Fuse 16 Blows Vertical Acceleration Sensor Repair

conaero

Forum Owner
Messages
28,481
#1
With thanks to SteveM for the following how to guide:

Following my previous post I have received a number of PM's requesting a guide on how I fixed the problem of Fuse 16 so here's my first attempt. As you will appreciate this has been my first real baptism of Maserati ownership and I am sure there will be others who will be able to add improvements in terms of how to remove the lights more easily which I would welcome but this is a guide on how I fixed it.

For a start if you have the workshop manual the problem part is the "Vertical Acceleration Sensor" detailed in the Suspension Sensor chapter pages 9 & 12. Unfortuantely I could not locate any way to disconnect the device remotely to eliminate or confirm this is the cause of teh fuse 16 without getting to the sensor itself.

The sensor location is behind the near (left) side headlight and indicator unit and the only way to get to it is to remove these items:
A) Remove wheel and wheel arch liner in front of wheel (exposing rear of intercooler)
B) Remove grille - 4 screws at the top and with slight leverage pull the bottom away from clips
C) Remove Air filter cover and filter
D) Headlamp - disconnect connector. The headlamp is held in by three nuts. The easiest to remove is at the back of the lamp. The next you can get to following removal of air filter from engine bay. The third one is a pig towards the front of the headlamp and is underneath. I did this with aid of a torch and 10mm ratchet spanner working from the side of the lamp and via the grille opening. The headlamp unit then slides forward out of car but you might need to consider protecting paintwork with tape.
E) Sidelight/indicator unit - again disconnect connectors and undo nut at back of unit onto plastic bracket. There is a second nut is underneath the unit which is again tricky to get to and you have to undo working blind with 10mm ratchet spanner.

Hopefully the sensor is now accessible as photo below indicates (with yellow label):



F) I tried undoing the sensor directly from bracket but this started to distort so I would recomend disconnecting connector from sensor (small retaining clip) and undo the bracket from bodywork. It was at this point you will hear the tell tale rattle to confirm you have identified the source of your fuse 16 problems



G) Working at a bench I then removed sensor from bracket.
H) I would then strongly recomend marking lid with base of sensor as it can be fitted 2 ways and you will want to get it correct when you refit. Then with small screwdriver you will need to clean sealant from screwheads retaining lid. Once lid removed you will find a loose block of metal (brass?) which has been shorting out connectors within sensor.





I) Having cleaned out sensor of dust and small areas of corrosion, I then used small screwdriver to clean off old grey glue and then re- araldited metal block back onto base. There is an outline on base to position it. I actually cut a piece of insulating tape lengthways and fixed to top of block to help position and then retain in position until glue set (I used rapid set araldite which took about 10 minutes). I also used some clear mastic to ensure good seal around joint and screws. The photo below shows block back in position.



J) Reinstallation is just a reverse of processes above.I fitted another fuse before re-assembly just to check. Fitting the two awkward nuts on the two lights is the most awkward trying to position from above. I would also suggest you check that you have fitted all connectors correctly to the lights before fitting wheel arch liner as I discovered the following night that I have forgotten one on the side light.

K) Anyway the good news is that once refitted all the airbag warning lighst and suspension "ERROR" light no longer showing on dash. Test drive last night and all systems seem to be functioning as normal.

Good luck if you having a go at thsi yourself - it took me about 3 hours but then I was on a steep learning curve. For the price of some glue, mastic and scraped knuckles I think I may have saved over £600 for a new sensor plus labour.
 

Emtee

Centenary Club
Messages
8,446
#2
Brilliant Steve. Perfectly clear. Thanks for making the effort to photograph your work and document it here. Regards, Miles.
 

SteveM

Centenary Club
Messages
416
#3
Just a quick update to the how to guide. When I turned my side lights on for the first time since doing this repair I had the dash light indicating a bulb had gone. After some investigation I realised I had wrongly re-connected the indicator and side light connectors back to front. So I would strongly recomend you check the lights and indicator before you refit the headlamp - the correct way is the white connector in the middle and the black to the outside (indicator) otherwise you will be going through all the pain again!
 

bossemaserati

Centenary Club
Messages
142
#5
good morning! i was looking at this and somehow the pictures in the first post do not seem to be on the thread anymore.. have these disappeared from the forum? thanks!
 

