S40 (New) Electrics : Wiring A Lights Left On Alarm And A Dashcam

[Bungo]

Amazed your battery gave out so badly and so suddenly. Anyway, problem solved and easily.
Hmm earths. Everything is "earthed" in that it is part of the loop that makes a circuit. Some items need a seperate earth as a branch from the loop, others remain part of the loop.
In theory all earths are live untill they terminate to earth. eg a switch will have a live entry and live exit, when it goes to a bulb it will be live in and exit to earth. The wire between switch and bulb is live.
In your case the A pillar connection should be ok.
Of course car electrics these days are not that straight forward as you know, especially with the canbus system.

[froggyted]

Originally Posted by Bungo

Amazed your battery gave out so badly and so suddenly. Anyway, problem solved and easily.
Hmm earths. Everything is "earthed" in that it is part of the loop that makes a circuit. Some items need a seperate earth as a branch from the loop, others remain part of the loop.
In theory all earths are live untill they terminate to earth. eg a switch will have a live entry and live exit, when it goes to a bulb it will be live in and exit to earth. The wire between switch and bulb is live.
In your case the A pillar connection should be ok.
Of course car electrics these days are not that straight forward as you know, especially with the canbus system.

Yeah, when the car wouldn't start after the Volvo Assist guy connected a donor battery, and was struggling to turn over, i thought i'd better come clean with what i'd been doing to give him some pointers. When i explained about my dashcam project he was adamant that my splicing into that earth lead would have done no harm, even when i explained that various items such as the ignition switch and passenger fuse box were earthed there or at nearby earth points, and further electrical tests he did on the vehicle confirmed that no electronic systems had been disturbed. However, when ten minutes later the car still wouldn't start i was seriously worried. After trying everything else he took the battery out and replaced it with a loan battery, which started the engine on first attempt. I must admit, i have had a couple of warnings about low battery charge on the DIM within the last week when i've been parked up for a few minutes with the engine off and accessories running, but no previous problems with starting. Of course, when i was working on wiring the dashcam the ignition wasn't on so received no DIM warnings before the battery flattened due, presumably, to the courtesy lights, footwell lights and boot lights running down the charge. The battery must have been well on its way out though to have refused to start the car this morning even with the aid of a donor battery, possibly at least one cell had failed. Overall, all's well that ends well, and the 30 mile or so round trip to Chippenham gave me ample opportunity to assure myself all the electrics were working ok.

I would really recommend Volvo Assist - especially as a freebie when you have your car main dealer serviced! I even got a 25% discount on a new battery by mentioning that i'd been forwarded by them, and fitted free, so a £79 high quality OEM component that should last at least another 7 years is money well spent, and better to have failed now than during the depths of winter. Therefore, to anyone reading this, if your battery is on its last legs and you have Volvo Assist you would benefit from calling them out to get the discount on a new one (as long as your battery fails their tests), particularly with all the other diagnostic checks they might need to do to get to the root of the problem. The guy that came out to me recognised me from last December when my engine went into limp mode after the DPF sensor failed (which he correctly diagnosed, then followed me all the way to the dealership at Chippenham). Very friendly, and with the time to explain and answer questions, and he even popped his head into reception for a quicK chat while i was waiting for the battery to be replaced this afternoon, after he came along to pick up the battery he'd lent me to get me there.

Anyway, back to the dashcam wiring! I'm just a bit reluctant now to earth back to that point at the base of the A pillar, despite assurances. When i was reading up last night to see whether i could have done anything amiss i came across a web article criticising the use of scotch lock connectors for a) sometimes cutting through strands of the wiring and b) leaving the exposed wire prone to possible oxidation and corrosion over a period of time. I had a quick look this morning and sure enough one or two strands of the earth wire seem to have broken, so am reluctant to damage any more with another splice. I might have a look at other options, and will report back when everything is up and running.

[froggyted]

Just a thought re wiring the lights left on alarm. Bungo mentioned something about my having possibly sent a spike through the canbus system when earthing the hardwire kit for the dashcam. As already mentioned, the problem seems to have been a dead battery - but i'm not completely convinced everything is ok because yesterday i went in to make a coffee and came out to see the lights were on, including dipped beam, despite there being no key in the ignition and the light switch being set to zero. Now this might be the infamous short-circuit in the loom to the boot switch issue, but i only replaced that about 18 months ago. Anyway, it's got me wary, and i must admit before working on the dashcam wiring i didn't remove the negative lead of the battery, which i now regret (what a faff that turned out to be due to dropping a screw into the tray - but more of that at a later date!).

Anyway, cutting to the quick, i'm just wondering whether, since i'm using a lights left on alarm that doesn't incorporate a relay but rather, has a current coming in at both ends as per the technique described here http://mgaguru.com/mgtech/electric/et245.htm and then, when one of these is turned off (viz. the ignition), the current passes through and trips the alarm, this could itself cause problems. The current obviously passes through the other end to an earth despite the fact that this would normally be a live feed. Could this upset the canbus / CEMs? Any thoughts?

