V8 Vantage MY07 - Boot/trunk lights not working

[Chad-h4oel]

Hi all,

Trying to work out which relay and or fuse is responsible for the boot lights. The ones where you open the boot and you get light to see whats in there - there are 2 of them, one on the left, one on the right. Both have blown. I suspect a fuse, but without know which fuse, its like searching for a needle in a haystack.

Any ideas anyone please?

Thanks in advance.

[LTP]

The schematics should be in the back of your handbook. If you don't have one you can download the correct one here:

https://www.astonmartin.com/en-gb/owners/owners-guides#results

My 15MY manual says it's F17 (5A) but that's for Roadster only - no idea which one it is for my 15MY Coupe

[Chad-h4oel]

Thanks LTP

What was the name on your roadster? Ill see if I can find the similar one on the coupe?

[LTP]

Chad-h4oel said:

Thanks LTP

What was the name on your roadster? Ill see if I can find the similar one on the coupe?

The exact wording for Fuse 17 in the 15MY manual is "Boot lamps - Roadster"

Knowing how Aston Martin Tech Pubs have been known to make copy/paste errors, if my Coupe lamps went out I'd start by looking at fuse 17.

[SpawnyWhippet]

Same issue here. Fuse 17 is connected to ground, lights don't work. The schematics do not list the relay functions either. Anyone fix this yet?

[bullet7]

The wiring diagram in the 2005 workshop manual seems to show Fuse 47 as being the one supplying power to the lamps in the boot/trunk. Try there.

[Jon39]

LTP said:

The schematics should be in the back of your handbook. If you don't have one you can download the correct one here:

https://www.astonmartin.com/en-gb/owners/owners-guides#results

My 15MY manual says it's F17 (5A) but that's for Roadster only - no idea which one it is for my 15MY Coupe

Don't forget the Valkyrie owners guide.

Extract;
'Service Intervals
Caution: Use of this vehicle in a track environment can drastically reduce the life of some of the below components.
Always contact your Aston Martin Dealer before this vehicle is used on track.'

I thought this model was built as suitable for track use.
Disgusted of Tunbridge Wells, would demand his money back. -

[SpawnyWhippet]

I checked every fuse, all were good. I think there is something more sinister, as the vehicle also doesn't know the trunk is open and allows operating of the cabriolet roof which 'interfered' with the paint on the boot lid. It also doesn't notify you of the boot being open, unlike all the other doors/bonnet.

[Mercdriver]

I got caught out by an old Merc, same problem. Could it be that the parking lights have to be on before the boot light will work? I spent two hours tracing the wires from fuse box to lights then the penny dropped, most frustrating!

[bullet7]

SpawnyWhippet said:

I checked every fuse, all were good. I think there is something more sinister, as the vehicle also doesn't know the trunk is open and allows operating of the cabriolet roof which 'interfered' with the paint on the boot lid. It also doesn't notify you of the boot being open, unlike all the other doors/bonnet.

You should have mentioned your model, as this thread was on an earlier Coupe! The fuse is likely to be a different one in that case. However, the principles remain the same and the important thing is whether you you have power running to the lamps, as you should have? Power is fed directly from the fuse to the lamps and the circuit is then made (making the lights come on) through the motor operating the latch. If you have power at the lamps, then the motor/latch is likely to be the fault; if not, then it is more likely to be a break from the fuse to the lamps. Presumably, you have also checked the bulbs themselves.

If you do have power at the lamps, you should also check the wiring to the motor/latch before assuming it is the motor, just in case there is a break there. The motor also operates as a relay telling the Central Electronic Module that the boot is open or closed. This will be why you were able to operate the roof, as the module is under the impression the boot is closed all the time.

[bullet7]

Looking at the wiring diagram, relay no. 6 located in the fusebox within the boot/trunk and connected to fuse 17 could also be the culprit if faulty. You really ought to get a circuit tester on the wiring to check supply/earth.

