Speedo Malfunction

[ReganAndCarter]

No, not a problem with my swimming attire, it's my 2004 Fiat Scudo 2.0 HDi van. On my way to Portsmouth on Monday to get the ferry across The Channel, and my van's speedometer went all French on me and suddenly refused to work any more. Even worse, the odometer and trip meter decided to come out in sympathy.

The speedo is traditional needle type - it now just sits at zero without attempting to move. The odo and trip meter share the same backlit LED type display. They both still display the mileage correct at the time of the malfunction happening - ie. they are frozen and don't register any additional miles since the malfunction.

As three things have suddenly stopped working, does this point to the speedo being faulty, or is it likely that whatever sends the speed and mileage info to them is at fault. How can I test?

Any pointers (pun intended) as to what wrong with the speedo, etc greatly appreciated.

 

[robinbanks]

Quick read around seems to indicate they're driven off a sensor on the gearbox, a cheap part to buy but no idea what access to it is like!

 

[Koolpc]

Scrap the van! Lol

 

[Mottie]

Dunno about Scudos but on some cars, the electronic speedo drive fits where the cable speedo drive fits and is held in by a single bolt or a roll pin. Pretty easy to change - usually!

 

[Burnerman]

The sensor is on the differential nearside, if I recall.....the plug is prone to water ingress but the sensor is easy enough to change.
(Citroen gearbox).
John

 

[ReganAndCarter]

Thanks to all who replied. So we're betting on the sensor/sender down on gearbox/diff. Will have to have a root around to locate. Also have a look at getting part - the Fiat 'Eper' website is a good place to start as it has all the exploded parts diagram same as dealers, complete with part nos.

Next question - if I renew the sensor, will mileage be lost or will it still be showing as correct?

 

[Mottie]

Nest question - if I renew the sensor, will mileage be lost or will it still be showing as correct?

If it’s not working, nothing will be recorded until it’s working again.

 

[ReganAndCarter]

OK, thanks Mottie. One other thing, I noticed at the same time the speedo stopped, some slight hesitance/jerkiness in lower gears at lower speeds. Almost like slight fuel starvation. This was never there before and drove perfectly. Would I be right in thinking that the faulty speed/rpm sensor also sends info to the ECU that adjusts fueling, etc and is causing this slight lumpiness? It's not noticeable all the time and not there at motorway speeds.

 

[Burnerman]

The recorded mileage won't be affected.
There is a possibility that this sensor also functions as a 'motion sensor' - so if your luck is in.....!
John

 

[ReganAndCarter]

The sensor is on the differential nearside, if I recall.....the plug is prone to water ingress but the sensor is easy enough to change.
(Citroen gearbox).
John

Poss worth a try unplugging and getting some electrical contact cleaner on the plug and socket first. Part isn't too expensive though, so will change if that doesn't work. A Febi one is just over £30.

One thing some Googling threw up is the plug may be in an awkward position on diff and one or two people suggested a ramp is necessary. Will have a poke around when I get back. Thanks to all for info.

 

[ReganAndCarter]

One thing some Googling threw up is the plug may be in an awkward position on diff and one or two people suggested a ramp is necessary. Will have a poke around when I get back. Thanks to all for info.

When I get back I may get my ramps out and see if I can get access to the sensor that way. May be worrying unnecessarily about access. If it's a real mare I might bite the bullet and go to one of those hire a 2 post lift by the hour places. There's one in Cheltenham, not too far from Bristol. I want to inspect the wiring to sensor as well and get some contact cleaner in there.

SCA Rent-A-Ramp is Cheltenham’s only DIY vehicle repair facility available for hire.

SCA Rent-A-Ramp is Cheltenham’s only DIY vehicle repair facility available for hire and is conveniently located close to Bristol, Gloucester and Tewkesbury.

www.rent-a-ramp-cheltenham.co.uk

When I said I notice slight hesitancy/jerkyness in lower gears at lower speeds that has probably been caused by the sensor failure no longer sending info to the ECU. Have also noticed that the MPG is down a little too. Wouldn't normally be a problem as I don't do many miles, but typical it all started as I was starting a rare very long journey spanning several countries and hundreds of miles. C'est la vie!

 

[Mottie]

Have also noticed that the MPG is down a little too

How can you tell if the odometer is not working?

When I said I notice slight hesitancy/jerkyness in lower gears at lower speeds that has probably been caused by the sensor failure no longer sending info to the ECU.

My son had a Fiesta and the electronic speedo unit gave him idling problems when it stopped working. Engine would race at idle. When it was replaced, the idle speed returned to normal.

 

[ReganAndCarter]

How can you tell if the odometer is not working?

My son had a Fiesta and the electronic speedo unit gave him idling problems when it stopped working. Engine would race at idle. When it was replaced, the idle speed returned to normal.

Can't quantify the drop in MPG, but just feel that the needle on gauge goes down a bit quicker. Maybe it's just me. Only marginal, not ruinous.

My idling is ok, just a little hesitant and less smooth when moving up lower gears accelerating. At 120 KPH on the autoroute don't notice any difference.