Technical Fuse F3 Keeps Blowing

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Technical Fuse F3 Keeps Blowing

BrianMcL

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Hi, the latest issue is that it's started blowing the 20amp maxi fuse in the main fuse box.

There doesn't seem to be anything wrong with the car and it starts fine, except when that fuse blows and then the only things that work are the interior lights and then clock. The rest of the dash is completely dead.

Has anyone had this before or have any ideas about what could cause it?
 
Electric steering motor i think.Try disconnecting the steering motor and replace the fuse.
 
I think it's the power steering fuse.

It seems to be working fine but I guess it might be starting to fail. Is there any way to check?
 
Bit strange for a motor to go short circuit,they normally go open circuit,or the brushes get stuck in the holders.Maybe a resistance check?It must be servicable,worth opening it up to look at it.
 
Hi,
Thought I'd replied to this earlier,but it seems to have got lost.
Fuse F3 (20A) in the fuse box next to the battery is for the steering LOCK, not the power steering. Is the steering lock working OK, you can hear the motor run a few seconds after you pull the key out? When does the fuse blow? if it is when you put the key in or out it's likely to be a faulty lock module, either an electrical fault or a seized motor / gearbox.
Could also be a chafed wire, try unplugging the lock module (mak sure it's unlocked first) and see if the fuse still blows.
One issue if it is a faulty lock module is that these are coded to the other immobiser modules (Key module, body computer and ECU IIRC) so you need either a virginised module or have to change the whole set. Where are you located?

Robert G8RPI.
 
Hi,
Thought I'd replied to this earlier,but it seems to have got lost.
Fuse F3 (20A) in the fuse box next to the battery is for the steering LOCK, not the power steering. Is the steering lock working OK, you can hear the motor run a few seconds after you pull the key out? When does the fuse blow? if it is when you put the key in or out it's likely to be a faulty lock module, either an electrical fault or a seized motor / gearbox.
Could also be a chafed wire, try unplugging the lock module (mak sure it's unlocked first) and see if the fuse still blows.
One issue if it is a faulty lock module is that these are coded to the other immobiser modules (Key module, body computer and ECU IIRC) so you need either a virginised module or have to change the whole set. Where are you located?

Robert G8RPI.


Hi Robert,
Thanks again for the advice. I'm in Paisley.


It's been parked up for most of the last year so might damp / corrosion be a potential cause of the problem?


It's not making the sort of whirring sound when I put the key in or take it out but until you mentioned it above I hadn't even noticed!


The fuse blows when I try and turn the key and because it's for the steering lock I understand now why everything except the clock and the interior lights goes dead.


Would starting with the lock module be sensible and if so how would I go about unplugging it?
 
Hi Robert,
Thanks again for the advice. I'm in Paisley.


It's been parked up for most of the last year so might damp / corrosion be a potential cause of the problem?


It's not making the sort of whirring sound when I put the key in or take it out but until you mentioned it above I hadn't even noticed!


The fuse blows when I try and turn the key and because it's for the steering lock I understand now why everything except the clock and the interior lights goes dead.


Would starting with the lock module be sensible and if so how would I go about unplugging it?


Hi,
The lock module is on the steering column and unplugging it would be the next move. I don't recall exactly where on the column it is. You can download the eLearn service manual from the download section and it will help explain access. The eLearn is a bit of a faf being a 3 part RAR archive of a CD-ROM image that you then have to burn to a CD-R and install. There is some guidance on here if you search the Croma posts. ePer (link on blue bar of forum page may help too. I'm at work and can't access eLearn or ePer at the moment.
If it's been left for a while it sounds like damp and corrosion may have got into the lock module and caused it to seize. This will cause excessive current and blown fuse. It might be repairable though. If unplugging it stops the fuse blowing, take the lock module off the column and inspect it. Address any obvious issues like corrosion. Then try it not mounted to the column.


HTH,
Robert G8RPI.
 
I've never been able to get eLearn to run on any of my computers. Goodness only knows what I do wrong :confused:

I've taken the plastic housing off the steering column but I'm not sure what the lock module looks like to disconnect it.

Would anyone have an ebay link or the search term for eper?
 
Tried setting up elearn on my new win10 laptop and it was a doddle!

Is the part possibly causing the problem labeled M089?
 
Nice - have a great time!

I got stuck in to it today and what I've found is as follows:
The steering lock is mounted on the base of the steering column with the connector on the left hand side. The connector is secured by a purple clip which slides to the front of the car and the connector comes away very easily.

The control unit can be reached from the foot well above the clutch pedal.

I couldn't find all of the screws, etc. to get all of the trim off but if anyone else needs to tackle this job don't bother undoing them - you can reach in from front and back to connect and disconnect the unit.

Whilst I haven't taken the unit itself out yet the car won't start with it disconnected.

The unit looks as though it's held on to the steering column by 2 nuts / bolts and when I take the unit out I'll post back about whether there's anything else to it.

Car seems to be working OK just now but I'll be happier once I've had it out and had a proper look at it.
 
Hello, i have the same problem. How did you solve it permanently? Thanks a lots
 
Welcome to Fiat Forum.
BrianMcL can you give us an update?

Robert G8RPI.
Hello everybody, here it's my ultimate solution for the problem of this post, that i'm going to share with you.

I searched for the WIRING DIAGRAM about the F3 Fuse.
The Problem is about the section of STARTING AND RECHARGING of the car.
 
WIRING DIAGRAM

E5010%20AVVIAMENTO%20E%20RICARICA%20-%20SCHEMA%20ELETTRICO-2.jpg
 
Last edited:
Component code / Description
A001 BATTERY
A010 ALTERNATOR
A020 STARTER MOTOR
B001 ENGINE COMPARTMENT JUNCTION UNIT
B002 JUNCTION UNIT UNDER DASHBOARD
B099 MAXI FUSE BOX ON BATTERY
C002 BATTERY EARTH ON ENGINE
C003 BATTERY EARTH ON BODYSHELL
C020 PASSENGER SIDE DASHBOARD EARTH
D001 FRONT/DASHBOARD COUPLING
D004 FRONT/ENGINE COUPLING
D097 SHORT CIRCUIT COUPLING
E050 INSTRUMENT PANEL
H003 IGNITION DEVICE
I031 CLUTCH PEDAL SWITCH
M001 BODY COMPUTER
M089 STEERING LOCK CONTROL UNIT (NBS)
 
FUNCTIONAL DESCRIPTION

.. The steering lock control unit M089 provides a power supply from the direct battery line protected by fuse F3 of the engine compartment junction unit B001 - pin C1 and, depending on the rotation of the key in the ignition device H003, receives the following signals:
- at pin A6, the key inserted signal (TEG_IN);
- at pin B5, the key turned to ON signal (TEG_MAR);
- at pin C5, the first starting signal with the key turned to START (TEG_Crank1);
- at pin C6, the second starting signal with the key turned to START (TEG_Crank2);
..
Turning the key at the same time to START, from pin B8, the steering lock control unit M089 sends the +50 signal to the starter motor A020 solenoid winding (pin 50, connector C).
Pin 30 (connector A) of A020, the actual motor, receives a power supply with the voltage coming from the battery A001.
 
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