406 TPS wiring

[barwood]

I wonder if anyone out there can help me, I live in France and my neighbour has a 1999 406 2.0 HDI estate which he uses when he comes over to France but on his last visit the car started no problem but idles at about 1200 rpm and has no throttle operation,I have a 2.0 HDI citroen Synergie which uses the same TPS so I put his on my car and it works fine. The only difference is on the plug all 4 pins on the 406 are giving a voltage between 10 & 12 volts whereas the Citroen has one going to earth. I looked at a wiring diagram and it shows the 4 wires going straight to the ECU, I don't know the wiring inside the ECU so I don't know if this is correct.
Any help gratefully received.

[Doggy]

Hi & welcome aboard

I don't have access to diagrams for an early HDi at the moment , but will try to check for you this evening, (unless someone beats me to it).
FWIW, later 406's with I guess the RHY engine definitely have all 4 wires going to the ecu.

Guessing you're a Brit, but possibly fluent in French?
The French 406 forum may also be able to assist:
https://www.passion-406.com/

[barwood]

Thanks for the welcome Doggy,
It's got the RHZ engine the same as in my Evasion/Synergie that's why I tried the TPS on my car to check it worked and then I thought o check the pins and one of mine on the Citroen goes to earth and the Pugs doesn't

Yes I'm a Brit but to say I'm fluent in French would be pushing it.

[Doggy]

Here we go....



B138 is the TPS, as you can see all wires go to the ecu. 1331A/B/C is shared with B180, (Fuel rail pressure sensor) and B31, (Fuel temperature sensor).

Might you be able to monitor the voltage on 1378 / pin 2 with respect to pins 1 & 4? That should tell you if it has a supply and the output changes with pedal position.

Failing that, you really need access to a Lexia 3 / Peugeot Planet 2000 system.

Whereabouts in France are you, if you don't mind me asking? My bro's renovating a cottage in the Creuse (23) and coincidentally has a dead 406 parked there that I'm going to try to resuscitate next month.viewtopic.php?f=1&t=24551

[barwood]

Thanks again for taking the time Doggy (apt name for us we run a boarding kennels & cattery in Brittany (56).Your brother is about 6 hours from us.

I've got a Lexia/PP2000 and have a picture of the result but I can't work out how to upload it !!!!
Do you know if one of the pins earths through the ECU? On my car one of the pins goes to earth.

[Doggy]

We normally use Photobucket or similar to host the picture, then post the link as in my one above with the diagram.
(If you try to edit my previous post you should see how it's done).

Sorry, I don't know which wires, if any, connect to earth via the ecu and would advise against trying to check unless you really know what you're doing.

On PP2000, you should be able to view the throttle position in 'Driving Parameters' with the engine stopped / ignition on.
Should be 0% without pressing the pedal and 99% at full throttle.

[barwood]

http://s733.photobucket.com/user/barwoo ... s.jpg.html

Does this work??

[frog]

http://s733.photobucket.com/user/barwoo ... s.jpg.html

Does this work??

Looking at the massive amount of "Short circuit to positive" faults, i would think of a problem with an earth connector or earth strap.

The electric leads from the ECU to the sensors often have so-called "pull-up" resistor internally in the ECU, which is why it reads the maximum values whenever the earth connection is gone.

Here is a diagram of how a sensor is typically connected:

If the earth wire/strap (E1 at the bottom) is bad or gone, the ECU-internal pull-up resistor will make that the voltage on the sensor wire (THW) goes up to 5 Volt. The ECU will then (falsely) report that there is a short between the sensor and the positive.

Maybe the Citroën version TPS sensor has an internal connection to earth, which is why connecting it solves your problem (temporarily).