Paranoia?

[jvrenaudon]

I am presently in the thick of another restoration and sorting out the electrics on my Series 2 CSI - a car which stood for over 10 years out in the open, gradually filling up with water from blocked sun-roof drains. All connections, earths, spade-ends, switches, etc., had developed a build-up of crud and crust which meant that they were all suspect. Switching on the indicators resulted in the lights dimming in synch with the flashers - the sort of thing you see every day on our roads- indicative of bad earths; you get the picture.

So, I set about going through the car, front to back, cleaning up every connection back to brass or bright metal, even installing supplementary earths where I thought they would benefit. I thought I'd cracked it until I sat in the car last night in fading light, turned the ignition on (without cranking the engine) and tried the indicators. The ignition warning light and the oil-pressure warning lights still fade slightly in synch with the flashers. This is on a newly charged-up fresh battery. The "fade" is very slight but it is noticeable.

Thinking that this still indicated a fault, I got into my relatively recently-restored CSL for comparison and tried the same exercise and was surprised to notice exactly the same phenomenon - the warning lights fade slightly to the time of the flasher relay. Is this a characteristic of the car or simply a throwback to 1970's wiring and something that I'd failed to notice before? Surely the drain from two indicator bulbs is not sufficient to cause a slight but detectable dimming in two tiddly warning lights. I would be interested to learn if this afflicts other cars. Best wishes, John

 

[sfdon]

Try the groundless turn signal relays that are available.
They don't share the same ground connector that the dash bulbs use just the turn signal filaments.
Also try it when running the engine.

 

[adawil2002]

Curious what makes a Series 2 CSi?

 

[Arde]

My warning lights in mine stay solidly lit regardless of what other function I turn on.

My battery is one day old. The old one croaked on my return from Legends, and the toolbox cracked. Speaking of paranoia I am starting to suspect saboteurs from other marques did that to me while I was roaming the venue.

Maybe one way to determine if it is a voltage drop on the ground path vs the battery drain is to repeat the test with the engine running at 2k rpm or so. In this case the alternator can provide additional current to compensate for any extra drain, but the alternator cannot help voltage drop on a poor ground. If dimming still happens I would blame the ground, if it does not happen I would blame the battery. This assumes the ground path is common to these circuits and the 12V is dedicated per circuit for the most part.

 

[jvrenaudon]

Paranoia

Don, Arde, Thanks - good tips. The problem is , though, that the fault (if it is one) disappears because, when you start the engine, the lights go out completely, naturally! I am still left wondering if this is then a hidden fault - hence the paranoia. The idea of a groundless relay is appealing - will make enquiries about these.

The Series 2 is to distinguish VIN4350001 to 4350207 from the earlier VIN 2260001 to 2265508. These earlier models are believed to be rhd as converted by BMW Concessionnaires - also referred to a Phase1. The Series 2 were built as rhd. Best, John.

 

[jmackro]

Is this a characteristic of the car or simply a throwback to 1970's wiring and something that I'd failed to notice before? Surely the drain from two indicator bulbs is not sufficient to cause a slight but detectable dimming in two tiddly warning lights.

My guess is that your coupe is fine and that the current drain from two indicator bulbs is sufficient to cause a slight but detectable dimming in two tiddly warning lights.

The power consumed by a resistor equals voltage squared / resistance. A bulb is pretty close to a fixed resistor and its light output is proportional to the power it consumes. So a 3% voltage drop would result in a 9% decrease in light output.

I like the suggestion of repeating the test with the engine running. If the charging and oil pressure indicators go off when the engine starts just set the parking brake and watch that light. Or the gauge illumination lights. With the alternator running, the voltage regulator should do what its name implies: keep the voltage constant as the load varies.

 

[Cornishman]

Same

John
My phase II CSi does the same. I also assumed a poor earth behind the dash, but if three cars do the same, then I think it is a characteristic of model.

Watch the fuel guage carefully and turn on the lights, mine moves slightly so I am interested if yours does the same.

C

 

[adawil2002]

My series 1 CSi, Athena, does not have any electrical issues like the ones discussed in this thread.

On my 2002Tii, Vern, when I turn on the turn signals the gas guage moves. I have added auxillary 'Y' ground to the dash too. All my grounds are clean on the car.

 

[Arde]

Don, Arde, Thanks - good tips. The problem is , though, that the fault (if it is one) disappears because, when you start the engine, the lights go out completely, naturally! I am still left wondering if this is then a hidden fault - hence the paranoia. The idea of a groundless relay is appealing - will make enquiries about these.
.

Yes, you might have to use another indicator light like Jay suggests or disconnect the pressure sensor. The rumors about groundless relays are groundless. All circuits have grounds even airplane electronics are grounded. I have used optical couplers for isolation but that is only useful if you have separate power supply domains. Coupes have a single battery and single rail as far as I know...

 

[sfdon]

The new relays use filaments as grounds in the turn signal bulbs at the corners not the same ground connector as the dash lights. The ground wire at the relay connector is not used at all.

 

[jvrenaudon]

Paranoia

Thanks to all for their tips and comments and to Jay, in particular, for the reassuring technical explanation. Cornishman - I will let you know about the fuel gauge effect once I get it working again. Andrew - yes, I think I will install an auxiliary earth to the dashboard chassis and I will follow up on the groundless relay. Best wishes to all. John.

 

[jvrenaudon]

OK - just one last thing here. At the back of the speedometer is a static double male spade terminal - an integral part of the dashboard pressing. On three cars I have examined only one of the tangs is used - this takes the earths from the adjacent instruments. The other one is left unused. The dashboard chassis would appear to rely entirely upon contact from the long 4mm(?) back fixing bolts for an earth contact. Wiring this spare tang to earth on the "A" post appeared to work but, in bright sunlight, hard to say. I will still persist with the new-fangled relay which I have on order. Best, John. PS does anyone have a wiper motor to sell or swap for a sunshine roof Ducelier motor, gearbox, screw, motion block and other stuff? Also have a couple of working window motors. J.