Centre console electrical problem.

[Uncle Tom Cobley]

The car is a 2004 1.9D Sport, one of the very last.

A problem has developed with some of the electrical equipment. I first noticed it when I locked the car; while the doors locked and the security light on the upper dashboard blinked the hazard warning lights did not flash (once).

I later realised that several other electrical parts no longer worked, these are:

Hazard Warning Lights
Left & Right Seat Heaters
Rear Window Demister
Heater Blower
Air Conditioning (but this could be due to the heater blower not working).
Cigar Lighter
And importantly the Brake Lights.

From the wiring diagram I have, the Haynes Manual for the Petrol V40 which only shows typical interior and engine bay fusebox layouts, these various pieces of electrical equipment are supplied by various different fuses and all the fuses I have checked are OK. I’m not sure however I can rely on this manual as the fuse layout differs from the owners handbook.

About the only commonality to the problem is that all these switches, except the brake lights switch, are located in the central console area. While I cannot imagine how it might have happened it occurs to me that a multiple connector somewhere behind the centre console has become loose or detached. The radio however works.

As far as I have found all the other electrical equipment switched from the drivers seat works OK, i.e. radio, lights, indicators, wipers, washers, exterior mirror adjusters.

It seems unlikely the problem is in the engine compartment as it appears there is more than one engine compartment fuse involved.

Having read through various postings I notice that a common electrical problem is the wiring harness beneath the radiator, but again there seems to be more than one cable involved. Do all the electrical supply cables from the engine fusebox to the interior fusebox really run to the front of the car, then under the radiator and back to the interior?

I’m reluctant to start stripping out the dashboard if the problem lies elsewhere. Does anybody have a reliable wiring diagram to these centre console switches or have any thoughts on this problem? Most of the non-working parts I can live with temporarily but having no brake lights is not good.

Thanks.

[Darlo 1]

I had exactly the same problems on my v40d when I got it, the first place you need to check is the wiring loom that runs under the radiator, you may find a few wires that are corroded or broken, mine were and caused the exact same problems that you have now, hope this helps you out.

[Uncle Tom Cobley]

Thank you Darlo1, this is very interesting and helpful. I had pretty much convinced myself that the problem lay within the centre consul/fusebox area so I will take a look at the radiator area.

As a matter of fact a very strange thing occurred when I used the car this evening. When I switched on the ignition the seat heater, demister and air-conditioning switches lit up for about 5 seconds then went out. They continued to blink on and off about every 5 seconds approximately 10 times before staying off. Most peculiar! This led me to think it is not a straightforward wiring/electrical problem but something much more complex involving one of the various electronic control units which seem to control almost all the vehicle electrics. Diagnosing a problem in one of these ‘black boxes’ is beyond my electrical knowledge and ability.

I haven’t yet given up and taken the car in for a diagnostic check and your message gives me reason to keep looking. I believe one of the first things I need to do is to determine whether there is power in the cabin fusebox, if there is I imagine this would eliminate any problem within the engine bay area.

So far you are the only person to have responded. There are some bright and knowledgeable people on this forum; can this problem really have beaten them all?

Thanks again.

[Darlo 1]

You may also find that there may be no power to the diagnostic socket either, the lack of brake lights points me to you having a short in the loom, under the radiator is the common place for this but I also believe that the loom continues somewhere around the o/s/f wing area. On mine it was just four wires that had gone but took out the same components as yours, checking for power or lack of at the fuse box inside the car should confirm a break in the wiring at some point.

[Uncle Tom Cobley]

Thanks again Darlo1. I’ll check the diagnostic socket.

I’ve managed to find a wiring diagram for the 2004 V40 and am now struggling to understand and follow it. Just taking the basic brake light as an example I find the supply starts at the battery, goes through fuse #1 in the engine bay, then through fuse #2, then fuse #3, then to the passenger bay fuse box #13. Then the stoplight switch, then the SEM (where it appears to get involved with the cruise control, automatic transmission, bulb failure unit etc!) and finally to the light bulbs. Phew!

[Uncle Tom Cobley]

I owe it to the members of this group and especially to those who responded, to report back on this problem. I never cease to be surprised and disappointed by the number who write asking for help, receive helpful advise, but then never report back providing details of what they found and how the problem was solved for the benefit of other members. Is this selfishness or laziness, or both?

The fault was indeed in the main wiring loom where it runs by the side and under the radiator. The problem has now been fixed and I think a few comments would be helpful to others with similar problems, it is not intended to be a step-by-step guide. While the car was a 2004 1.9D much of the following will apply to most models.

This turned out to be an all day job, at least 6 hours, although I’m pressed to explain why it should have taken quite so long.

First I needed to establish whether the problem lie between the engine bay and cabin fusebox or some place after the cabin fusebox. The first thing I discovered was that the probe on my small electrical test meter would not fit into the gap for the mini fuse holder to enable me to check whether there was incoming power to the fuse holder. To overcome this I made up a test lead; I soldered a 12-volt bulb to a length of wire and a crocodile clip to the other end. I then soldered a second piece of wire to the other bulb contact, bared a 10mm length the other end which I then also soldered to keep it rigid when inserting it into the fuseholder. This worked fine.

