Electrical niggles, help please

[swindler]

OK going mad here:

1. Most important:

tail lights and rear number plate lights are out on both sides. Have replaced all bulbs and tried different light units. Front side and main beams fine, brake lights fine. The check control does signal a fault.

Any clues?

2. 6 button obc has never worked- bought a replacement second hand which seller swore worked 100- have plugged in. It glows orange with no readout at all, but then sometimes has random crazy digits then goes off...

Anyone helping me solve this will be rewarded with lashings of beer or rides in the car...

There is no radio in the car at the moment, I have the original BM item but someone has butchered the loom with a late connector...

Mark

[Brianmoooore]

LH tail light is hard wired to the LH front sidelight, and the RH tail light is hard wired to the RH front sidelight, except for the connectors to the bulb failure module in the boot on the LH side, so it's likely your fault is there.
Number plate lights also go this module, but so do the brake lights.
Can't offer much advice on the OBC, other than it takes most of its feeds directly from the instrument cluster. Another duff OBC would seem the most likely.
Radio loom is quite short, and plugs into the accessories socket behind the glovebox.
There are aftermarket looms available which have a modern ISO connector on the radio end.

[swindler]

Thanks, where in boot is bulb failure module? Just to confirm rear fogs working.

Think you're right on OBC, may just bite the bullet and give a dealer 80 notes for a new one...
M

[Brianmoooore]

Bulb failure module is fairly well hidden, but is almost touching the aerial mast.
If you're changing the OBC, go for the 13 button version. They're always coming up for sale.

[swindler]

I'll have a nosey tomorrow. Though my aerial is roof mounted. And it's not a touring ;)

would a 13 button need any more sensors tho?

[swindler]

Oh and smart pic by the way, tourings look so good dirty, like some 911s...

[swindler]

what do you know, you were right. I swapped it with another one from a donor car and the lights came on!! The check control went off for the rear lights but is still showing a red light for the number plate lights even though these are on- any ideas?

But importantly I have lights and am MoTable so I guess I owe you a pint.

[Brianmoooore]

First thought on the number plate lights was that someone had fitted a 5W bulb in one instead of a 10W, but on second thoughts, they are supposed to be 5W!
Do the number plate lamps flicker at all, if you thump the back panel near them? Are they both of equal brightness? One only has to go out or dim for a fraction of a second for the check light to come on and stay on, until reset by switching off the ignition.

[swindler]

Had the car out again and by the time got home the tail lights (both) and one number plate light have failed again

Any advice?

[Brianmoooore]

I didn't think that the problem was the actual lamp failure module earlier, but you changed it anyway, and seemed happy! The problem is much more likely to be something up with one of the two plugs that go onto it. These are the only joints in the wires, common to both circuits, but not common to the front sidelights.

[swindler]

Yea I see what you mean. I'll check the contacts etc. Am I right these wires run under the carpet? Could they be damaged under there over the years?

M

[Brianmoooore]

Wires should be in a recess along the LH sill, although is a little more vulnerable where it comes up over the rear seat pan.

[swindler]

Brian,

Have had the car out again. Fuses 22+23 fine (front lights all ok too)

NSR lights all ok
OSR tail light and number plate light out

Hazards, brake lights ok (so OSR light unit works)

Do you know the colour of the wire that runs a) to the lampencontrolunit from the fusebox? and b) from the unit to the bulbs?

Thanks

Mark

NEED TO GET MOTd ASAP

[Brianmoooore]

OSR: Grey/white from switch to bulb module. Grey/green from bulb module to tail light.
Number plate lights: Grey/red from switch. Plain grey and grey/black from bulb module to number plate lamps.

[swindler]

Magic. I'm right in thinking this must be a wire/connection thing now...?

[Brianmoooore]

Pull the 'in' plug out of the lamp check module, and use a bulb to check for power at the appropriate wires.

[swindler]

I have a short somewhere that will blow a 7.5A but not a 30 A fuse

It's blowing the check control units, I have gone through three now...

Thought I'd found the problem twice- 1st a screw on the number plate light touching the connector? NO
slight bare wire to OS number plate lamp, NO (but good to have found it I guess)

Now the other side has blown!!! And the first side is working.
Doesn't always blow straight away (do you think that it is a 'loose' short circuit, only touching on bumps when driving say?), hence has cost me a MoT retest

I despair...

