Occasional stalling when flashing main beam

[TheLeeds]

A belated update on this.

It was the battery.

I'd noticed that if left for a week or so, the battery would lose some charge and be unable to start the car. The other clue, as I think I mentioned earlier, was that at the same time, and also when the engine stalled, the stereo would lose it's presets.

I had a spare battery lying around, so I put it in a couple of months ago. I didn't want to jump the gun or tempt fate, but since it's had a different battery in, it's been fine.
I'm guessing there's an internal fault in that battery.

Anyway, many thanks again for all your help and ideas.

[TheLeeds]

Originally Posted by TheLeeds

.......since it's had a different battery in, it's been fine.........

Until now.
It's done it again a few times recently.

[Laird Scooby]

Sorry to hear that - i'd seriously check all the earths as i previously described/suggested. It sounds like the most likely scenario to me.

[TheLeeds]

Originally Posted by Laird Scooby

Sorry to hear that - i'd seriously check all the earths as i previously described/suggested. It sounds like the most likely scenario to me.

I checked all the earths I could find, including the ones at the front of the inner wings, and behind the front kick panels by the lower front door hinges. They were all good and clean with no sign of a connection problem on any of them.

I also checked and cleaned all the under bonnet ones including engine earths which seem good as well.

The bit that's puzzling me the most is that when it happens, it cuts all power to the car totally, as if the battery has been disconnected. This is evidenced by the way the stereo goes off and loses it's presets, just like they do if you disconnect the battery. Do these cars have a thermal fuse anywhere that could cause this symptom if faulty or overloaded ?

Or what about the ECU ? Mine's an R reg 2.3 lpt car with what I understand is the later ECU wired immobiliser. Could a fault in there produce these symptoms ? I've got a spare ECU but it's off an earlier 2.0 car, so I'm not sure of the year or compatibility.


I wondered if it could be the ignition switch, but even if it caused stalling, I don't know if it would cause total power failure (as in the disconnected battery scenario). Unless I've just got really unlucky and fitted a battery which has now developed the same fault ?

[Laird Scooby]

Sometimes an earth fault will only show up once the cable is warm andit's usually where they go round a bend. It could also be a bad terminal on the battery or perhaps a partially broken cable onto the battery that only moves enough once it's warm to break the circuit.

You'll need to go methodically along each heavy earth cable and also the positive cables too just to be certai and basically twist or bend the cables while the radio is on so you can hear when something effects it. Also give the wires into the earth crimps the "tug test" - try pulling the wire out of the terminal.

If all is good, even a fairly aggressive tug won't do any harm, if ther'es a problem you'll have the answer in your hands - literally!

Your suggestions/ideas are very valid although none would cause the loss of the radio memory so it's either a major short circuit (possibly from the +ve starter feed to earth) or an earth that is breaking and making.

You'll just have to be methodical, rigorous and a bit aggressive i'm afraid!

[mocambique-amazone]

I would check now the connection between 30 on the battery and the power terminal 15/1
On lhd cars it is on the blower unit behind the glovebox
If I remember right on rhd cars behind the glove box too. It is a flat black box. A few red wires goes into this. Maybe the wire from the battery to this is broken or corrosion inside this box. (Not common) measure if there is a voltage drop between the battery and the box outlets with engine running and lights and radio and blower on.
I won't believe on a problem of the ignition switch.

Good luck, never had this problem, Kay

[TheLeeds]

Wanted to use the car yesterday. Started it up (just dipped beam headlights and stereo on). Engine was running hesitantly. This was accompanied by a whirring, buzzing and clicking noise through the stereo speakers. The engine stalled, and did the same the first time I restarted it. 3rd time, it ran fine.

Originally Posted by mocambique-amazone

.........flat black box. A few red wires goes into this. Maybe the wire from the battery to this is broken or corrosion inside this box. (Not common) measure if there is a voltage drop between the battery and the box outlets with engine running and lights and radio and blower on..........

I took out the glove box today and checked out all the wiring behind it. Couldn't see a flat black box like you've described, and all the wiring there looks and feels fine. We ran the car with the main beam headlights, stereo and heater fan on, whilst moving the wires about, and as always when you want to get the symptoms to show themselves, nothing happened.

[mocambique-amazone]

I forgot about the position of 15/1, sorry. The last rhd 940 I did dismantle is 5 or 6 years ago. Since he did. A suizide with a deer together I don't own a rhd 940 anymore, for bad luck.
Hopefully other are able to help with a information about the location of this flat black box with a few red wires.
I think you have a voltage drop at your 940. All the current to the fuse box is running throug this box. Locate this item, check if there is a voltage drop under load.
Good luck, Kay

[Laird Scooby]

Always a difficulty when transferring knowledge based on RHD to LHD and vice versa. Very few manufacturers stick to a common loom and some parts will inherently be different simply because the controls are on a different side.

Others change the control side of the loom and leave everything else in the same place while some simply "mirror image" the entire loom using the same loom regardless of market and just flipping it over to change between LHD and RHD - either way it causes a lot of confusion!

[aardvarkash10]

Hey guys. I'm with Kay on this for sure. There is only ONE location that is common to the run, radio and light circuits and its the component identified as 15/1 in the Volvo wiring diagrams. It carries the main live feed circuits from the battery to the inside of the vehicle, and then distributes those feeds.

The wiring diagrams I have show this box as fitted to either the r/h front pillar OR l/h front pillar / firewall / dash area. It will have EITHER five OR seven red wires entering it. I'm presuming its left or right depending on left or rhd, but the manual is unclear on that.

Find this box, open it and look for signs of a loose connection - it may look burnt or melted, it may have a physically loose connector - hard to know at a distance of 15,000km.

But I'll buy you a pint if this isn't the location of the fault.

The wiring diagram (Volvo official) I am referring to can be downloaded here. ITs a VERY large but incredibly useful file