or the part’s poor quality.

Replacement of the reverse light switch

The part is not repairable. If the problem in its performance cannot be eliminated by cleaning the contacts or adjusting the plunger, you need to install a new switch. If you replace the part on your own, perform the following procedure:

1. Mount the car on a pit or a ramp.
2. Apply the parking brake.
3. Dismantle the crankcase cover.
4. Disconnect the wire connector from the switch.
5. Put a container under the gearbox and unscrew the component.
6. Acting quickly to prevent oil loss, pull the switch out from the mounting seat and install a new one in its place.
7. Refill the lubricant in the transmission to the necessary level.