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Pulse Sensor



What is the pulse sensor?

The pulse sensor is one of the most important sensors in the wash, and is sometimes referred to as the wash’s heartbeat.


The sensor is an inductive proximity sensor, and signals the controller when it detects metal objects (flags) in its vicinity.



For belt conveyor washes the sensor is located at the end of the wash on the driver’s side footwell (see image below).

For chain and roller conveyors the pulse sensor is either located in the conveyor hydraulic tank, or at the end of the wash near the drive sprocket.


How does it work?

The pulse sensor works by detecting nearby metal objects (flags) which rotate with the motion of the conveyor. As the conveyor moves the pulse sensor signals the PLC (programmable logic controller), providing a unit of measurement which is used, in combination with the banner eyes, to determine vehicle length. This heartbeat is used as the unit of measurement and timing for the entire car wash.


We typically use an 8-flag system on our belt conveyor (some systems have 4). These flags are read by the sensor and it is very important that all flags are present and secure.

Prox Collar

8 Flag Proximity Target Collar / P-C2158-2-1516 – (Flags are in Blue)

Helpful information:

The sensor detects the metal flags, it is important to make sure the sensor is adjusted properly, the sensor should be within ¼ of an inch from hitting the flag. Be mindful when adjusting, because if the sensor hits the flag it could damage the sensor.


If you notice that the timing in your wash begins okay but gets worse as a vehicle progresses through your tunnel, you may have lost a flag (possibly broken or wiggled loose).


Another way to check your timing is by looking at your PLC in the MCC Cabinet. If you look at input 09 you should see it flashing while the wash is running. If you notice it flashes regularly and then skips a beat this indicates that the sensor is not reading one of the flags. Remember, this sensor is called the heartbeat of the wash and should be smooth and regular.

Input Card

Input Card

There are different types of sensors listed on our website and it is important that you order the correct one. For anyone with a Tommy controller the correct part number is CCS-T4647600. You can confirm by the color of the wires, as the pulse sensor will include a 3-wire cord with a blue, brown, and black.


Here is a standard Tommy controller wiring diagram for how the pulse sensor is typically wired. Refer to your own wiring manual.

Pulse Switch Diagram


You can bypass the pulse sensor if it were ever to fail by logging into your controller and going to the pulse sensor menu. While in the pulse sensor menu change the “Enter Pulse Sensor Choice” number from a number “1” to a number “3”. This will put you into Stand-by Pulse. If, after changing this setting, your timing still isn’t correct you may need to adjust the “Stand-by Pulse Rate”. Going bigger with the number will slow everything in the tunnel down and going smaller will speed everything in the tunnel up.


Make sure that every time you change your belt speed you press the “Set Pulse” button to keep the most accurate “Stand-by Pulse Rate”.


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