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skrufy September 21st, 2013 01:16 PM

Dip Beam headlights stay on....
Gents and Electric Gurus.....

A search of the Forums didn't find this problem, or I didn't used the rights words for the search.... I am pretty new to the 110s, but have had my '95 D1 since new, and have had 911s for the past-gasp!- 40 years now.:eek:

'87 110, 300Tdi: After driving last night in the rain, the low beams stayed on, and on, and on.
Has been the rainiest summer in 25+ years here in the mountains of eastern Arizona, so nothing unusual with driving in the rain lately.

The low/dip beams stayed on after turning the headlight switch off, and the ignition off/key out. Had to pull the R/L low beam fuses to kill the light so that I wouldn't kill the battery overnight. Made a couple of stops after this started, so I had to pull the fuses then as well.

High beam lights function as advertised, all other stop turn, running lights are a-ok. This 110 was imported into the US in the summer of 2012 from the UK. The high beam lights where wired into two big driving lights mounted on the brush bar. In addition, there are 4 more driving lights up on the roof rack that are selectable via a small switch on the right side of the steering column, available only when the high beams are on. At idle RPM, turning on all these lights really drags the alternator/RPM down, which tells me another problem for another day is to get a bigger amp alternator..... The big threat around here at night are the elk that like to feed on the sides of the roads, so all the aircraft grade landing lights are awesome, and way illegal, but hey, this is rural Az where we carry lots of guns... (for the faint hearted anti-gunners out there, we do have mountain lions, wolves, and bears here- never go into the forest w/o weapons... but I digress- sorry..).

In addition, I towed trailer yesterday for the first time with the electric harness for the trailer connected. I bought a AB Brit/US wiring harness adapter- essentially a 7 wire harness into the needed 4 wire for US trailers. Installed that 4-5 days ago. Similar to the one I installed on my '95 D1 years ago.

I don't think the trailer harness has anything to do with this problem. All trailer light functions were ok.

I didn't check to see if the low beams stayed on when the high beams were switched on. Will do that in a little bit after I post this...

From other headlight threads, it looks like the head light switch is a know weakness, as all of the juice comes thru the headlight switch. I do think I have relays for all the driving lights/high beams- will check and confirm- so that the full amps for those lights shouldn't be an extra issue....

So the headlight switch is known to be a weak link. Which switch are we talking about? - the basic small forward one on the left of the steering column "OFF/Running/Lights On" or
the High/Low Beam/Turn Signal/Horn Switch? I don't want to order the wrong one if mine is bad.....

I have the big LR factory D90/110/130 manual. The circuit diagram is a bit confusing. Besides the fuses, is there another factory headlight relay located on the back side of the fuse panel, or somewhere else??

As usual, thanks for the help/advise.

If we want to find a real under-engineered POS headlight/turnsignal switch, look no further than the Porsche 911, 1965 thru at least early '89. Hopefully, the Germans fixed those in the later cars- Don't know those very well....


PaulMc September 22nd, 2013 12:58 PM

It sounds like the Dim-Dip unit has failed.

Dim-Dip was a stupid idea fitted to UK Land Rovers in the 80's right through to the early 2000's.

The earlier version of Dim-Dip, which my 110 had (now removed), used an electronic unit, fitted to the bulkhead behind the instrument binnacle, to power the dipped beams at 30% (I think), when the engine was running and sidelights only were switched on.

When the Dim-Dip unit inevitably fails, the dipped beams stay on, even with the main lighting switch off.

The Dim-Dip unit is connected by a 6-way connector which, if un-plugged, returns the lighting circuit to normal.

The Dim-Dip unit looks like this -

And this, when fitted behind the instrument binnacle -


navydevildoc September 22nd, 2013 03:05 PM

Bingo. Dip-Dim unit has failed. Unplug it. Strange kind-of-like-daytime-running-lights-but-not-really.

skrufy September 22nd, 2013 03:22 PM

Thanks guys-

I'll go out and start pulling things apart to find that Dip-Dim unit. The wiring diagrams I have don't show that unit, and/or I didn't know what I was looking at with some electrical symbol..... Chasing queertrons around the vehicle wiring harness while trying to fix some electrical problem is my least favorite automotive task. Typical engineers- the ones that design it aren't the ones who have to fix it.....

