Wiring fuse box

[Althulas]

I have made a silly mistake of not disconnecting my battery whilede wiring the added wires I connected to my side lights for my old angel eyes and ended up making a short resulting with a load of smoke from the wiring loom on the near side to the fuse box, the tape around the loom had burnet through midway up and a load of smoke came out the fuse box when I took the cover off.

Striping back the tape around the loom to the fuse box there is one wire completely shred of it's insulation and a few other singed wires. The partially damaged wires I have cut out the bad sections out and spliced new sections in. The wire that has shredded it's insulation looks like its the pink/grey wire to the left side light, I've tried to bridge this with new wire but still have no power going to the left side light or rear light for that matter. I have also checked the sidelight fuses which are o.k

Looks like I will have to take the headlight out and strip down the rest of the outer sheaf and to asses any further damage but I think the problem will be found in the fuse box.

Anyone had to take the fuse box out before as I would like to know how the wires from the loom are connected inside and are there any relays associated with the side lights?

The rest of the car electrics are functioning fine the only consolation for me as it could of been worse if I hadn't of look up when I did and noticed the smoking from the harness.

 

[GazHyde]

Is this of any use? https://zroadster.org/resources/1999-z3-z3m-electrical-troubleshooting-manual.13/

Don't have a clue with car electrics

 

[Brian4]

Not much help I know but there are no relays in the side light circuit.
Do the right side lights work?
Have you checked both fuse 33 and 37

Checking the wiring diag if you had shorted it should have blown the fuse so it could be a damaged wire in the light switch.

 

[Althulas]

The right rear light comes on and the right front did last night so I don't think it could be the switch but it was stiff to pull back following the incident. I did take the light switch out. There were no fried wire going to it and no burnt smell from the unit, while I was there I changed the light switch bulb

I'll have to bite the bullet tomorrow and open up the fuse box and take a look if no one has done it before. I will check that PDF out later too.

 

[Althulas]

The new earth I wired into the bundle in the fuse box is good just the power issue to resolve. I have traced the grey/violet wire back into the fuse box which connects to another two other grey/violet and a grey/black wire which according to the wiring diagram is for the tail lights https://zroadster.org/resources/1999-z3-z3m-electrical-troubleshooting-manual.13/ page 217.

I have replaced the grey/violet wire from the front side light as its quite singed in places leading up to the bunch in the fuse box. The bunch of wires it connects to in the fuse box look unscaved so hopefully this was the fix I was hoping for.

What a frustrating day after having the fuse box apart again. I still have no power to the near side lights. I know the earth is good but the trail of the grey/violet wire still requires further investigation. As I hope you can see I was connecting to quality wire.

After the initial incident the light switch was stuck and needed a yank to free it up to work the lights. Is it possible that the light switch could be faulty and only passing power to the right sided lights??

 

[oldcarman]

Yes, I think you're right. Obviously the switch took quite a jolt and something inside, likely a contact or two partially welded themselves together which is why it was so difficult to turn on. You're very fortunate that the whole loom didn't fire up. You'll never make that mistake again I'm sure. Your tester will be your friend in solving this but remember not to use an analogue tester but a digital only. A new or used switch is likely as you already suspect. Good luck JIM

 

[Althulas]

I was thinking along that line but the near rear brake light I would have thought still functioned. any tips on how to use the multimeter to test the switch?

 

[oldcarman]

Pretty simple, set to 12v and make sure you have a good ground spot for the negative cable, check each contact being careful not to bridge any or you could get erratic readings. You can use this on both ends of the wire harness to trace a dead wire. Just remember that to complete a circuit the flow is dependant on a good ground. JIM

 

[Brian4]

Just a thought are you sure the brake light worked before you had these probs? The plastic that the bulb holders plug into in the rear lights has been known to crack and not allow the contacts on the bulb holder to make fully.
I will bring some pages from the wiring diag tomorrow.

 

[Althulas]

I feel a bit of an ass in my haste whipping out the back light i must of either knocked the brake light bulb out so it's either in the housing or in the boot somewhere, so I have brake lights just the rear and front side light to sort out. I'm going to try a new light switch first before taking the dashboard apart as the wires to the switch appear to be all intact.

 

[t-tony]

I think Jim is correct in thinking that the switch overheated during the short circuit and probably melted the internals of the switch. Best to replace it if you can. Try Andy and see if the has one.

Tony.

