half differential short cuirciting ring sensor (HDK sensor)

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Posts: 3
Joined: Fri Jul 06, 2007 10:12 am
Location: Meath,Ireland

half differential short cuirciting ring sensor (HDK sensor)

Post by Amechs » Tue Aug 07, 2007 9:16 am

I am trying to understand this sensor and have captured a few waveforms.
The sensor is supplied on two wires by a 10kHz,opposite phase AC signal and the third wire is the output signal.

On my sensor the output voltage is a steady 3.5v under all conditions.
Does anyone know how this signal is interpreted by the ECU and how I can detect a faulty signal or sensor?

This sensor is common in Bosch EDC DI injector pumps to measure the position of the fuel quantity adjuster(collar).Pumps fitted to Renault,Volvo,VW plus others.

Any help will be appreciated.



Post by Guest » Tue Aug 07, 2007 8:37 pm

i think this is right, one ac signal is used as a reference by the ecu and the other ac signal should change in relation to the control collar on the plunger. hope this helps.


Post by Guest » Thu Sep 20, 2007 10:05 am

Is the 3.5v actually from the ECU rather than the pump?

Do the AC signals have a 'zero' or 'crossover' point at 3.5v?

If so then one of the signals could be from the ECU and the other from the pump.

What is the relationship between these signals and the quantity solenoid signal.

I'm currently researching this ECU & pump and I am very interested in any info you would like to share.


Posts: 3
Joined: Fri Jul 06, 2007 10:12 am
Location: Meath,Ireland

HDK sensor

Post by Amechs » Thu Sep 20, 2007 1:17 pm

Hello Guy,
Thanks for your reply.
Having done further tests my original post is misleading.

The third wire is a common ground between the reference and signal wires
The reference voltage is aprox 1.5 to 3.5 volts AC 10KHz.
The signal voltage is aprox 1.5 to 3.5 volts AC 10KHz when the sensor is at the end of its travel i.e idle

When the sensor is moved to the other end of its travel the signal voltage goes from 0.5 to 4.5 volts AC 10KHz.

I have attached a waveform I captured using Picoscope 6 where I moved the sensor manually to the end of its travel i.e. max fuel injected.
This was achieved by removing the top from the pump.

Output signals amplitude increases as sensor moves while reference signal remains constant.
Third wire remains constant at midpoint between two reference signals.

This pump is fitted to Volvo S40 1.9td 4192T2 engine made by Renault

On ignition on actautor moves to idle position and is held if no start until ECU moves it to STOP after aprox 30 secs.
Afterwards,actuater can be moved manually from 0 to 100%, output signal changes accordingly.

On ignition off,actuator moves to aprox 50% then returns to STOP and bounces once or twice.

I have this pump disassembled so if you want some photos I can email them to you or if you have any more questions.
HDK sensor max movement.gif
This shows relationship between both signals at MAX position.
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