Minor correction to my earlier post- when my high beams are on, the headlights do switch to high, plus the two brush bar driving lights go on. When the roof rack lights are on, the result is 8 highbeams during the way forward into daylight. I have no problems getting on coming traffic to dip theirs....


skrufy September 23rd, 2013 12:24 AM

Awesome! problem solved!

Many, many thanks to Paul in Kent, UK and to Neill out in San Diego.

The Dip-dim box was definitely the evil culprit. I never would have figured that out- it does show up on my circuit diagrams, but on another page as an accessory or option- with no explanation as to it's function or failure modes.

While I had the binnacle loose, I noted extra wires and connectors behind it that lead to ??? to do what? and I haven't figured out yet what two extra fuses do in a holder to the left of the main fuse panel:confused- obviously add ons by somebody......

Information so readily shared by the members of the Defender Forums is what makes this site so important and useful. IMHO, the only questions that are stupid are the ones you don't ask....

Thanks again:flowers:


PaulMc September 23rd, 2013 05:35 AM


Originally Posted by skrufy (Post 469562)

The Dip-dim box was definitely the evil culprit. I never would have figured that out- it does show up on my circuit diagrams, but on another page as an accessory or option- with no explanation as to it's function or failure modes.

Dim-Dip was a UK only thing, that didn't comply with European lighting regulations and was dropped (eventually); but, not before Land Rover had updated the later models, by replacing the unit you have, with a Pink relay behind the instruments and a big Gold resistor behind the RH inner wing panel.

The later type is a little trickier to disable, as it requires by-passing at the relay mounting base.

Land Rover, very thoughtfully, sell a 'by-pass relay' (YWZ10003L) to do this; but you only need a short wire with a couple of male terminals, to bridge across two of the terminals in the relay base.


Originally Posted by skrufy (Post 469562)

While I had the binnacle loose, I noted extra wires and connectors behind it that lead to ??? to do what? and I haven't figured out yet what two extra fuses do in a holder to the left of the main fuse panel:confused- obviously add ons by somebody......

On a Defender of this age, there are a few unused wires behind the instrument binnacle, these are for the optional equipment that was available at the time.

Brown wires are unfused permanent lives

White wires are unfused ignition-switched lives

Green wires are fused ignition-switched lives

Purple wires are fused permanent lives

Red/White trace wires are instrument illumination

Black wires are earth

The 2-way fuse carrier (PRC3737) clipped to the main fuse board, is used for rear window washer & wiper circuits, as well as other optional circuits.

I've added a couple of them on my 110, for the ICE system and additional lighting -


skrufy September 23rd, 2013 11:27 AM


Thanks again for the info and this interesting bit of LR 110 history. I do have the rear window wiper and heater- I will play with those to confirm those two extra fuses, and then label them.
Only makes sense to have a universal wiring harness to fit all markets/laws around the world, hence the unused wires/connectors.... Found a UK penny tucked away under some of the wires- polished it up so that Her Majesty looks pretty again. Will keep it in the 110. Over here, you don't want your image to be on any of the currency, as only dead Presidents, etc can have their images so enshrined...

Unused wires: telephone cable over here- the home use stuff, comes with 4 wires, when only two are needed to connect a phone to a phone jack in the wall. Any US readers know why?? Well, in 1964? Bell Telephone came out with their new and exciting Princess Phone, it was so exciting (or so the marketing guys said..) to pick up the phone, and the dial would light up at night! Who-da thunk it? When was the last time you say a Princess Phone in a museum someplace? Yep, the extra two wires were to power the light bulb, which means there are millions of miles of unused phone wire here in the US, and they still make it that way.... Of course, you can hook up two different phonelines given the 4 wires, but with todays computers and data transfers, the two phone lines put out just enough interference as to cause modems to go nuts- or so a Phone Tech guy told me.

