Electrics: HELP! No dash display, electric seats etc.....

[Tom B]

Hello All,

Last week I jumped in the car - 2003 XC90 SE LUX and realised as I turned the key that there was no dash display, electric seats etc.
So I checked the fuses and Fuse 21 10amp - Extended Distribution I had blown. Changed this and all was good, or so I thought.

Well............. I got a frantic phone call off the wife this morning, no dash display, she cant move the seat. Its in my position. I'm 6'0 she's 5'0! So she cant reach the pedals to drive! We've ended up having to get the AA out to recover it.

Can anyone shed any light on this please! All help appreciated!!

[SwissXC90]

Originally Posted by Tom B

Last week I jumped in the car - 2003 XC90 SE LUX and realised as I turned the key that there was no dash display, electric seats etc.
So I checked the fuses and Fuse 21 10amp - Extended Distribution I had blown. Changed this and all was good, or so I thought.

Well............. I got a frantic phone call off the wife this morning, no dash display, she cant move the seat. Its in my position. I'm 6'0 she's 5'0! So she cant reach the pedals to drive! We've ended up having to get the AA out to recover it.

Can anyone shed any light on this please! All help appreciated!!

Let's analyse the Drivers Power Seat
The seat is powered by fuse 11C/3 (25A)
11C = Fuses in passenger compartment fuse box
This is a permanent power feed.
This fuse is labelled as '3. Power driver’s seat 25 A'

The wire runs from the fuse 3 to connector 54/25 then direct to the seat control unit (in the drivers seat)

Unplugging fuse 3 will stop power to the drivers power seat only
Likewise, fuse 4 will cut power to the passenger seat
I would carefully inspect the cabling under the drivers seat, look for chaffing and any sign of damage caused by movement (when the seat moves back and forth)

Fuse 11C/3 is fed by connector 54/40C, pin 1
Connector 54/40C is fed by fuse 6 (50A) on fuseblock 11E
Fuseblock 11E is mounted directly beside the battery in the boot
Fuse 6 on the battery fuseblock also powers F1 (Climate control fan), F3 (power drivers seat), F5 (left front door control module) & F6 (right front door control module)

So check if the fan blows, if it does, F6 is OK.


Now lets analyse the EXT. D fuse (extended distribution)
This fuse is F5 on the CEM

Looking at the wiring diagram, F5 powers:

• Multimedia display, XC90
• Control module, CD player (MP2), XC90
• Control module, MD player (MP1), XC90 (likely not fitted)
• Accessory wiring, infotainment EXT.D, XC90 (which runs under the drivers seat)

and primarily powers the audio system, including the nav computer and optional rear seat entertainment, including their displays.

AH HAH!
The nav drive is under the left-hand front seat
The audio amp is under the right-hand front seat
An infotainment display is built into the drivers seat.
Now we have some fault commonality, all focussed on power feeds running to the drivers seat area.
The problem went away and came back, which is a typical symptom of wiring chaffing.

My suspicion of wiring damage under the drivers seat has increased.


So get your torch, and your vacuum cleaner. Clean out the muck and dust and dirt under the drivers seat and inspect everything very carefully.
Look for water damage (sunroof leak) which may have affected the audio amplifier.
Look carefully for physical wiring damage through movement of the driver's seat, or through people in the back seat kicking the cables.


Focus on the power wires.

The power wires are coloured
Power for drivers seat:
Red to connector 54/25, then Blue with Red stripe to the power seat control in the actual seat

Power from EXT.D fuse F5
Violet from the CEM to junction 53/454, then
Violet to the Audio amplifier (under drivers seat)
Violet to connector 54X/112, then Violet to the DPY (nav display)
Violet to connector 54/112, then Violet to the ACC (Accessory, could be anything)
Violet to the OPN = Option (factory-installed)
Violet to the ICM (Infotainment Control Module (ICM), XC90)
Violet to the MMM (Navigation: Multimedia module (MMM), XC90)
Violet to the MP1 (MD player (MP1), XC90) / MP2 (CD player (MP2), XC90)

Let me know what you find

[Tom B]

That's awesome SwissXC90! Thank you!
I'm taking Friday off work so I'll be having a look then.
I'll take the drivers seat out and have a proper look at all the wiring. I take it this is fairly straightforward. Disconnect the battery for a start and then away I go?

[SwissXC90]

Originally Posted by Tom B

That's awesome SwissXC90! Thank you!
I'm taking Friday off work so I'll be having a look then.
I'll take the drivers seat out and have a proper look at all the wiring. I take it this is fairly straightforward. Disconnect the battery for a start and then away I go?

Yes, straightforward but be aware of the following:

1. The seat contains airbags (my MY2009 does), so after disconnecting battery, wait 15min for residual power to discharge before disconnecting any connectors on airbag systems

2. The seat is heavy, Volvo recommend using 2 persons to remove the seat. You must take great care not to damage any upholstery with sharp seat mounting brackets

Tip: take photos before you disconnect anything so you can be sure of what goes where

Good luck!

[Tom B]

I must thank you again SwissXC90, your advice was spot on!

I disconnected the battery, let the snow disappear (typical British weather when you need to get something done!) had a brew while waiting for any residual power to discharge from the airbags etc, then made a start taking out the seat.

This was nice and straightforward, 3 connections to the underside front of the seat, the plastic surrounds and then the 4 bolts for the runners.

Lifted the seat out - (on my own) you were right, its heavy!