[LTP]

SpawnyWhippet said:

I checked every fuse, all were good. I think there is something more sinister, as the vehicle also doesn't know the trunk is open and allows operating of the cabriolet roof which 'interfered' with the paint on the boot lid. It also doesn't notify you of the boot being open, unlike all the other doors/bonnet.

I've done a little internet digging and, assuming the diagrams I've found are still valid (and changing the way something like a trunk latch works is unlikely to be modified during a model life), then the switch to tell the car whether the trunk is open is incorporated within the trunk latch, in the lid.

The fuse appears to be Fuse 17 and the relay involved is Relay 6



As you can see from the above image, Relay 6 is also implicated in communicating with the CEM concerning whether the trunk is open, probably so the CEM will know whether to operate the convertible roof.

I also found a circuit diagram (relevant bits highlighted)



This confirms the switch is in the latch, and it also shows that the latch switch is closed when the trunk lid is closed - you can see the pin for "Boot Open" (Boot being UK-speak for Trunk) has no wire going to it. So the trunk is wired so that the switch should be closed and sending a signal when the trunk is latched - which indicates to me that there isn't a break in the wiring, or a bad earth, otherwise there wouldn't be a signal and the car would think the trunk was open.

My suggested next steps? You've checked Fuse 17 (assuming it's the correct one) and it's good. This would only affect the lamps themselves, and would not be involved in the signal to the roof. The next bits depend on your confidence

1. Try swapping out Relay 6 for an identical neighbouring one. I doubt that this is the culprit, but it's worth a quick check, as from the wiring diagram it's implicated in the roof CEM signal
2. Remove the trunk lid trim off the inside of the trunk lid - multiple "fir tree" fasteners. You'll probably need a forked plastic trim tool to lever them out as a screwdriver can scratch stuff, but I have gotten this type of fastener out in the past with some patience and multiple screwdrivers and steel rulers
3. If you can reach the connector on the latch and can work out how to release it (they are sometimes "latching" connectors so they don't vibrate off) pull off the connector. Depending on how the car reacts to the open circuit, the trunk lights could possibly come on and I would expect the roof to refuse to open. If I'm right then "Happy Days" - it looks like it's the switch.
4. If you can get to the pins of the connector when it's off (depends on how much slack there is in the harness) from the diagram I think Pin 4 should be earth and Pin 1 should be the feed to the switch to tell the car the trunk is closed. If you short these then the boot lights (if on) should go out and the roof should work (obviously be careful as your trunk will be open - but you know this).
5. Removing the latch from the trunk lid should be 2 or 3 bolts and it'll come away through the inside of the lid. There may be a rod to the emergency release handle, which should snap and unhook (I'm guessing here - you'll have to work it out on the fly from what you see).
6. Once you have the latch out you should be able to check the switch with a multimeter and using a bar or screwdriver shaft to engage the latch pawl. I'd expect the switch to have failed "closed". If so then I think it'll be a new latch as I don't think the switches are serviceable and you probably won't be able to get to its workings without dissembling the latch. Maybe some switch cleaner and several operations, but if it's failed closed it's usually mechanical.

One other possible scenario, depending on how long you've had the car and if the lights and the roof interlock have ever worked, is someone has permanently shorted across the switch as a "bodge" to get the roof working for sale, because they didn't want to fork out for a new latch.

Hope this helps a bit. Usual disclaimers of ....at your own risk..., yada yada.

As that's all my imaginings (backed up with a little related experience, but not on an Aston) I'd be interested in how you get on. Unless you blow the car up, then I was never here

Edited to revise Pin numbers as I initially got them wrong , and to add the following:

One further thought. Assuming the latch switch appears to be worked OK electrically, if the wire feeding the latch switch had shorted to earth then that would also create the symptoms you have, as this would always tell the car that the trunk was closed, You could check this by seeing which pins on the connector go to earth - I'd expect maybe Pin 4 to earth, Pin 1 not, based on this earths diagram



The connector references tally nicely, which gives me some confidence.

Edited by LTP on Tuesday 27th February 12:29

[SpawnyWhippet]

LTP said:

I've done a little internet digging and, assuming the diagrams I've found are still valid (and changing the way something like a trunk latch works is unlikely to be modified during a model life), then the switch to tell the car whether the trunk is open is incorporated within the trunk latch, in the lid.