[froggyted]

Here's a belated update to this thread, since both the dashcam and 'lights left on' alarm have now been successfully installed. I'm going to make two separate posts, one regarding the dashcam and the other for the lights left on alarm. Many thanks for all the advice i received, and which helped me to resolve these issues.

The replacement battery resolved the starting problem, no issues a year down the line.

The issues with the dashcam were almost certainly due to the hardwire kit supplied with the camera, which from some research on dashcam forums revealed is prone to send voltage spikes into the camera and fry it. Both my original and replacement dashcams (Mini 0806 - AVOID!) died within a week or so of hardwiring them.

I'm now running a Mio MieVue 618. It has one or two minor issues but is a far more reliable camera, and any issues that do present themselves are resolved by a quick reset.

My hardwiring solution was as follows: i connected the live feed, as suggested by paddyred, using a standalone cigarette socket via a piggyback fuse holder, into the passenger boot compartment aux socket fuse in the fusebox under the glovebox. (The terminals on the cigarette socket were taped up with electrical tape to ensure they don't short-circuit). The earth was made to a bolt behind the A-pillar trim that secures the front fasca panel, using a simple crimpable connector (after filing off paint from the bolt and using a torch to confirm that the bodywork thread was clean metal). The dashcam is therefore permanently powered on. This ensures that if i leave the car to go shopping or suchlike the camera continues to film, then enters a low-power parking mode state after a few minutes (this is selectable via the camera menu). If i want to disconnect the camera from the power supply i simply pull out the mini usb cable that plugs into the camera and is wired via the piggyback connection as above.

I will monitor this arrangement during the winter months. Some might be wary that this wiring setup could result in a depleted battery if the camera is left wired on (in parking mode) over a number of days. However, from past experience once the battery voltage drops below a certain level non-essential circuits are turned off automatically via the CEM and a message to this effect is displayed on the DIM.

[froggyted]

My eventual fix for the 'lights left on' alarm was as follows:

I located the correct wire, using the circuit diagrams in a Haynes manual, for the LED light on the main lighting switch (the switch is easily pushed out from the dash once you pull off the small side trim panel). This LED is illuminated at all times when the ignition is switched on, regardless of what position the light switch itself is in, and is also lit with the ignition is off if the parking lights are selected. I then tapped the relevant wire on the 'lights left on' alarm module, as per the instructions that came with the module, into this wire via a Scotch connector. (NB. these wires are of a very thin guage. Care needs to be taken to use the correct scotch connector for the job, and to not use undue force when forcing down the connection bridge on the connector with pliers, otherwise you could slice right through the wire in the loom).

The other wire in the module was connected via a piggyback fuse connector into the relevant fuse for the passenger compartment aux sockets at the fusebox beneath the glovebox. This circuit (unlike the socket circuit to the boot compartment that i used for the dashcam) is switched off at the same time that the ignition is.

The 'lights left on' alarm module was then fixed via velcro connectors to the plastic trim behind the floating control panel console, in such a way that it's clearly visible from the driver's seat (the module i used incorporates both an audible alarm and a flashing red led). (NB. It's important you are able to remove the alarm module easily, because otherwise this will impede the removal of trim necessary if you ever want to remove the floating control panel, for example if you needed to replace the trim or get to the audio head unit).

The 'lights left on' alarm therefore functions correctly so that you can then run the car with the parking lights and front fogs rather than the dipped main beam (the whole object of this exercise was to minimise unnecessary use of high intensity dipped beam bulbs such as Nightbreakers which have a much shorter service life than the OEM bulbs). If you inadvertently forget to switch the parking lamps off when you remove the key the alarm sounds, since the aux socket side of the circuit has now been switched off but the parking lamps left on ensures that the led in the light switch is still burning, allowing the current to earth through the aux circuit and sound the alarm. The front fogs, of course, automatically switch off with the ignition. (Incidentally, one of the very few criticisms i can make of the cabin design for this model is that the only warning you have that the front fogs are on is an led in the switch that is hidden by the steering wheel. Why on earth not have a warning lamp in the dash array, as per the rear fog light, and as per every other car i've ever had that featured front fogs including the S40 classic? There are even two or three unused positions in the warning lamp array that could have accommodated this).

With the module i have, the audible element of the alarm automatically switches off after about a minute but the led continues flashing until you turn the lights off at the switch.

There is a minor disadvantage with this setup in that, if you have an equipment level that incorporates the approach light feature, the alarm will also sound when you activate this via the key fob. This is imo a minor disadvantage, and overall the alarm has proved useful to me countless times since wiring it in.

None of the reservations i expressed earlier in the thread regarding wiring this module in came to fruition. There have been none of the feared erratic issues with the electrical system. When my DPF sensor failed 18 months after having had it replaced, with an associated warning of 'engine management service required' on the DIM, the main dealer assured me that wiring this accessory would not have impacted the electrics of the car.

Obviously, anybody else that undertakes this project does so at their own risk, and i can only state that, for myself, this project has proved worthwhile and will now extend the service life of my main lighting bulbs, whilst at the same time having a more fashionable setup of being able to run the front fogs instead of the dipped beam during conditions when daylight visibility warrants this.