Clock, Fuel Door and Trunk Buttons stopped working on my 456M

Noticed a strange issue on my 456M today: the clock, fuel door and trunk release buttons all stopped working. Also when arming the car, the alarm will chirp 1 time followed by 4 chirps. I opened the fuse panel but didn't see a fuse relating to the clock, fuel door and trunk release buttons. The car is always plugged into a battery tender when parked.

TIA for your help!

 

NVM...found the culprit: since WSM doesn't show which fuse relates to the fuel lid, trunk or clock, I started to pull all the fuses. It was the #8 mini fuse.

I went to see how #8 mini fuse is labeled in the WSM and it simply says "+30 Services". Gotta love the Italians.

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Actually, +30 is a universal expression (in the automotive electrical world) for live battery power. "+15" is usually for power available when the ignition key is turned on.

In case you were wondering, Fuse 10 "+30 key" is power going to the ignition key (after which it becomes +15)

Anway, thanks for the tip! We have wiring diagrams, but it would have taken me a while to find the fuse.

 

Thanks so much for the info! Learning something new everyday. Would you mind sharing how you would've traced the wiring diagrams to find the fuse? I have the WSM but am not experience with this sort of things.

 

Unfortunately, the OEM 456M wiring diagrams are "hookup" diagrams rather than standard wiring schematics. I spent many hundreds of hours trying to convert the OEM diagrams to standard wiring schematics. There is a steep learning curve involved.

For example:

You have to realise that the OEM graphics of connectors are seen from the back of the connector (where the wires go in).
The graphics of the fuseblock "26D" (also seen from the rear) are rather strange with square and T shaped contacts. The square contacts represent the incoming power from the "Maxi" fuses (I've forgotten where they are on the 456M). The fuseblock fuses are between the square and T shaped contacts.

The fuse you replaced outputs to splice S50D (see the back of chapter D) on an RV (red/green) wire. There are 12 wires in the splice! From the splice, there is a red wire going to the clock (which is part of 20E). You also have to figure out which wire is which on 20E which has an 8 pin connector.

Anyway, here's my diagram showing the clock:

https://www.dropbox.com/t/WNfR8JcEpnFcrr7k

The fuseholder 26D is shown on the far right of the diagram.

The maxi fuses are shown on a different diagram.....and the trunk switch on another diagram.... It's quite a rats' nest. Note that I have reversed the image of the fuseholder to make it more user-friendly. If I include graphics of connectors, I also reverse them to show the face of the connector (e.g. on the pin/socket side). This makes it easier to do wiring checks.

 

Thanks Ian! Very helpful and much respect for your hard work.

 

Note the four extra alarm chirps tell you a body panel is not closed. Makes sense with your fuel door and trunk/boot being disabled.

 

Almost a month later the same fuse was blown during today's drive. Tracing back here are the only three things I did during the drive:
- turned on the Radio: switched to CD, FM and Bluetooth
- turned off A/C by pressing the STOP button
- turned the Fan speed dial from 2 to Auto back to 2

I know the fuse was blown during the drive, b/c I opened the trunk button to load a bag and when I got to the gas station (about 10 min later) the fuel & trunk buttons no longer work. So something is causing this 15 amp fuse to blow...anyone recommend how I should approach this?

TIA!

 

When the fuse blows, have you attempted to start the engine? In theory, this fuse will stop you starting the engine. The fuse literally powers everything connected to the ignition switch. The list is endless.

I'm currently revising the circuit relating to the starter. After that, I'll try and make a list of everything connected to the ignition switch.

 

Even after the fuse is blown, I have no issue starting the car. I only notice the fuel door, trunk and clock don't work.

Thanks Ian!

 

Sorry, I was getting my +30 and +15 fuses mixed up.

Fuse 8 supplies power to splice S50D which, as you have discovered supplies power those components. S50D powers also powers a surprising number of other components.

I'll make a list for thes other components. In the meantime, check your trunk light (perhaps a shorted bulb?).

 

Here's the rest of the components on the list...

The fuse also powers the driver's and passenger's door lights (door open/door sill lights). Again, look for shorted bulbs. Does the problem usually occur when a passenger is being carried?
Are the front and rear dome lights working when the fuse is ok?
Sun visor light?
You don't have a Canadian car, so that eliminates a daytime running light issue.
I'm guessing you don't have the mobile phone option?

Have you checked the trunk and fuel door systems one at a time to see if they blow the fuse?

Unfortunately, you may need a dozen spare fuses as you systematically work through the different systems. Maybe a cheaper option would be to pull the fuse and then check each lamp with multimeter.

 

Thanks Ian. Will check these items tomorrow and report back. Btw, would you send me the link to the electrical diagram again?

 

Here's a lighting diagram which shows some of the connections...

https://www.dropbox.com/t/0UuLHnYkZb4i4xp3

It shows the connections to the frunk light and the pushbuttons for the trunk/petrol cap

I just realised that is some of my diagrams, fuseblock "26D" is shown from the rear of the fuseblock (and also oriented vertically instead of horizontally). The wiring diagrams show a very odd representation of the fusebock with squares and T symbols which is very hard to understand.

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The squares represent the hot sides of the fuses. I think power comes in on the right side of the fuseblock on the hot side of fuses 1, 5, 9 & 13. Battery power from the hot side of fuse 5, for example, is fed to fuse 6, 7 & 8. Fuse 8 is the fuse which is blowing. Anyway, this is probably going too deep for the moment.

The door wiring is shown in this diagram:

https://www.dropbox.com/t/mbBkm5FnYlUj2Fzc

Power from fuse 8 is fed to pin 14 of each main door plug.

 

Here's the diagram for the clock, but it's unlikely this would blow a fuse.

https://www.dropbox.com/t/ugQkH2YlGT3FE9o9

This diagram is a work-in-progress. I haven't been able to figure out the starter circuit yet. I may need some input from you on this later Don't put the cover back on the relay panel just yet.

 

I'm deceptively unintelligent, but whatever you need...be happy to help out.

 

Apparently, 456M has a relay which stops the car starting if an OEM battery charger is fitted (and powered). It's named 37D in the wiring diagrams. It should be one of the grey plastic rectangular relays sitting above the main relay panel. i.e. sitting in one of these combined relay/fuse holders:

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The fuse may be entirely unrelated to the relay circuit. The number of relays and fuses fitted depends on whether the car is a GT or GTA.

Anyway, there should be a relay/fuse holder with the following wire colours:

red
unused
white with black stripe
white with green stripe
black
red
white
I don't know if the two reds are the same size.

Would it be possible for you to identify the relay/fuse holder with those wire colours going to it? (using the photo above as a reference). Are there any socket numbers marked on the holder (on top or below)?

e.g.

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If possible, could you tell me which sockets of the holder are carrying live (dc) battery voltage (including the fuse socket)? i.e. put the red probe of your voltmeter on the sockets (one at a time) and the black probe to a good earth (with the ignition turned off).
Then turn on the ignition and see if there is ignition volts on the remaining pins.
Then, if you turn the ignition to start, do you get any volts on the remaining, remaining pins? The car shouldn't start because the relay has been removed, but you may still get volts.

TIA.

(EDIT) This is the only way I could get the relay to operate correctly...

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I've removed the pin numbers from the fuse/relay holder until wiring checks can be done.

 

Hi Ian, I'm away on vacation at the moment. Be happy to do it when I'm back on the 30th. I'll send you my number so we can trade texts and speak if necessary.