This confirms the switch is in the latch, and it also shows that the latch switch is closed when the trunk lid is closed - you can see the pin for "Boot Open" (Boot being UK-speak for Trunk) has no wire going to it. So the trunk is wired so that the switch should be closed and sending a signal when the trunk is latched - which indicates to me that there isn't a break in the wiring, or a bad earth, otherwise there wouldn't be a signal and the car would think the trunk was open.

My suggested next steps? You've checked Fuse 17 (assuming it's the correct one) and it's good. This would only affect the lamps themselves, and would not be involved in the signal to the roof. The next bits depend on your confidence

1. Try swapping out Relay 6 for an identical neighbouring one. I doubt that this is the culprit, but it's worth a quick check, as from the wiring diagram it's implicated in the roof CEM signal
2. Remove the trunk lid trim off the inside of the trunk lid - multiple "fir tree" fasteners. You'll probably need a forked plastic trim tool to lever them out as a screwdriver can scratch stuff, but I have gotten this type of fastener out in the past with some patience and multiple screwdrivers and steel rulers
3. If you can reach the connector on the latch and can work out how to release it (they are sometimes "latching" connectors so they don't vibrate off) pull off the connector. Depending on how the car reacts to the open circuit, the trunk lights could possibly come on and I would expect the roof to refuse to open. If I'm right then "Happy Days" - it looks like it's the switch.
4. If you can get to the pins of the connector when it's off (depends on how much slack there is in the harness) from the diagram I think Pin 4 should be earth and Pin 1 should be the feed to the switch to tell the car the trunk is closed. If you short these then the boot lights (if on) should go out and the roof should work (obviously be careful as your trunk will be open - but you know this).
5. Removing the latch from the trunk lid should be 2 or 3 bolts and it'll come away through the inside of the lid. There may be a rod to the emergency release handle, which should snap and unhook (I'm guessing here - you'll have to work it out on the fly from what you see).
6. Once you have the latch out you should be able to check the switch with a multimeter and using a bar or screwdriver shaft to engage the latch pawl. I'd expect the switch to have failed "closed". If so then I think it'll be a new latch as I don't think the switches are serviceable and you probably won't be able to get to its workings without dissembling the latch. Maybe some switch cleaner and several operations, but if it's failed closed it's usually mechanical.

One other possible scenario, depending on how long you've had the car and if the lights and the roof interlock have ever worked, is someone has permanently shorted across the switch as a "bodge" to get the roof working for sale, because they didn't want to fork out for a new latch.

Hope this helps a bit. Usual disclaimers of ....at your own risk..., yada yada.

As that's all my imaginings (backed up with a little related experience, but not on an Aston) I'd be interested in how you get on. Unless you blow the car up, then I was never here

Edited to revise Pin numbers as I initially got them wrong , and to add the following:

One further thought. Assuming the latch switch appears to be worked OK electrically, if the wire feeding the latch switch had shorted to earth then that would also create the symptoms you have, as this would always tell the car that the trunk was closed, You could check this by seeing which pins on the connector go to earth - I'd expect maybe Pin 4 to earth, Pin 1 not, based on this earths diagram

The connector references tally nicely, which gives me some confidence.

Wow, thank you for that detailed information, I am very bad at interpreting wiring diagrams so that really helps! I have checked fuse 17 and tested all the relays, all are good. I pulled the boot lid panel off and took a look at the wiring for the latch, which appears to be a Volvo unit. The latch still works from the button and the fob, so I would assume if there is an issue there, it is the microswitch that detects latch position. I guess that is the part that has the secondary connector with black and orange wires going to it?



So, I disconnected the connector to the latch and the trunk lights immediately sprang into life. I guess that means the latch microswitch is bad?

