Lighting Failure

UK forum for general and technical discussion about the Z3 roadster
Post Reply
stahlgrau_hants
Joined: Mon 04 Jan, 2016 17:29
Posts: 8

  Z3 roadster 2.8

Lighting Failure

Post by stahlgrau_hants »

A couple of weeks ago, literally a couple of days after an MOT, I was driving and when indicating the indicators went at double speed. Fortunately I had a spare bulb on me, so I replaced the failed bulb at offside rear. However, when I went to check the new bulb, putting on the right indicator, nothing happened at all. Nothing flashed or clicked, nothing. I tried the left indicator. Nothing. I tried the hazard warning lights. Nothing. I then studied the fusebox diagram and pulled a few fuses. Looking at them, they all seemed to be intact and not blown.

I then decided to order a new flasher relay, which arrived today. Pulling apart the old relay, there was a very slight burnt electronic smell, but no visible issue. Nevertheless, new (second hand) flasher relay installed, and still no indicators or hazards. After another check in the fusebox, pulling and reinserting one of the fuses made the hazards switch on, even though they were switched off. Switching them on and off at the switch inside the car corrected this. However, on checking all the indicators again, offside rear wasn't working despite the new bulb. So, I removed the assembly and looked at the new bulb, and it looked fine. I then checked the other lights. Rear lights worked fine, and brake lights worked fine. However, offside reversing light and offside rear fog light were also not working, whilst nearside ones were.

As such, I have a lighting failure specifically affecting three out of five lamps on the offside rear. Does anybody have any ideas?
User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 10:35
Posts: 10133

  Z3 roadster 1.9
Location: Cheshire

Re: Lighting Failure

Post by Robert T »

Time to study the wiring diagrams. Look for ETM or Electronic Troubleshooting Manual in the knowledgebase. There's an art to reading them, but it will tell you which wires and which fuses. I'd still place money on a fuse.

Cheers R.

Sent from my SM-G960F using Tapatalk

Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image
stahlgrau_hants
Joined: Mon 04 Jan, 2016 17:29
Posts: 8

  Z3 roadster 2.8

Re: Lighting Failure

Post by stahlgrau_hants »

I did some more investigation today. After inspecting all fuses in the fusebox closely, Fuse 34 had a hairline fracture that meant it was passing current intermittently. I've replaced this fuse.

Compared with last night, the offside reversing light is now working, but offside rear indicator and offside rear fog light are still not working. So, another component replaced, but a peculiar and partial change.

The other week, my nearside tail light bulb failed and I replaced it, but no issues at the time. So, in the past month, two bulbs, a fuse and a relay have been replaced. Hmm. Of course, I've not been able to check all the wiring. One thing I have observed is that all the five lamps in the cluster share a common neutral, so can't be an issue with that. So, it's something in the positive connection somewhere between the fuse and the offside rear cluster.
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2076

  Z3 roadster 2.8
Location: Daglan, France

Re: Lighting Failure

Post by Mike Fishwick »

You cannot fault-find on the internet! Make yourself a 21 watt test lamp and check the current tracks of the tail lamp unit for power. Then follow the side with no power until you find the answer . . .
A Z3 is not just for Christmas - it's for life!
Post Reply