Hallo together!

I own a Fiat Croma 2.4 Multijet 20V DPF automatic year 2005. This can't be switched from automatic to manual mode.
In automatic mode, the transmission switches error-free. When you restart of the engine or when the ignition is switched on, the manual mode can be select and switches the gears 1 to 3, up and down. In the 3rd gear, the gearbox stops switching higher and gives a beep. When you drive in manual mode the mode changes automatically from manual to auto.
The error P1720 occurs, which can be erased but causes no further restrictions. If the motor is switched off, the vehicle confirms this with 14 tones, why ever. No more errors exist, only a window regulator is broken. Until now, no one could help me with concrete proposals.
I would appreciate support and useful suggestions for troubleshooting!

KR

PBeierle said:

Hallo together!

I own a Fiat Croma 2.4 Multijet 20V DPF automatic year 2005. This can't be switched from automatic to manual mode.
In automatic mode, the transmission switches error-free. When you restart of the engine or when the ignition is switched on, the manual mode can be select and switches the gears 1 to 3, up and down. In the 3rd gear, the gearbox stops switching higher and gives a beep. When you drive in manual mode the mode changes automatically from manual to auto.
The error P1720 occurs, which can be erased but causes no further restrictions. If the motor is switched off, the vehicle confirms this with 14 tones, why ever. No more errors exist, only a window regulator is broken. Until now, no one could help me with concrete proposals.
I would appreciate support and useful suggestions for troubleshooting!

KR

Click to expand...

hi,

P1720 - Vehicle Speed (Meter) Circuit Malfunction


presumably your vehicle has 2 x speed inputs ;

a wheel speed input - from the ABS rotors,

and a gearbox speed input - from the speedometer drive

initially check that both of these are present.

Sorry to sound like a broken record & I'm not on commission, but you need Multiecuscan www.multiecuscan.net a USB ELM 327 interface and a laptop. With this you can read the fault codes properly, read and graph parameters such as speed and do some proper fault finding.

Robert G8RPI.

Thanks! I've got EcuScan and try to find out which signal is missing. I've just studdied the eLearn CD and think i'll try the speed test first.

The transmission has also got its own speed sensor running of the output shaft to tell the transmission ecu of output speed.

PBeierle said:

Thanks! I've got EcuScan and try to find out which signal is missing. I've just studdied the eLearn CD and think i'll try the speed test first.

Click to expand...

The transmission has also got its own speed sensor running of the output shaft to tell the transmission ecu of output speed.

thanks buster

Not an easy job to change though.Oil out of box,front pan off,valve block off and its visable then.A common fault with these sensors is shards of metal sticking to them through being magnetised.Maybe an oil change would cure it.

I checked wih EcuScan the speed for each wheel in the ABS when driving. The speed is nearly the same shown by the speedometer. When i check the speed in the gearbox, the shown speed is always factor 10 less then the speed i am driving. For example: driving 40,0 km/h, shown in EcuScan 4,0 km/h. Where can i find the Speed sensor in/at the gearbox?

PBeierle said:

I checked wih EcuScan the speed for each wheel in the ABS when driving. The speed is nearly the same shown by the speedometer. When i check the speed in the gearbox, the shown speed is always factor 10 less then the speed i am driving. For example: driving 40,0 km/h, shown in EcuScan 4,0 km/h. Where can i find the Speed sensor in/at the gearbox?

Click to expand...

sounds promising..

:idea:I'd maybe try a relearn .., as it's CONSTANTLY reading wrongly.

otherwise buster.. do you know about access..??

If your using FES or MES or what ever we call it.Look in assin and monitoring menu.I wouldnt just change it for the sake of it.Its a swine getting the pan off due to the torx headed bolts,and two at the bottom you cant see.The valve block comes off easy and its behind it.The worst bit is getting the pan back on, because of no gasket it uses sealer instead.When you lower the pan back in place it fowls some components and pushes the sealant off.Took me two attempts.

buster said:

If your using FES or MES or what ever we call it.Look in assin and monitoring menu.I wouldnt just change it for the sake of it.Its a swine getting the pan off due to the torx headed bolts,and two at the bottom you cant see.The valve block comes off easy and its behind it.The worst bit is getting the pan back on, because of no gasket it uses sealer instead.When you lower the pan back in place it fowls some components and pushes the sealant off.Took me two attempts.