SteveM

Centenary Club
Messages
416
#6
Hopefully Matt can fix otherwise I can try and find the old photos and upload again. Let me know if there is a particular image you are after and I can pm to you
 

Ian3200

Junior Member
Messages
772
#7
Mike Roberts did this for me yesterday, no scraped knuckles for me ;-) very satisfied customer, and a world away from £600!
 

Ian3200

Junior Member
Messages
772
#9
Did you have fuse issues then Ian?'
Upon heavy acceleration out of a 50 limit the airbag and ERROR lights came on, it was the vertical acceleration sensor that broke, shorted out and blew fuse 16... the same fuse does the indicators rather annoyingly... Mike sorted me out ;o)
 

wink

Junior Member
Messages
85
#11
Mike also fixed the exact same fault on mine (well, I think it was accelerating out of a 30 limit, but with just the same scary result).
 

Moz1000

Junior Member
Messages
656
#12
Many thanks Steve - I've just done this on my car as I have had Fuse 16 blow twice.

Just one point for anyone attempting this - you don't need to take the side light unit out; you can remove the Acceleration Sensor by removing the screws for the bracket and it just lifts out from behind the light unit.

Dave
 

MUC3200GT

New Member
Messages
111
#14
D) Headlamp - disconnect connector. The headlamp is held in by three nuts. The easiest to remove is at the back of the lamp. The next you can get to following removal of air filter from engine bay. The third one is a pig towards the front of the headlamp and is underneath. I did this with aid of a torch and 10mm ratchet spanner working from the side of the lamp and via the grille opening.
Hi Conaero

I am popping this thread up again, as I am wondering how you managed to re-mount this 3rd nut during reassembly ?

regards

Jörg
 

SteveM

Centenary Club
Messages
416
#16
Hi Jorg - its over 4 years since I did this so strugling to recall exactly how I did this - perhaps someone will reply who has done it more recently. there is very little space so you have to use a ratchet spanner and not ratchet socket. Its then just a case of using fingers to get nut into position and then using ratchet to tighten nut
 

MUC3200GT

New Member
Messages
111
#17
there is very little space so you have to use a ratchet spanner and not ratchet socket. Its then just a case of using fingers to get nut into position and then using ratchet to tighten nut
Yes, there is so little space that I cannot get the bolt into position. The problem is when I reach with my flat hands I can easyly get to the point, but when my hand holds the bold its impossible to get the the right point (for me, maybe someone with a smaller hand could do).

Also I am wondering whether the mounting kit has changed for later cars. As the workshop manual tells "working form the front opening (grill),slacken the screws fastening the the headlight support bracked.." So the term screws (more than one) might point that not the headlight should be unmounted form the support, but the support bracket as such (which seems not to be possible in my car). But it could be that the maintenence manual is wrong as it also doesn`t mention the bolt behind the air filter.
 

MUC3200GT

New Member
Messages
111
#18
or could it be an option the remove the foglight and do it from the foglight grill hole ?. The direction and parking light plug are accessible quite easy, but the second bolt (under the support bracket) and the fog light plug, I havent figured out how to remove with the main light installed. The parking and direction lights are simple turn and plugout of the Foglight assembly, also the plugs can be disconnected by pressing the metall bar, but the foglight plug I have not yet understood how to remove.

FoglightExcerptMarked.jpg

At least for the 4200 this seems to be an option
 

MUC3200GT

New Member
Messages
111
#19
Just to be complete: finaly it was pretty simple: with my left hand I could insert the bolt into the mounting hole. Than it hangs without support in the threads and with my other hand I could reach there again and schrew it in. It needs some luck that the bolt doens`t fall down in the bumper nirvana.

Final fixing was possible with a tiny cranked spanner which I recently bought on a flee marked (note: its good old east german quality form smalcalda)

smalcalda10_11cranked.jpg

With my straight ratchet spanner I could not reach the bolt