ECU fuse blown on 4200

JonH

Junior Member
Messages
390
Some advice please guys.

4200, 57 Reg, one of the last to be made.
Went for MoT end of October, needed new wheel bearing and took weeks to get it, due to poor communication between dealers and out of date stock lists.
Whilst waiting for bearing, battery went dead, despite me sending my CTEK trickle charger with the car as well known problem. New battery fitted, full reset done with code etc but car won't start. Never been an issue before in the 4-5 years I have had the car.
Car has now gone to FTECH for diagnosis. The 30amp fuse to ECU keeps blowing when trying to start. I am told, a new ECU may be needed. Sounds very expensive and it was fine when it went in!!!!!
Looks like this may have happened in past as the fuse was not original.
I have trawled the forum as best I can and found a similar issue with a 3200, but the thread never finished so not quite sure what outcome was.
Before this gets completely out of hand has anyone got any ideas, thoughts, solutions etc.
Would be much appreciated
Thanks
 

FIFTY

Member
Messages
3,100
I'm sure someone will come along to help... out of interest did they try to jump start your car when the battery failed?
 

davy83

Member
Messages
2,809
The fuse for the ECU should not be 30 Amps? Was the correct fuse changed for a heavier one at some point? Certainly the ECU cannot draw more than 30 amps and still be ok, so unless there is damaged wiring then the ECU is probably goosed. Does the fuse blow just switching the ignition on and not starting the car? If so pull the big connector out of the ECU and switch on the ignition see if the fuse still blows? This would increase the confidence that the ECU is at fault. also if you remove the ECU and the fuse still blows you know its not the ECU. I am also wondering if the car was jump started, the 3200 and 4200 with the battery way up the back do not like jump starting. Try some of the breakers for an ECU before committing to a new one, I think second hand from a working car would be ok.
 

JonH

Junior Member
Messages
390
Mmmm I had the same thought. They are experienced guys and work with a lot of high performance and classic cars so I would be surprised if they did as they know the consequences. There may be a difficult discussion to come if the ECU is fried.
Thanks
 

conaero

Forum Owner
Messages
34,593
My initial thought was the car has been jump started and could have goosed the ecu?
 

FTECH

Sponsor
Messages
14
Hi JonH.

Yes, unfortunately your car came into us last Thursday from the Haynes Museum workshop with this non starting issue and we have been looking into the cause of the fault.

We found that fuse 46 which is a 7.5amp fuse (not 30amp) was blown and that it was a non standard fit fuse as it had an LED which was illuminated showing it had blown. Also we cannot communicate with the engine ECU. We are currently continuing investigations as to why your car won't start and would welcome a call from you if you want to discuss further. 01392 829599.

We often have Maserati's and Ferrari's in from Haynes when the issues get too technical....as is the case with your car.
 

Spartacus

Member
Messages
3,184
Phone Maserati Stuart , he ll have an ECU i would think.

Your car is in the right place . Tim and Dan from F tech will sort it . They is the nutz :thumb3:
 
Last edited:

hashluck

Member
Messages
1,515
For my education what is the issue with jump starting? Is this if from another car? Is it OK to use one of those jump start battery packs if battery dead?

Not had any issues yet but want to be prepared. I have no facility for a trickle charger before anyone suggests it but I use the car regularly anyway.
 

safrane

Member
Messages
16,748
From what I understand the spike in power can damage the diodes embedded in the wiring looms.
 

conaero

Forum Owner
Messages
34,593
Jump packs are usually a higher amperage than what your electrical system uses...70amp plus 100amp = :atishbazi:
 

philw696

Member
Messages
25,114
To be fair guys i have been using a jump pack since they first came out and with every Dealership I have ever worked with and never had a problem.
Its down to the quality of the jump pack and thats why you only buy a Professional one and not one for $50.
I only have seen one goosed car and that was by the Sales Exec at Maserati jumping a new QP with the wrong polarity and it did more than one ecu.
 

rockits

Member
Messages
9,167
I was on the understanding that jumping from a battery pack was generally OK as the car takes the juice it needs and no more. It is also offers a smoother better sustained voltage.

I understood it be an issue when using jump leads from another car as spikes and big variances in voltages seem to happen this way. I was always told if you had to jump with leads from another car then to turn the headlights on full as if anything will blow it will just be a bulb or light fuse.

