1990 80 Series Landcruiser headlight problem

Submitted: Thursday, Jan 30, 2014 at 21:15
ThreadID: 106018 Views:16224 Replies:7 FollowUps:10
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Hi, my son recently bought a 80 series Cruiser and the headlights don't work. When you put the headlight switch on, the parkers work but not the headlights(low or high beam). We have changed the headlight relay in the engine bay fuse box and while we were at it we replaced all fuses in that fuse box and also in the dash fuse box as well.

We put another headlight/indicator combination switch in as well (2nd hand , not new) but still no luck. There is power to the two 15 amp fuses when the headlight switch is on. I have put a multimeter on the red/white wire from the combination switch connection under the steering collumn and to the harness connection near the washer bottle which goes to the headlight relay and the multimeter doesn't move which I assume means there is a break in that wire or the wire goes to something else under the dash which is causing it not to work.

I run another wire from one end of that wire to the other end, basically bypassing that wire and I can get the headlight to come on but when I put the high beam on the high beams don't work and the low beam goes out. I'm at a loss as to what else to try, is there something else under the dash that the headlight wire may go to first? Any help will be appreciated, I hope I've explained everything properly we have done so far to help with any suggestions.
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Reply By: neill - Thursday, Jan 30, 2014 at 21:23

Thursday, Jan 30, 2014 at 21:23
BTW, i forgot to mention it's a manual diesel with aftermarket Safari turbo.
AnswerID: 525429

Follow Up By: Brian 01 - Thursday, Jan 30, 2014 at 22:10

Thursday, Jan 30, 2014 at 22:10
Are you aware that the headlight switch operates in the negative wire?
Is the relay energising when you operate the switch?
If you run a temporary earth to the negative side of the relay, what happens?
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Follow Up By: Ozhumvee - Friday, Jan 31, 2014 at 08:01

Friday, Jan 31, 2014 at 08:01
Yep Toyota switches earth/ground which then activates a relay to switch the positive to the lights.
I found on a same year troopy that if the dash high beam indicator globe blew it took out the lot too. Check that before going any further as the 80 could be the same.
Peter
1996 Oka Motorhome

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Reply By: scruffy - Thursday, Jan 30, 2014 at 21:40

Thursday, Jan 30, 2014 at 21:40
Possibly the previous owner had HID lights fitted and on removal prior to sale the wiring got mixed up or a wire not connected. Suggest a trip to a good auto elec and tell him what you have found. Cheaper and less frustrating in the long run. Bob
AnswerID: 525430

Follow Up By: Kerry W (WA) - Friday, Jan 31, 2014 at 00:39

Friday, Jan 31, 2014 at 00:39
This year model was also prone to failure of the headlight circuit if the prev owner installed high power (100w90w) globes into the headlights. (I assume it is the 4 headlight model)
Not 100% sure what the exact problem was but some overload occurred - was expensive to rewire as the whole circuit needed replacing.
Kerry W (Qld)
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Reply By: Wayne's 60 - Friday, Jan 31, 2014 at 01:55

Friday, Jan 31, 2014 at 01:55
Hi Neill
We had issues with our lights - some sealed beam and some H4 running off relays.
Low beam worked, onto Hi beam all good, off Hi beam nothing - Very dark.
Short long story, dodgy earth.
Fixed by fitting a super loom ($200) and now running 90/130 & 150.
Cheers,
Wayne & Sally.
PS
Your multi metre will tell you there is power.
It won't tell you if your circuit has insufficient earthing.
W&S.
AnswerID: 525447

Reply By: get outmore - Friday, Jan 31, 2014 at 11:31

Friday, Jan 31, 2014 at 11:31
I was going to say headlight relay as it sounds just like it.
But youve bern there..
I would remove the cover and confirm the relay is functioning.
You can manually push the relay shut
AnswerID: 525471

Follow Up By: Brian 01 - Friday, Jan 31, 2014 at 11:43

Friday, Jan 31, 2014 at 11:43
I would have thought that the relay was functioning OK as he has power at the fuses which are downstream of the relay on that model.

