Re: Car wont start: problem found
Thanks to everyone for suggestions.
I think I have solved the problem
I have checked the wiring using FIAT eLearn: part codes are provided. The supply from the IGN 30A Maxi fuse, B5, to the ignition switch, H1, seemed fine: this is a Red/Black (RN) cable to the centre pin (30) on the 3x1 connector, H001A, on the back of the ignition switch. A Brown/Black (MN) cable goes from pin (50) on the same 3x1 connector to pin G on a 7 pin connector, D004B, (which I have yet to find) and then on as a Brown/Black cable to the starter motor solenoid. (The third pin is for ABS while the other connector on the back of the ignition switch, H001B, is for other things (clearer when you zoom in E5010 on eLearn)).
So the Red/Black cable is the feed to the ignition switch (see 5520A12) and the Brown/Black cable is the feed to the starter motor solenoid, through connector block D004B. When I checked at pin 50 on the ignition switch I got a fluctuating voltage suggesting a poor supply or faulty switch.
(Note: Perhaps someone could explain how with the supply to the actual starter motor (30) coming directly from the battery and earthing through the casing the motor doesn’t run continuously? Is there is a relay inside the solenoid so that current only flows after the pinion has engaged with the flywheel ring gear?)
If I turn the key all the way I could hear a quiet click but not from the starter motor or starter solenoid, probably just a relay behind the dashboard. There is no ‘attempt’ to turn the engine but there is a slight current drain which takes the battery down from say 11.9V to settle at 11.7V. The battery is now re-charged to 12.5V.
This suggested to me that there were 6 possible conditions: the first two mechanical and the other four the result of an open-circuit.
1) My first thought had been that the starter motor might be seized because of all the rain since Christmas, though everything had been fine before I started doing the handbrake. Picked up a new one cheaply and fitted it – no difference.
2) My second pessimistic thought was that having stood unused for 4-6 weeks while I did the handbrake may have led to one or more cylinders containing coolant water as a result of an unsuspected cylinder head failure. Again no symptoms of this were noticed before laying the bug up. I thought I had ruled that out by foolishly towing the car about 5 yards in 5th gear (foolishly because I could have made the timing belt jump or break and possibly bent one or more valves or conrods!). I have since easily turned the engine 3 complete turns counter-clockwise by using my torque wrench on the 19mm socket on the bolt holding the auxiliary belt pulley so have ruled out this possibility. Turning in the clockwise direction was not possible but I don’t know why.
3) I ran FIATecuScan which returned 3 errors which all reappeared after clearing. The first was glowplugs which said FATAL ERROR. I wondered if all 4 had failed meant the ecu aborted the start up. Knowing that it is generally agreed that the Multipla doesn’t need glowplugs to start when temperature is above –10 I discounted this.
4) The ignition switch might be faulty. I ruled this out by checking for continuity over pins 50 and 30 after disconnecting the cable connector H001A and fully turning the key.
5) Lack of continuity between pin 50 on the ignition switch and pin 50 on the starter solenoid.
My multimeter wouldn’t reach so I disconnected the solenoid cable and ran a jump lead to the disconnected Brown/Black cable by the ignition switch. Continuity OK
6) The connection at the 30A blade maxifuse at B5 (by the battery) might be suspect so allowing an adequate feed to the instrument display but not the higher current needed for the solenoid. The fact that I had an episode of constant relay clicking and incomplete testing when just turning the ignition on would support this especially when it was ‘cured’ by twiddling the ignition maxi fuse. I first dismantled the B5 maxifuse casing and checked the bolt below the 4 fuses was fully tightened: it was. The maxifuse feeds Pin 30 at the ignition switch which is the Common to all the connections inside the switch including the pin 50 to the starter solenoid. Using the blade of a screwdriver I ‘crimped’ the female fuse holder ends to ensure tighter contact with the blades of the fuse.
After all this I did manage to get the engine to turn a little on the key but only like you get when the battery is almost flat. Same result when a second good battery was attached with jump leads.
Putting my thinking cap on, the fact that I could only turn the engine by ‘hand’ anti-clockwise but not clockwise (thinks there is a freewheel pulley on the alternator…), the absence of any rotation on the key, the current drain which could only come from starter motor trying to work led me to another possible mechanical condition that the alternator had seized. Removing the auxiliary belt confirmed this as the engine started immediately.
Now to find a cheap new Denso Dan501 105A alternator…