It could well be wrong but this is what I have heard and been told over the years. I have used jump packs for years on numerous high performance cars and never had an issue. I won't use jump leads anymore on nicer cars but not so bothered on the older tougher daily's.

It makes sense to me jumping with leads would be potentially damaging for any car when you think about it. Also that jumps packs are a better way of jumping by design.

Just my 2p's worth
8
 

voicey

Member
Messages
660
I promised myself that I wouldn't post on another jump start thread but here goes...

The danger lies from jump starting a from a really flat battery. When the jump pack (or other car) is connected to the dead car it provides a good 12-14V on the dead cars electrical system. This allows the car to start and the alternator to start working.

So far so good - everyone is happy, until the good power source is removed. At this point the load seen by the alternator suddenly changes. The rectifiers in the alternator are not quick enough to change the output and a spike occurs (over a time period measured in mS).

Turning the lights and demister will increase the load so the net change in load when the good power source is removed is less.

If you must jump start then if you're using another car it'd be better to let the good car charge the bad battery up and disconnecting before starting. If using a jump pack then let the engine run for a while before switching off. Disconnect the pack and restart.
 

davy83

Member
Messages
2,809
What he said! I think its also affected by the condition of the battery in the car, failed batteries can develop high impedance internally and this means they don't regulate the 12v properly, and removing the jump leads can lead to spikes as the load, and regulation of the 12 changes, especially problematic in cars with the battery mounted at the opposite end of the car from the engine.

I promised myself that I wouldn't post on another jump start thread but here goes...

The danger lies from jump starting a from a really flat battery. When the jump pack (or other car) is connected to the dead car it provides a good 12-14V on the dead cars electrical system. This allows the car to start and the alternator to start working.

So far so good - everyone is happy, until the good power source is removed. At this point the load seen by the alternator suddenly changes. The rectifiers in the alternator are not quick enough to change the output and a spike occurs (over a time period measured in mS).

Turning the lights and demister will increase the load so the net change in load when the good power source is removed is less.

If you must jump start then if you're using another car it'd be better to let the good car charge the bad battery up and disconnecting before starting. If using a jump pack then let the engine run for a while before switching off. Disconnect the pack and restart.
 

hashluck

Member
Messages
1,515
Great info many thanks.

Will be interested in the expert opinion on the following advice I got.....

I would like to trickle charge my battery but have no mains electricity in the garage (nor any means to connect once of those solar powered thingies). The advice in this case was to take a fully charged jump pack and connect it to the battery during the lay up period. It will effectively trickle charge the battery. Then before starting remove said jump pack and start car as normal (and recharge it ready for next storage period).

Thoughts? Seems safe and reasonable to me.
 

CatmanV2

Member
Messages
48,547
Well it's not going to trickle charge the car's battery as they will have the same voltage. Effectively you've just put a bigger battery in your car, which will have more charge left after a given period of time. So you might be OK.

How long are you laying up for? If it's weeks / months I'd probably just take the battery out and keep it on a conditioner somewhere else.

If it's days, the jump pack will probably do it, but you'll need to take that in every so often and charge it up.

C
 

FIFTY

Member
Messages
3,100
When I was living in my old place I had a car port with no power supply. I chewed through one battery by leaving the interior light on which is on me but the new bosch S5 battery never let me down under normal locked/alarmed conditions and I ran the car in winter every 2-4 weeks.

Since I moved to this place I have a garage and eventually bought a C-Tek and the car seems slightly happier on the initial crank but it's not that noticeable
 

hashluck

Member
Messages
1,515
Thanks all. Car will only be left for 2-3 weeks and battery is fairly new. So will just lock and leave as normal and only use jump pack if batter ever runs too low and using advice above.
 

JonH

Junior Member
Messages
390
Thanks for the advice guys.
Have had a chat with Tim at FTECH will wait and see what comes of their investigations.
I concur with many of the comments on here about jump starting, trickle chargers etc....I do know that in the firsts 6 months of owning the car I had a variety of 'issues' which all went when I bought the CTEK. Seems to need a battery that is in good condition and fully charged. If I go on long trips, such as Le Mans this year, then I take one of these:

https://www.amazon.co.uk/RAVPower-1...186&sr=8-3&keywords=ravpower+car+jump+starter

Haven't had to use it as yet, but others on the forum have with no problems.