Technical start&stop issue

[Giof]

Hi, I bought a Fiat 500L 1.6 JTD 105 HP year 2014, the start&stop system never worked, the battery have been checked and it is ok. I noticed that if the car accidentally shut off ( due drivers error, a wrong gear on at the start for example) the car restart automatically as the start&stop was working ok. I think the issue is in the part that have to stop the engine. anyone of you had this issue? Many thanks, Giovanni

 

[Rototype]

Hi Giof,

If your car was at the dealer for any length of time it's possible (even if the battey is OK) that the charge might be too low for the system to work on Start/Stop. Mine was nearing flat when I picked it up (OK, OK, it needed a jump start, but that was due to an issue with a faulty Bluetooth module draining the battery) and took nearly a month and a few good long runs before Start/Stop began to work (frightenned the life out of me when it finally did work as I wasn't expecting it...), and it was still fussy about battery level 2 years later. Surprisingly a week before I picked it up when I took it for a test drive the car auto restarted after I stalled it trying to get it out of the dealers lot. I think the auto restart often works when Stop/Start doesn't.

 

[The Panda Nut]

Probably IS battery age as dealers just seem not to be aware of battery things. 10 years old battery still working is good. Anticipate the bbattery life ifit getsvery cold andbe prepared to change it.

 

[PuntoHowTo]

The answer to “stop start not working” on any fiat is almost always the battery needs replacing.

Fiat stop start systems are fickle and only happy with a new or nearly new battery. Anything that is a few years old or more while still being a perfectly god battery and working on any other car will fail on a fiat to operate stop start.

The only other possibility is the battery sensor module fitted to the battery terminal, sometimes the wires on the connector can break or the module fail but, while wires breaking isn’t out of the realm of possibility, I don’t think I have ever seen a failed battery condition module on this forum confirmed…. Because it’s usually the battery needs changing

On a 2014 car it might even still have the original battery

 

[Tropicalmike]

My start stop wasn't working on my 64 plate twin air and I put it down to an older battery but 3 weeks ago it started working . It worked for a week and I quite liked it when driving in town . But it has stopped working again despite the car having a couple of 40 mile journeys. So I thought I would try and get it working. This is what I have tried so far

• I checked the battery with a tester and it showed 100% state or health ( SOH) and 98% state of charge (SOC) and CCA correct too. It has worked for this period so I think the battery is good
• I disconnected and inspected and cleaned all battery terminals , they were all good, no corrosion
• I have had a good read on FIAT e-learn website and hooked up my multiECUscan. (MES) The e-learn gives a good description of what inputs effect the Start-Stop. IE . Clutch pedal released, gear in neutral, disable push button and Brake servo pressure switch and battery monitor sensor , The clutch. gear neutral and servo pressure switches all worked but there is no parameter for the battery monitor in MES. The parameter for start stop disable did not change when I pushed or held the button. However, the yellow disable light shows in the instrument cluster .
• Unfortunately , the e-learn does not give any further info on the logic that is used to permit or deny the start stop to operate . EG, engine cold , demand from AC . heated rear window etc you would think might block start-stop.
• I checked the fuse that feeds the battery sensor F87 I think it was and it was OK.
• I put my multimeter on the wiring of the monitor and the +ve 12 V was present and there was a resistance between the 2 pins on the monitor. I also checked the battery voltage when charging with engine running, 14v present .
• I then unplugged the Intelligent battery sensor (IBS) . This generated a fault code U1411-87 in MES and the yellow fault light triangle on instrument panel , This not surprisingly is the fault for loss of signal from intelligent battery sensor . I plugged it back in and cleared the fault , The wiring diagram shows the other wire from the IBS goes into the body computer , as does the other switches already mentioned . The e-learn description says the info from the body ECU communicates with the engine ECU via the Canbus where the start-stop is controlled
• I checked the resistance of the main -ve cable to the chassis and engine. Less than 0.2 ohms ( about as accurate as my meter can do )

Any one got any other ideas or suggestions on things to check ? I have access to another twin air so I will try and compare/swap the IBS units to eliminate that .

thanks in advance