 

[oldcarman]

I feel a bit of an ass in my haste whipping out the back light i must of either knocked the brake light bulb out so it's either in the housing or in the boot somewhere, so I have brake lights just the rear and front side light to sort out. I'm going to try a new light switch first before taking the dashboard apart as the wires to the switch appear to be all intact.

Don't feel bad, we've all been there! Sometimes it's the obvious that are the easiest details to miss. Stick with it and all will work out eventually. JIM

 

[Althulas]

After the cruise today I removed the light switch out and disassembled it. Quite a mess as you can see, I tried to clean up the melted bits to make the sprung contacts work as seen in the second photo but a wasted effort as there still is no power to the front side light or rear light.

Inspecting the wires to the light switch in more detail in the light of day I found a few of the wires for the first 4 inches or so lightly bonded together separating them pulled off a bit of the outer sheaf

I'm still going to get a replacement switch as it taken quite a beating.

Can anyone explain how to use a multimeter on where and which electrodes do I place to check the wires leading to the switch for the fuse wire ... can I check for power or a break in the wire? The brake and side light for the same investigation and would I need to have the car battery while doing these test? Apologies for my ignorance in this but trying to learn and its the last checks before I will have to take the dash board apart. I have aske on .net as well as Southernboy has been helpful as well.

No 1 pin is the left front side light Grey/violet, No 7 is the fuse wire white/red and No 8 is the left rear brake light grey/black but there has to be power in the grey/black wire as the right rear light works. No12 grey/green will be the front side light if I'm following that diagram correctly.

 

[oldcarman]

The easiest tester to use looks like a screwdriver with a pointed tip and a cable coming out of the handle. Don't use one with a bulb but rather one with an LED. The cable coming from the handle will most likely have an alligator clip and is your ground wire. The point can be inserted anywhere along the wire you are testing without any danger or problems. Just connect your ground to a solid source and work your way through the wires individually and up to the contact. The light will come on if 12v are present and if it doesn't light you've found a problem. Personally I prefer this method for simply testing for power as opposed to the multi which will give many different types of measurements and takes experience to know what settings you need for the different operations which is why I use the KISS method and the other type tester first. Hope this helps and here the testers I mentioned are about £5 for a heavy duty one! Check every wire even if the lights are working and particularly any with even a hint of blistering anywhere. They are trouble waiting to happen. Good luck and hopefully if I've provided faulty info someone more savvy will correct me. JIM

 

[Althulas]

Good news and good news today I think I bought me a little gadget that plugs into your fuse sockets to give you a reading, so I have power now confirmed going to fuse 33 left side light. I also bought me one of those testers that Jim suggested. I tested the wires going to the light switch some of them work with the light switch in position 0 i.e. the fuse wire. Pulling the switch to position 1 I get a 'light up' from the grey/green wire i.e. right side light and no 'light up' from the grey/violet wire i.e. left side light. I get 'light ups' from the rest of the wires in various setting of the light switch. With the switch position at 0 there is no 'light up' to either the ride side or left side light but a response for the right side light at position 1 so I think I could rationalise and conclude that the light switch is knackered, kaput, the offending culprit well me the culprit

Just waiting for a switch replacement and will update.

 

[oldcarman]

Something else I thought of this morning is to check your high beam light bulb on the dash to verify you didn't blow anything in the column. Glad things are coming together. JIM

 

[Brian4]

Might be worth contacting Sopers to see the price of a new one. The switches are known to wear over time.

$44 from this site so should be avail in the UK

http://www.turnermotorsport.com/p-24360-genuine-bmw-light-switch-61318353506.aspx

Ps here's the part number 61318353506

 

[Althulas]

No problems withe main lights Jim and the yellow wire/ high beam shows continuity.... learning the jargon as well I forgot to add that Lee has posted me a light switch today. Just got to remind myself to check the grey/violet wire from the fuse to the light fitting in the morning.

 

[oldcarman]

No problems withe main lights Jim and the yellow wire/ high beam shows continuity.... learning the jargon as well I forgot to add that Lee has posted me a light switch today. Just got to remind myself to check the grey/violet wire from the fuse to the light fitting in the morning.

Just wanted to make sure all bases are covered so nothing else goes up in smoke after you put everything back together. JIM

 

[t-tony]

When I'm doing anything electrical which may/may not be a bit on the risky side I only "connect" the battery earth lead by VERY lightly clamping it to the side of the battery post so that in the event of " Bloody hell it's smoking" you can release the terminal instantly.

Tony.