Unused wires Part Deuce: in a former life, I was a military aviator.. I had been flying in a big desert exercise out in Nevada. My mission for the morning was done- I parked my jet, handed it back to the crew chief, and was walking back to the ramp. As I took a short cut thru long lines of parked fighters, I stopped to look at an F-4E that had most of the panels open. The F4 was flown by the US Navy, USAF, the RAF, the Luftwaffe, and many other US Allies. Aircraft wires are so numerous that they can't color code them- the mylar coated aircraft grade wires are all white, with a 8-10 digit number embossed on it every 6-8 inches. I commented to this F-4E's Crew Chief about the wires I saw- numerous wire bundles- the size of your wrist, that were cut off, sealed, and tied off. He said each jet probably had 2 miles of unused wire that got carried around each flight- so many modifications had been done over the years, that it was cheaper to just add more wire vs trying to remove the old wires- I wonder what it cost each year to haul that around:confused ?? Not that it really mattered with the F4 anyway- that jet was living proof "That with enough thrust, you can make a Brick Fly":grin..... None of us single seat, single engine guys:cool: could figure out what the extra engine was for, or what that other guy did in the back seat!!


akrockhound September 25th, 2013 06:43 PM

timely thread
I am in the middle of replacing all my switches on the steering column. Was looking behind my instrument cluster last night and wondered what that block box (dip/dim) was and why it was unplugged. Unfortunately I plugged it back in (thinking I was doing something right for a change) before closing everything up. So I guess I will be going back in there tonight to unplug that baby.

skrufy September 26th, 2013 02:02 AM


IMHO you don't need to open up the can of worms/bannicle and unplug it- as long as the dip beams work ok- just go with it = at dusk, you can run with the marker lights on, along with the 30% illumination on the dim/low beams of the headlights.... this will give the basic illumination/ recognition that your vehicle is present w/o having to turn on the higher powered headlights. If the dip beams fail in the future and you can't turn them off as was in my case, then disconnect the the dip-beam unit. haven't had my D1 binnacle apart for a while, but I know it's more of a PITA than the quick 4 screws of the Defenders....

As screwed up as Porsche is with their design of the hi/low/turn signal all-in-one lever on the 911s, they solved the dip-beam issue by merely adding a small 12volt marker light socket below the main hi/low halogen bulb- at least that's how it is on the Hella European H4 lights that many of us run. As with the LR system, this Hella method illuminates the reflector, giving larger illumination than the small bulb alone. These are wired into the regular position lights all around the 911s. Cheap idea/works great.

Thanks to all for the inputs- ya done good for some future readers....:thumb:


Ashek October 31st, 2013 06:56 PM

Hah, it has saved me a lot of confusing lurking. Had the opposite problem (headlight wouldnt turn on) and now they wont come off... go figure :)

Skrufy, I think we have the same truck: 87 110 with a 300tdi from the UK :)
A previous owner had solved the horrible design of sending all the headlight juice through the switch by putting in three relays near the front left headlamp.

The normal power circuits just operate those relays, which in turn are fused power through heavy guage wires going direct from battery. One for Highbeam, one Lowbeam, one for fog lamps. Works fairly well when i replaced that relay.

And then today, with this Thunderstorm in Tennesse, low beams stay on. No worries, i have a bat cutoff, but annoying as hell. NOT looking forward to opening up the dash to try to find the little SOB and unplug it.

Another bit of info on the whole dim dip language thing.

Main lamp = highbeam
Dipped beam = low beam
Dim = lowered power (through a resistor).. think of a dimmer, same idea.
Took me forever to figure out what dim-dip meant.

Also, heres a wiring diagram ive been working off of, its been pretty accurate so far, but some things are obviously newer/different:

wiring diagrams for 97 model year:

connectors - pinouts - locations, etc:

that legion site is a goldmine too, but its from colombia.. go figure :)

skrufy November 1st, 2013 01:01 AM


First disconnect the battery so you don't hit a hot connector and fry something behind the dash...... ask me how I know- not the 110, but another truck in the past...

Opening up the dash to disconnect the dim-dip relay is about a 5 minute job- 2 screws on each end of the instrument panel. Gently pull out the instrument panel- no need to try and disconnect the speedo cable. The relay is mounted just under the top surface of the dash forward of the steering wheel. It appears to be mounted with some double stick foam tape.

In the pix that Paul sent of the relay, he had to work from an awkward position, low and to the left, rotating his camera to try and capture the dim-dip relay. If you rotate this pix 90d clockwise, it then more accurately presents the location if the relay. In the pix, the metal bar is one of the structural supports for the steering column.

Piece of cake- max of 8 minutes, maybe 10 with a few swigs of beer....:thumb:

Will look at the circuit diagrams a bit later- thank you.


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