What Is a KITAS II+ Tachograph Sender?

A KITAS II+ is the speed sender for a digital tachograph. It mounts on the gearbox output, reads vehicle speed and distance, and sends that signal to the tachograph head over an encrypted line. The encryption is the point: it pairs to the tachograph so the recorded speed and distance cannot be tampered with. On a truck or bus running a digital tachograph, the KITAS is the part that feeds it.

This matters because a tachograph sender and an ordinary speed pulse generator look similar and bolt into similar places, but they are not the same part and do not swap.

Where it fits

The KITAS II+ threads into the gearbox output and reads the rotating shaft, the same position a standard sender uses. From there it runs to the tachograph head in the cab. Our KITAS II+ unit is a 19.8 mm probe with a 4-pin round terminal, sized for that gearbox port.

Because it drives a legally recorded instrument, the sender is paired to the specific tachograph during fitment and calibration. You cannot move a paired sender to another vehicle and expect it to work; it has to be set up against that head.

What it does

Three jobs:

1. Reads the gearbox output speed.
2. Converts it to a pulse signal proportional to road speed.
3. Sends that signal to the tachograph over an encrypted, authenticated line.

The encryption and pairing are what separate a tachograph sender from a plain pulse generator. A standard sender outputs a raw pulse that anything can read; the KITAS outputs a signed signal that only its paired tachograph accepts. That is what makes the recorded data trustworthy.

How it differs from a standard speed pulse generator

A standard VDO speed pulse generator (for example, a 4-pin M22 inductive unit) feeds speedometers, fleet trackers, rev limiters and cruise control. Its output is a plain pulse. It is not paired and not encrypted, so it is easy to fit and easy to replace.

A KITAS II+ does the same physical job, reading shaft speed, but adds the encrypted, paired output a digital tachograph needs. Two consequences follow:

• You cannot replace a tachograph sender with a standard pulse generator. The tachograph will reject an unsigned signal.
• A KITAS fitment includes pairing and calibration against the tachograph head, which a plain pulse generator does not.

If the part is feeding a digital tachograph, it has to be a KITAS. If it is feeding anything else (a speedo, a tracker, a limiter), a standard pulse generator is the right and cheaper part.

Identify the right part

Confirm three things before ordering:

• The tachograph type the sender pairs to.
• The gearbox port: probe diameter and thread (our KITAS II+ is a 19.8 mm probe).
• The connector: pin count and terminal type (4-pin round terminal here).

If you are replacing an existing sender, the part number on the old unit is the fastest route to the correct replacement.

How to order or request a quote

Tachograph senders are paired to the head, so tell us the tachograph and the vehicle when you order, and we will confirm the right KITAS II+ unit, stock and lead time. Calibration after fitment is required and is best booked with a tachograph centre.

See the Sensors & Senders range for KITAS senders and standard pulse generators. To get pricing, request a quote with the vehicle and tachograph details.