Discovery 2 | Blinking brake lights

Adios amigos, or two of them anyway...

The image above is what greeted me upon acquiring my first Land Rover, a 1999 TD5 Discovery 2. Given the lack of documentation on the problems I uncovered, this piece will hopefully provide some usefulness to fellow Disco owners.

The photo shows the dashboard lights after turning on the ignition. Two of the amigos - Traction Control and ABS - were illuminated along with the central diff lock light (even though this example doesn't have the linkage fitted) and the ACE warning light. We later discovered that the brake lights and the reversing lights weren't working, although a quick test revealed that the bulbs themselves were fine, so the issue had to lie with the wiring.

Opening up the fuse box under the steering wheel initially revealed what we thought was the cause - there was no fuse in slot F25, which controls the brake and reversing lights. Due to a lack of spare 15-amp fuses in the main box, we instead swapped a 25-amp fuse from the air con unit as a temporary replacement. For a while, this appeared to fix the issue, and the rear lights worked as expected.

Not a clean solution, but it seemed to do the trick...for a few hours

Then less than a day later, the fuse blew again, ironically while out buying a new fuse set. This time I replaced the blown fuse with the correct 15-amp unit, which blew immediately upon turning the ignition. I tried four different fuses at different ratings, all of which blew in a similar manner. Clearly the issue was more serious than initially suspected.

The Solution

There was a fair bit of dilly-dallying after this, but I'll cut right to the chase and explain the problem. Testing the resistance of the fuse slot itself gather rather confusing results. Sometimes the readings were perfectly normal (around 3 ohms), other times the reader maxed out to imply a short circuit. At this point, the issue was pointing to the brake light switch or the reversing light switch. Not wishing to remove the console to get at the latter, we checked underneath the car to investigate the wire for the reversing light switch located just behind the main chassis bar on the passenger side...

Approximate location of the wire behind the gearbox

...bingo! The wire had chafed on the chassis and become exposed, shorting out on the chassis rail. This explains the inconsistent resistance readings and fuse blowing. We then wrapped a piece of black tape around the exposed area, replaced the fuse and presto! The lights worked, the fuse held out and most of the lights were extinguished (except for the ACE light, but that's a problem for another time).

Conclusion

In the grand scheme of things, this wasn't exactly a major issue, but certainly a niggling one. I suspect that other Disco owners may encounter different issues, but I hope this piece has at least enlightened you to a possible solution to brake light issues. It is, however, a temporary fix. I will update this blog when we implement a more permanent solution.