Stripped the tape from the wires and inspected the insulation.

Eureka!!

Found 2 wires that the insulation had been rubbed through - pdf 1 (wont let me upload the photos - think the file is too big!)

So, stripped them back, spliced them, soldered them and put a decent amount of heat shrink over them too - pdf 2.

After that, I wound a decent amount of insulation tape around the loom. Not too much as to restrict the movement of the wires but enough to stop this happening again! - pdf 3.

I have also used a small cable tie under the seat to stop the loom from dragging on anything when the seat is moved.

With any luck, this will have sorted the issue!

Thanks again!
Tom.

[Acer]

Originally Posted by Tom B

I must thank you again SwissXC90, your advice was spot on!

I disconnected the battery, let the snow disappear (typical British weather when you need to get something done!) had a brew while waiting for any residual power to discharge from the airbags etc, then made a start taking out the seat.

This was nice and straightforward, 3 connections to the underside front of the seat, the plastic surrounds and then the 4 bolts for the runners.

Lifted the seat out - (on my own) you were right, its heavy!

Stripped the tape from the wires and inspected the insulation.

Eureka!!

Found 2 wires that the insulation had been rubbed through - pdf 1 (wont let me upload the photos - think the file is too big!)

So, stripped them back, spliced them, soldered them and put a decent amount of heat shrink over them too - pdf 2.

After that, I wound a decent amount of insulation tape around the loom. Not too much as to restrict the movement of the wires but enough to stop this happening again! - pdf 3.

I have also used a small cable tie under the seat to stop the loom from dragging on anything when the seat is moved.

With any luck, this will have sorted the issue!

Thanks again!
Tom.

The wires just look dirty in that pic not worn. Which ones had taken a beating? What would cause insulation to wear on these wires? Are they in a position where physical movement of the seat can cause problems?

Anyway nice work and well done to SwissXC90 for his astute diagnosis.

[Tom B]

Originally Posted by Acer

The wires just look dirty in that pic not worn. Which ones had taken a beating? What would cause insulation to wear on these wires? Are they in a position where physical movement of the seat can cause problems?

Anyway nice work and well done to SwissXC90 for his astute diagnosis.

Hi Acer,
If you zoom in to the area at the end of my thumb you can see where the insulation has rubbed through on the blue wire and the violet wire. Hard to see but you can just make out the copper strands.

The loom is under the seat and so every time it was moved there was the potential for the wires to rub on the heat sink for the amp of the frame of the seat. I think this is what has happened in this case, especially as the wife is 5'0 and I'm 6'0 so the seat is moved from one end of the runner to the other each time either of us drove it!

Thanks! Was an easy fix in the end thanks to SwissXC90!

[SwissXC90]

I am so glad you found the problem. And of course pleased I was right

The chaffing in your photo 1.pdf was exactly what I expected you to find - not easy to spot, as it only takes a little tiny bit of copper to shine through and then to short to chassis. But when you know where to focus your attention, it can save a huge amount of time.

It is worth pointing out to all readers that a good description of the problem really helped here. The fact that the drivers seat was being moved on almost a daily basis was a big red flag.

I've worked in automotive electrics and electronics for around 20 years and in that time you learn that anything that can move, will break.

And I love reading electrical diagrams, to me they are story books.

Well done Tom B, have a celebratory drink! Make sure you tell your wife you figured it our all by yourself

Greetings from SwitzerCrossCountryLand

PS: At the stage when I wrote my email, I had only owned an XC90 for the total period of 2 (two) days !

[mataei]

Hi Guys..

This is a great Post.
I have the same problem on my car.

Speedometer display,Clima Control and powerseat suddenly went completly black.

But i have one queston. I have a Norwegen car with the steering wheel on the left side.

On your picture i see the wireing over det amp. is that is on the left side in your car?

My amp is under the passenger seat.

Should i take out my left or right seat ?

Sorry for my pour english.

Originally Posted by Tom B

I must thank you again SwissXC90, your advice was spot on!

I disconnected the battery, let the snow disappear (typical British weather when you need to get something done!) had a brew while waiting for any residual power to discharge from the airbags etc, then made a start taking out the seat.

This was nice and straightforward, 3 connections to the underside front of the seat, the plastic surrounds and then the 4 bolts for the runners.

Lifted the seat out - (on my own) you were right, its heavy!

Stripped the tape from the wires and inspected the insulation.

Eureka!!

Found 2 wires that the insulation had been rubbed through - pdf 1 (wont let me upload the photos - think the file is too big!)

So, stripped them back, spliced them, soldered them and put a decent amount of heat shrink over them too - pdf 2.

After that, I wound a decent amount of insulation tape around the loom. Not too much as to restrict the movement of the wires but enough to stop this happening again! - pdf 3.

I have also used a small cable tie under the seat to stop the loom from dragging on anything when the seat is moved.

With any luck, this will have sorted the issue!

Thanks again!
Tom.

[SwissXC90]

Originally Posted by mataei

...
Speedometer display,Clima Control and powerseat suddenly went completly black.

But i have one queston. I have a Norwegen car with the steering wheel on the left side.
...
Should i take out my left or right seat ?

The amplifier is under the right hand seat on all cars (LHD and RHD)

But the wire can chaff on either the driver or passenger seat

Check both seats for any power wire chaffing under the seat.

Try moving the loom under the seat to clear if from any metal edges it may be running across and then fit a new fuse, raise the seat to max height and then inspect the loom carefully for chaffing