The bit about bridging the length of the red/white wire making the headlights work has me confused, as that wire only controls the relay coil, and the wire would have to be OK for there to be power at the fuses.
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Follow Up By: neill - Friday, Jan 31, 2014 at 16:24

Friday, Jan 31, 2014 at 16:24
Hi Brian, That red/white wire doesn't have power through it, it's the negative wire from the relay to the combination switch.
If that wire was ok, when I put the multimeter on each end it should complete the circuit and show on the multimeter unless off course that wire goes to something else first. There is about 5 or 6 relays in the footwell on the drivers side i saw today in the gregory's workshop manual not sure what they are for yet.
Sorry guys, I haven't had a chance to look at the car since I posted as it's pouring rain here from the cyclone.
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Follow Up By: Brian 01 - Friday, Jan 31, 2014 at 16:58

Friday, Jan 31, 2014 at 16:58
I am aware of that Neill (see my earlier post).
My point is that if the left and right headlight fuses have 12v positive to them, then the headlight relay must be energised as they are downstream of the relay contacts and only get power when the relay is on.
The only way the relay can be energised is by there being an earth at the -ve terminal of the relay.
Of course this doesn't in itself rule out a broken r/w wire with the relay end to earth, but you mentioned that the fuses have power only when the headlight switch is on.
This would tend to preclude any possibility of there being a break or fault in that r/w wire.

Why are you then not getting a continuity test on it?

One possibility for this is that some models had a diode on that r/w wire for the rear fog light, and you may just be testing across that in the blocking direction.
Try reversing the test leads and see if you get continuity, or even put the meter in diode test mode.

Why then do you not get high beam?
I assume the fuses are OK.
With power to the fuses, if you apply an earth to the individual H & L beam -ve wires, what happens?
What happens if you operate the headlight flash mode on the switch?
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FollowupID: 807429

Follow Up By: Member - Frank P (NSW) - Friday, Jan 31, 2014 at 17:07

Friday, Jan 31, 2014 at 17:07
A bit off topic, but since switching the -ve has been mentioned here, why is it done?

What are the advantages over the more conventional (well, it used to be!) switched positive?

Cheers
FrankP

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Follow Up By: Brian 01 - Friday, Jan 31, 2014 at 17:20

Friday, Jan 31, 2014 at 17:20
It is generally done where computers are concerned so that shorting out the interface doesn't damage the computer.
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Follow Up By: Member - Frank P (NSW) - Friday, Jan 31, 2014 at 17:26

Friday, Jan 31, 2014 at 17:26
Ahh. Thank you Brian
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Reply By: Bob Y. - Qld - Friday, Jan 31, 2014 at 16:23

Friday, Jan 31, 2014 at 16:23
The part that Kerry mentioned above might be the headlight/indicator/wiper assembly. They burn out if high wattage globes are used without a super loom.

Reckon your problem might be the fusible link. Just off the positive terminal of the battery there will be a small "box" with 2 fusible links inside. From memory, the smaller one of the two will control the headlights. The other link controls the ignition or starting circuit, I think?

If you can't access the correct part, then a piece of household fuse would do in the interim.

Bob

Seen it all, Done it all.
Can't remember most of it.

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AnswerID: 525510

Follow Up By: Brian 01 - Friday, Jan 31, 2014 at 18:22

Friday, Jan 31, 2014 at 18:22
I would posit that the OP says he has power at the fuses, which indicates that the fusible link is intact.
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Reply By: Danny & June - Saturday, Feb 01, 2014 at 01:49

Saturday, Feb 01, 2014 at 01:49
HI Neill
Try fitting a new bulb.
Just might work.If one works try both bulbs.
Good luck.
Danny.
AnswerID: 525546

Reply By: Member - DOZER - Saturday, Feb 01, 2014 at 16:30

Saturday, Feb 01, 2014 at 16:30
In there somewhere is the door open, ignition off = turn off headlights relay...or maybe its the control for the headlight relay that has this on it.....it is all very complicated and my suggestion is to contact Pirahna, who do a headlight relay wiring harness.
b4 you bag me out, walk a mile in my shoes, then your a mile away and have my shoes :)

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