Click to expand...

I checked the power supply, ok.
Today I was again in a Fiat garage read the errorcodes, the result:

Error P1720: gear selector housing (NSC); Invalid signal; Available Possible causes: position selector gearbox lever defect, gear change control is faulty, defect harness, control unit defective (Examiner Release: 109.16.1).
The garage told me to try first to replace the gearbox lever and look for a propper harness.
Here a part of my EcuScan Log, some parts were cut to reduce the post.


ECU ISO Code: C4 85 89 04 AB
08.08.2016 18:04:30
CONNECTED TO:
Fiat Croma '05 2.4 MultiJet 20V
AISIN AF40-6 Automatic Gearbox
--------------------------------------------------------------
ISO-Code: C4 85 89 04 AB
FIAT-Zeichnngsnummer: 55196490
Hardware-Nummer: 89503TFA220
Hardware-Version: 00
Software-Nummer: 9938104653
Software-Version: 4001
Zulassungsnummer:
Datum der Programmierung: 07/11/2005
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 5,0 km/h
Gang eingeschaltet: Vierter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 5,0 km/h
Gang eingeschaltet: Vierter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 4,4 km/h
Gang eingeschaltet: Dritter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 4,5 km/h
Gang eingeschaltet: Dritter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 4,5 km/h
Gang eingeschaltet: Dritter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 4,5 km/h
Gang eingeschaltet: Dritter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 4,5 km/h
Gang eingeschaltet: Dritter
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 0,0 km/h
Gang eingeschaltet: P/N
Eingestelltes programm: Eco/City
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 0,0 km/h
Gang eingeschaltet: P/N
Eingestelltes programm: Eco/City
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 0,0 km/h
Gang eingeschaltet: P/N
LESE PARAMETER:
Fahrzeuggeschwindigkeit: 0,0 km/h
Gang eingeschaltet: P/N
LESE FEHLER CODES:
1: P1720 - Gangwähler - Gehäuse (von NSC)
FEHLER DETAILS:
Batteriespannung: 13,6 V
Gaspedalweg: 0 %
Motordrehzahl: 775 rpm
Drehzahl Getriebeausgang: 0 rpm
Gang eingeschaltet: Erster
Temperatur des Getriebeöls: 43 °C
No help available
Der Grund für diesen Fehler ist, dass die ECU ein ungültiges Signal vom Sensor übermittelt bekommen hat. Der Fehler ist aktuell vorhanden und aktiv. Beheben sie den Fehler und prüfen sie neu bzw. löschen sie den Fehler. Kontrollleuchte NICHT aktiv bei diesem Fehler.
gespeicherte Fehler gelöscht...
LESE FEHLER CODES:
Keine Fehler vorhanden

Gear selector node.sounds like its not on can,lost its data link.just have a look on the engine control unit to see what faults are on there.Its quite a simple system.Basically when you operate the auto side of the box,it pulls cables that operate a shaft that passes through the transmission control unit.The control unit then electrically controls the valve block because it knows the position.
When the transmission is used in manual the transmission control unit directly operates the valve block.It requires to know engine speed,this is transmitted down the data link between engine and gearbox.Just check the two engine speeds,crank and cam.

As been said,its road speed thats missing.Monitor the parametres on every control unit whilst road testing.

I tried to get this part here in Germany at several Fiat dealers, but without success.
They all tell me, that there is no partnumber in der comuptersystem and so not possible to get one. Can you help please me with a partnumber. I only can get the crankshaftsensor.

PBeierle said:

I tried to get this part here in Germany at several Fiat dealers, but without success.
They all tell me, that there is no partnumber in der comuptersystem and so not possible to get one. Can you help please me with a partnumber. I only can get the crankshaftsensor.

Click to expand...

buster may know

Or maybe use Google to try and find a supplier of the part.or sensor

Charlie

Gonig to have a look now.

J pat.
[email protected]
www.jpat.co.uk
+44 (0)1934 852772

Part no

255436A (input speed)

255438A (output speed)

Pity your in germany,you could have gladly used our workshop and i,d gladly help you.