[Brianmoooore]

If it's blowing the check control bulb filament monitor module, then the short(s) are narrowed down to the wiring in the LH side of the boot and across the back panel.
The cab that I've just bought from someone on here has had a towbar at some point, and I've found the wiring to the towbar socket just cut straight through, hidden in the boot. All seven wires of the cable are bare at the cut end, and in imminent danger of shorting to each other and/or earth. Anything similar on your car?

[swindler]

It's not got a tow bar... (unlike my other e30 but that's a leaking petrol tank story)

Just had five pints of Guiness so am feeling much more relaxed.

From what you have said, because it's blowing the lampenkontrolunits/bulb failure module then the problem's in the boot wiring. I've scoured this for problems unsucessfully, so I'm actually going to replace the lot from a breaker. Incidentally, when I put the 30A fuse in and turn the lights on , the wires smoke under the boot catch. Is this just the current making it hot or would you say the short is there? Doesn't help that the whole area is smothered in clear waxoyl.........
M

[Brianmoooore]

Putting a 30A fuse in wasn't your best idea! You will definitely have damaged the entire body wiring loom of the whole car.
The relevant wires in the loom towards the front of the car will have heated to the point of melting and burning their insulation, especially where they are closely bunched with other cables, and possibly have melted into those cables as well.
Hopefully the damage won't be severe enough to cause future problems!!
The wires smoking under the boot catch may be the site of the problem, but it proves, at least, that the fault is between here and the rear right lamp cluster.
P.S: My cab doesn't have a towbar either - if it had, the wiring would be fine. It has had a towbar at sometime in the past, which has been very badly removed.

[swindler]

Brian,

Thanks, and sorry for being a fool wiht the 30A fuse, fingers crossed it hasn't blown the whole thing-seems to be ok

I think I found the short successfully in the boot, have rebound all the boot loom- I did this fairly tightly with insulation tape- is that sound?

Anyway, now the right hand indicators repeat very fast (as though a bulb has gone-but they haven't)

Any clues this time???

Thanks

[Brianmoooore]

Anyway, now the right hand indicators repeat very fast (as though a bulb has gone-but they haven't)

Any clues this time???

Thanks

It's a legal requirement that indicator systems give a warning that a main bulb has failed, and this is usualy achieved by by designing the flasher module to flash faster with the reduced current when a bulb has failed.
Since yours work properly on one side, the module is working, and it thinks a bulb has failed.
For it to think this, a reduced current must be flowing.
If all the bulbs are working, there must be a poor connection, causing one to be working at reduced brightness.
Turn the hazards on, so that you can compare the two sides at the same time.
Prime suspect will be the front indicator, as these are not designed to be waterproof. The lamp holder won't corrode, but cheap bulbs will.

[swindler]

Got it, will investigate. You were right about the OBC, btw...

[swindler]

Thanks Brian, right again. Quick brush and vaseline of bulb has sorted.

Refitted the original Blaupunkt Bavaria C today too, fancy another challenge?-

the left hand speakers (front and rear) are not working. Car has balance switch on dash (makes no difference-and didn't with previous modern stereo).
Used to have Premium speakers, which I still have, but these replaced with modern pair. I may put back.

I took out the ISO wiring when fitting the radio. Any thoughts as to getting the left hand speakers working?

Thanks, I really owe you

Mark

[swindler]

Brian?
Anyone else know about stereo wiring?

[Brianmoooore]

Swap over the left and right speaker connections at the radio.
Does the problem move to the other side, or stay where it is?

[Globulator]

If it is like my cab you need to completely rewire the speaker wires - front and back - the old system used a common earth system with a 'balancer' in the front.

Not compatible with modern radios as they want to energise both ends of the wire!

If you are lucky there are built in wires going to the door triangle pads on the door so you can fit pop tweeters there too. Takes a bit of finding though - took me about 4 weeks of working out in the rain evenings to rewire mine.

[swindler]

Brian, I will investigate at the weekend.

Globulator, I have replaced the modern stereo with a Blaupunkt Bavaria C reverse that was originally in the car. It has the tweeters in from new, and the one on the right hand side is working along with the right hand rear and footwell speakers. All three on the left are silent....
any thoughts?
mark