Hi all,
Car: Fiat Stilo 1.9 JTD 115 "02".

The problem is with starting, when trying there appears to be a massive current drain on the battery, cranks 2 times before lights go off and no more cranking.

First thought was battery as we all know how Stilo's love a strong battery. So I went and bought a heavy duty one and fitted.
Result was the same problem.

Next thought was starter motor, so got it off (easier said than done), pulled it apart and found worn brushes (thought great found the problem) see attached photo of old. So ordered a set of new brushes complete with holder. They arrived, were fitted. Tested the starter motor on the bench and it span well although obviously this was with no load so not a true test but still reassuring. Then re-attached the starter motor to the stilo.
Result still the same problem although not all bad as the brushes clearly needed changing.

Next thought was to use FES and check error codes:
U1706: engine> ABS data line no signal
U1600: Immobilizer: key faulty no signal
P0190: Diesel pressure sensor signal high
U1700: CAN: Body computer conn. fault (1) no signal

I was able to clear all of these with FES, then tried to start the car again...same problem. So checked the error codes again, but they had not come back. Initial thoughts on this are that they were stored from when the battery voltage was low as I'm sure you all know the how many strange things happen when its low.

So the reason why I think it is now an electrical short somewhere is that when measuring the cranking voltage accross the battery it drops from 12.8V to 7V, I would only expect it to drop to maybe 10/9V? Would someone please be able to measure their cranking voltage for comparison? (voltmeter across terminals set to 20V and someone start the car while you watch what the voltage drops down to)

My next trial is going to dissconect the supply and control voltage lines to the starter motor and attach jump leads, then use a battery to spin it, this will hopefully rule out the starter motor. (possible shorted wind although would have expected it not to spin on bench if thats the case).

Any thoughts would be appreciated as I'm a student and can't afford to keep spending money on it even if I do love it.

Thank

odd. starting a car requires a huge amount of power at cranking, so, is it possible you have a break somewhere? I know its simple stuff but id check the clamps, cables and earths. Its just ive had issues like this before with other cars, and often its been cables or clamps etc. Just a thought, but it seems you are on the right track in terms of diagnostics-but for me, if the lights are going out, that suggests either a break somewhere or a short/poor earth connection...best of luck though i hope you get it sorted easy enough.

With the cranking voltage dropping that low, I wouldn't rule out the possibility of a seized engine. (timing belt perhaps) Try turning it over by hand with the ignition switched off.
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Hi all,
Sorry I didn't get back to you earlier, have been in the garage since my last post.

Thanks Clivvy, good suggestion but I have already checked all cables and clamps...wish it was that simple this time.

Hi Davren, yes I had checked the engine turned free although it was rather hard to turn it even with a big T-bar again it was another possibility thanks.

Thanks cris1117, I have already checked the earth although I have not tried a tow start yet so can't say if it will start.

To update on what I have done and what I believe is the problem:

Using a spare battery and spare positive and earth leads with terminals:
Disconnected the main power supply at the starter and the jumper going to the alternator, bolted these together and covered in insulation. I left the control positive still attached to the starter motor (signal to switch the solenoid). I connected the spare positive lead to the new battery and the other end to the main supply on the starter. Then attached the earth lead to the block. This test was to check if it was the something else draining the current or the starter.
Now was time to try again, still the same problem only this time the voltage on the cars battery only dropped to 11.98V, this meant that the drain was confirmed to be from the starter motor.

Removed the starter yet again and opened it up, this time used a multimeter to check the continuity around commutator and from that to beyond the insulation to check that there was no short.
Put it all back together and checked on the bench with jump leads that it was working and yet again it was, which confused me.
So put this back on the car, getting to be like and F1 pit stop this.

I had a quick stop for food and phoned a few friends to see what they thought and most said it sounded like it was still the starter motor, possibly the bearing since I can't check it under load.

I went back to looking and think I have found the answer!!!!
............It is (hopefully if I am right) a seized alternator!
Must be adding to the resistance of the crank shaft making it harder to start the engine putting an extra load on the starter which in turn made it draw more current.
Realised when I turned the engine by hand again the drive belt was slipping on the crank pully, not moving around at all. Removed the drive belt and everything spins freely apart from the alternator, can't get it to move enless its not meant to spin easily but I'm sure I should be able to move it at the least if not spin it.


So...now everything is in bits all over the garage floor, starter motor out again haha, engine pivot mounts at the bottom removed one, taken the bolt out of the other. coolant bottle, ecu wiring fuel filter and a mass of wires. Finished for tonight but should be able to get the alternator out by tomorrow afternoon, not the easiest of cars to work on if I'm honest, its a bitch to get at the alternator!

Thanks for your help guys. will post an update to let you know what happend, probably when I'm back from uni again next weekend.

P.s. does anyone know where to get a cheap alternator from?

paddycento said:

So...now everything is in bits all over the garage floor, starter motor out again haha, engine pivot mounts at the bottom removed one, taken the bolt out of the other. coolant bottle, ecu wiring fuel filter and a mass of wires. Finished for tonight but should be able to get the alternator out by tomorrow afternoon, not the easiest of cars to work on if I'm honest, its a bitch to get at the alternator!

Click to expand...

The alternator comes out from under the car, you don't need the remove the coolant bottle, ecu wiring, fuel filter or a mass of wires. You need to remove the dipstick tube, and depending on what current output alternator you have, you may need to remove the driveshaft.

Be careful not to lose the spacer from the top alternator mounting bolt, it usually falls out when you remove the bolt. It's dificult to get the spacer back in and refit the bolt at the same time. I hung the spacer on a spare bolt when I replaced my alternator a few weeks ago. If you refit it without the spacer, it's likely to break the aluminium mounting bracket.

You may need to lower the engine a little to get the top bolt past the chassis rail. Don't be tempted to refit it the opposite way round or it could rub on the auxiliary drive belt.
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Hi Davern,

I am bringing it out from under the car just couldnt get at the top bolt very easily so going to get a friend to hold a spanner from above while I try and get the T-bar in from under the car. Thanks for warning about the spacer that probably would have fallen and hit my face if not haha.

There's a thread about JTD 115 alternator replacement here: https://www.fiatforum.com/stilo/319572-jtd-alternator-change.html?p=3183641
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I have it out now will be ordering a new one tomorrow