Edited by SpawnyWhippet on Friday 15th March 20:32

Edited by SpawnyWhippet on Saturday 16th March 00:25

[LTP]

SpawnyWhippet said:

Wow, thank you for that detailed information, I am very bad at interpreting wiring diagrams so that really helps! I have checked fuse 17 and tested all the relays, all are good. I pulled the boot lid panel off and took a look at the wiring for the latch, which appears to be a Volvo unit. The latch still works from the button and the fob, so I would assume if there is an issue there, it is the microswitch that detects latch position. I guess that is the part that has the secondary connector with black and orange wires going to it?



I'll try that troubleshooting and report back.

You're welcome - I just hope I got it right.

Looking at the diagrams again, I would expect just one plug from the car’s harness to go into the latch assembly, the plug having three wires. I couldn’t find a colour key that Aston use, but if they stick to one of the conventions I found (an outside chance knowing how quirky Aston can be, unless Ford reined them in) I would expect the wires to be:

• an orange wire with a blue stripe (OU) - this is the signal feed from the CEM (Central Electronic Module) to the microswitch in the latch that detects if the latch is closed or open
• a white wire with a green stripe (WG) - this is the power feed from the CEM that operates the latch motor to open the latch
• a black wire with a yellow stripe (BY) - this is the common earth for both the latch motor and the microswitch

The Aston wiring diagrams don’t show any of the latch internal wiring - it basically regards the latch as a “black box”. If my guesses about the number and colours of the wires in the harness plug that connects to the latch are correct then you may be able to use those to trace the internal latch wiring.

If you can get a multimeter set to “continuity” then when the latch is operating correctly I’d expect there to be a connection between the OU and BY wires when the latch is closed and an open circuit with the latch open. If my assumptions about the fault are correct, my guess is that you'd see a connection between OU and BY whether the latch is open or closed. Without power you can open the latch using the manual override from the emergency handle

Edited by LTP on Saturday 16th March 00:26

[SpawnyWhippet]

So, I disconnected the connector to the latch and the trunk lights immediately sprang into life. I guess that means the latch microswitch is bad?

[LTP]

SpawnyWhippet said:

So, I disconnected the connector to the latch and the trunk lights immediately sprang into life. I guess that means the latch microswitch is bad?

That would be my guess. It can't be a bad earth otherwise the latch wouldn't operate, as from the diagram they share a common earth wire.

As I said in Step (3), I'd also expect that, with the plug pulled, your roof won't work either.

Edited by LTP on Saturday 16th March 09:02

[LTP]

I just thought I'd add a word of caution (forgive me if I'm teaching you to suck eggs)

If you're anything like me you're going to take out the latch, confirm that the microswitch has malfunctioned, and then try to remove it from the latch body to see if you can work out why it failed and if you can fix it. If the switch has failed then it has currently failed "closed circuit". If you mess with it, it could end up going irredeemably "open circuit" - this will put your boot lights on permanently and, even worse, stop your roof from working. I doubt that it would stop the actual latch from working, but I'm not privy to the fiendish internals of the Volvo latch so you never know.

Before you start trying to fix the microswitch I'd make sure that the roof is in a position where you can live with it (closed?), that you know which fuse to pull to extinguish the boot lights (they were not designed for 24/7 illumination) and after you've fiddled with it that the latch still operates before you close the boot lid. Or you could just short out the switch if it goes OC.

Good luck.

[SpawnyWhippet]

So, the fault was the microswitch in the old trunk latch. I ordered a replacement Volvo latch with the same PN from ebay, installed it and immediately the trunk lights came on and the vehicle recognized the trunk was open on the dashboard. When I close the trunk, the lights go out and the warning on the dash disappears. All looks good now.
Thanks for your assistance, much appreciated.

Edited by SpawnyWhippet on Thursday 28th March 00:04

[LTP]

SpawnyWhippet said:

So, the fault was the microswitch in the old trunk latch. I ordered a replacement Volvo latch with the same PN from ebay, installed it and immediately the trunk lights came on and the vehicle recognized the trunk was open on the dashboard. When I close the trunk, the lights go out and the warning on the dash disappears. All looks good now.
Thanks for your assistance, much appreciated.

Glad to have been a small amount of help