If you are a driving or car enthusiast who appreciates extreme performance, you most likely prefer manual transmissions. And you must have heard of or even done reverse lockout wiring for the system.
Reverse lockout is a safety feature that prevents you from accidentally engaging reverse gear when shifting if the car is moving forward past a specific speed.
Let’s look at how this feature works and its wiring process.
Table of Contents
- How the Reverse Lockout Feature Works
- Reverse Lockout Wiring
- How the ECU Controls the Reverse Lockout Mechanism
- Reverse Lockout Wiring Steps
- Wrap Up
How the Reverse Lockout Feature Works
If you accidentally engage the reverse gear, not only will you damage the transmission, but you can also get an accident from rear-end collisions from multiple cars.
The reverse lockout feature uses a physical barrier or electronic sensor to prevent this situation.
You can only deactivate this sensor or barrier by performing a specific action to engage the reverse gear.
Car manufacturers set these actions to ensure the driver is aware when switching to reverse so that it is not by accident.
These actions usually include either of the following.
Depressing the Clutch Pedal
All manual vehicles have a clutch pedal. But the reverse lockout clutch-pedal deactivation requires you to press the clutch pedal fully before shifting to reverse.
When switching between the front drive gears, you don’t have to depress the pedal to the floor. But this action is necessary to engage the reverse.
Accelerator, brake, and clutch pedals
Ring Lifting or Collar Movement
Depending on the car’s make or model, you can find a transmission ring or collar that should be moved or lifted in a specific manner to engage the reverse gear.
Unlike the fully clutch pedal depression above, this action includes an additional step that eliminates accidental reverse gear engagement.
Pushing a Lever or Button
This action also includes an additional step that makes the reverse lockout more effective.
Manual cars with this feature have a separate button or lever that you must push or pull when shifting to reverse for it to engage.
A manual gear stick with a few buttons under it
Reverse Lockout Wiring
Wiring this system involves handling the electrical components and connections, and here’s a close-up look at what you need to set up.
Reverse Lockout Switch
Most manual vehicles feature reverse lockout switches near the gear selector, which link to the reverse lockout mechanism.
Pressing this switch sends an electrical signal to the vehicle’s computer (ECU or PCM), informing it that you want to engage the reverse gear.
This ECU then determines if it is safe to deactivate the locking feature, allowing you to push the gear stick into the reverse position.
Clutch Pedal Switch
The clutch pedal switch operates similarly to the reverse lockout switch, but it sits on the clutch pedal assembly or the floor behind this pedal.
So, when you depress this pedal fully, it activates the switch, sending a signal to the ECU informing it to assess whether it is safe to engage the reverse gear. The computer responds by deactivating the locking feature or keeping it locked.
ECU (Control Unit)
The ECU controls various electronics around the vehicle using data input from sensors. Modern vehicles usually involve this control module in operating the reverse lockout feature.
A vehicle’s ECU
In this case, the sensors are the reverse lockout or clutch pedal switches. Once it receives the data, the ECU determines if it is safe to engage the reverse gear.
Dashboard Indicator Lights
Some manual transmission vehicles have dashboard indicator lights that illuminate to show the status of the reverse lockout feature.
When you press the pedal or switch, and the ECU deactivates the system, the light can go off, change color, or switch to another off-light to indicate the system is off.
This setup makes it easy to inform you when your vehicle can engage the reverse gear.
Wiring Harness
Wiring harnesses connect these components to transmit electrical power and sensor data signals to the respective parts.
A car wire harness with adapters and connectors
How the ECU Controls the Reverse Lockout Mechanism
The ECU is a computer or control unit, meaning it does not handle the physical blocking of the reverse gear slot. Instead, it controls actuators to perform specific functions to get the desired results.
In the reverse lockout mechanism, the ECU controls a reverse solenoid to mechanically block the reverse gear slot until you press the switch, lift a ring, move a collar, etc.
Let’s look at how this solenoid works.
Listening for the Activation Signal
Once you drive forward past a certain preset vehicle speed, the ECU engages the reverse lockout mechanism, blocking the reverse gear slot.
So, as you drive, the ECU continuously listens for feedback from the sensors to act accordingly. If you press the switch, the ECU receives the activation signal and assesses whether it is safe to switch to reverse.
If you’re below the set speed limit for blocking reverse switching, the ECU uses the reverse lockout signal wire to activate the reverse lockout solenoid.
A solenoid switch
Plunger Movement
The ECU’s activation signal to the solenoid is an electric current that energizes its coil. This action creates a magnetic field that pushes the plunger outward.
Reverse Gear Unblocking
The plunger connects to the physical blocking mechanism, usually a cable or mechanical linkage that hooks onto the gear stick. When it moves, it unblocks the reverse gear engagement, enabling you to insert the stick into that slot.
If your vehicle has a dashboard indicator light for this feature, the ECU will send it a signal to turn it on. Usually, it sends the signal after energizing the solenoid and moving the plunger out successfully.
Reverse Lockout Wiring Steps
We’ve listed all the electrical components making up this reverse lockout module. So, wiring involves connecting these parts, from the switch to the ECU, dashboard lights, and solenoid.
First, gather these items.
- Wiring harness for the respective vehicle
- Car wiring diagram or service manual
- Reverse lockout/clutch pedal switch
- Tools
Step 1: Identify the Electrical Connections
Check the vehicle’s wiring diagram or service manual to determine the required electrical wires and tools. Wrenches, pliers, and screwdrivers might be necessary, but consult the vehicle’s document to determine the specifics.
Step 2: Install the Switch
Whether you use a reverse lockout switch near the gear selector or a clutch pedal switch, install the device and wire it accordingly.
You might have to connect some to an ignition-switched power source and others to the chassis ground.
But all must have a reverse wire link to the ECU to transmit the activation signal. Check the specifics of the wiring in the user manual or the vehicle’s wiring diagram.
Step 3: Wire the Indicator Lights
Connect the dashboard indicator lights (if present) to the ECU, and ensure they have well-installed ground and power wire connections.
Step 4: Connect the ECU to the Solenoid
Next, link the control unit to the solenoid, ensuring solid power & ground wire connections and firm pin connectors.
Multicolored ECU wiring
Step 5: Test the System
Test the wiring to check if the ECU locks the reverse gear from engaging and if the buttons or switches disengage the system accordingly. Also, check if the reverse light works.
Step 6: Secure the Wires
Secure the wires to the vehicle using zip ties, grommets, cable straps, etc. That’s it!
Wrap Up
Wiring the reverse lockout feature is relatively easy once you identify the components that make up the system.
These components can vary depending on the car’s make & model and age. Older cars didn’t have electronic controllers, meaning the lockout connection from the switch might be direct.
So, always consult the vehicle’s wiring diagram or manual.
If you are interested in vehicle transmission systems, check out this auto transmission overdrive article to learn more about the feature.