This enabled me to establish the problem was before the cabin fusebox and so the radiator had to be removed; moving it slightly will not provide sufficient access. Next I found the four bolts attaching the two top radiator brackets to the body were well and truly rusted in. It took me ages to slowly ‘work’ these free as I didn’t want to break away the captive nuts which are inaccessible. I replaced these with stainless steel bolts.

I’d previously replaced both top and bottom radiator hose clips with stainless steel and they came undone easily. The very large hose clip holding the turbo ducting to the front cooler however was completely rusted and had to be cut off. I replaced this with a stainless clip.

I then removed the radiator, complete with fan (and turbo cooler). I did notice the two bottom screws retaining the fan housing to the radiator were well past removing, mostly rusted away; fortunately I didn’t need to separate this from the radiator.

I did not find any wiring connectors in the radiator area of the wiring loom so I could not remove it from the vehicle, however I had to cut the plastic ties supporting the loom to the under radiator area; I wasn’t able to replace these. I then cut round the woven nylon mesh sleeving exposing the cables. There are about 30 cables here, all differing colours and stripes (and I’m colour blind!). Fortunately when I slid this mesh sleeving back it immediately became very obvious where was the problem, a large Red cable looked as though it had burst and was very corroded; all the other cables were fine. Amongst all these cables are two very much thicker cables, a large White one and this large Red one; these supply a large current direct to the ignition switch (the White one) and the cabin fusebox (the Red one). It seems to me that if you have multiple electrical units that have failed then it’s almost certain to be one of these two large cables, all the other (smaller) cables I suspect supply just individual electrical units.

It is worth noting here that some of the units that apparently operate only when the ignition is switched on are actually supplied through the large Red cable, it is the relays that actuate them that operate through the ignition switch. This can be confusing when identifying electrical faults. You really need to check the Volvo wiring diagram for your model and year; fuses, supply routes etc appear to vary considerably by model and year and by which extras/accessories were factory fitted. I would add that I’m not convinced that even the Volvo wiring diagrams are 100% reliable; for example the wiring diagram shows the heated seats on my vehicle operate through the ignition switch yet they are actually supplied directly through this Red cable (via a separate fuse in the fuse box). So be warned.

Now to repair the break. This is a thick cable and I did not have a piece this size, the copper stands themselves are approx. 3½mm in diameter. Nor did I have a suitable means of connecting the two. Fortunately I have a very helpful neighbour, he brought over two large crimp connectors that had a central hole of 4mm, a length of suitable wire (I only needed about 3cm) and best of all a professional ratcheting connector crimping tool, this did the job very well. Having joined the cable I checked the various electrical units and they all worked!

Since I had cut away some part of the mesh sleeving I needed to replace this. I used a length of bicycle inner tube, slit open to wrap round all the cables and secured it with cable ties. This should keep most of the water away and protect it from chafing. When I replaced the radiator I was still concerned about chafing as I’d cut the cable ties attaching the loom to the body and so inserted some small pieces of foam between the loom and the radiator. I was thinking about this later, after I finished the job, and realised that ideally I should have wrapped this part of the loom in a length of pipe foam insulation (I’m not certain whether 22mm would have been large enough, or whether I would have needed 28mm).

So, to recap, here are some of the special items you’ll probably need for this job and it’s wise to make sure you have these before you start:

A test meter with a sufficiently small probe to go into the mini fuse holder.

Stainless steel hose clips for both the radiator hoses (and an approx. 9cm clip for the turbo hose on the 1.9D).

Four M8 stainless steel bolts about 25mm long (for the radiator brackets).

A short length of cable (preferably Red) with an internal strand diameter of at least 3½mm, it has to carry up to 40 amps.

Two large crimp connectors with a central hole at least 4mm in diameter and a suitably large crimping tool.

A length of heatshrink insulation large enough to go over the cable connectors (approx. 10mm in diameter).

A length of suitable sleeving to re-cover and protect the loom. I think it probably best to cover the whole of the loom covered with the nylon mesh, maybe 75cm.

For those unable to spend the whole of a day on this job a considerable amount of work can be undertaken separately before hand, e.g. identifying the locality of the problem, freeing all rusty bolts and hose clips, removing the engine under trays (oh, how I hate those wretched under engine trays and clips!) etc. I’m sure these jobs took up more than half the time.

I’m still left wondering what caused this corrosion. Water would not in itself be the cause as copper is generally unaffected by water, I therefore assume it was due to the salt used in the winter. But surely this would not have burned through the cable outer covering, and the rest of this Red cable all the other cables seemed fine.

Any theories?

[mikelan]

thanks for this. Brilliant wrote up. I'm always keeping an eye out for potential problems and how to fix them if they turn up on my car. Hopefully won't happen to me but at least I will know what to do if it does.

[pacman67]

Looks like I'll investigate the loom then.