headlights not working- fault finding procedure

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nrgserv

Well-Known Member
Posts
4,208
Location
shipley, west yorks.
slight break from my 109 thread (http://www.landyzone.co.uk/lz/f6/dug-out-109-a-189574.html) in order to look at the issue of the disco headlights packing up.

first off, assess what we have.
first position on stalk, ignition off, parking / position lights only.
ignition on, dim dip on first stalk position, second position should be headlights dipped / main but were loosing dip. main works ok when the stalk is flicked.
initial thoughts are either stalk problem or relay problem. using the rave operation and maintenance manual (available as a download on lz) we can look at the schematic and decide what / where to test.

page 1 shows the column stalk switch positions, using the key we can see we're interested in number 4, dipped beam.
following the drawing, this comes out of the column switch on connector 2 and carries on to an outbound arrow head and H1-2 (H= headlights, followed by page number within the section) and is depicted with an "A".
from the colour code we see its a "UB" colour. blue cable with a black tracer. (tracer is a narrow line along the lenth of cable)
Photo0328.jpg


turning to page 2, we see arrowhead with "A" and H1-1. as the arrow is pointing inbound, then the page number and "A" is where the cable is derived from.
the colour code is the same, and it terminates at connector "c2109" with relay "k236" plugged into it.
the idea of a relay is to switch a current that is controlled by either other relays or in this case a switch that has a lower operating current.
we see that with k236 operated the switch contacts should allow current between terminal 30 and 87, being supplied by fuse 4 in the engine compartment fuse box.
at this point i dont know if k236 is "pulling in", although i can hear numerous relay clicks when the headlight switch is twiddled.
we therefor need a test point.
Photo0327.jpg


following the outbound of k236 to "c H1-3" we can see it goes to the fascia fuse box. easy test point, reasonably accessible.
we're looking for fuse 10 &11, first for the obvious, to see if there blown.
visually ok, so for the tester.
Photo0326-1.jpg


most tester will do for this sort of stuff, you need one that measures direct current, the pic shows the symbol with the rotary switch pointing to it. i cant draw it......
if your gonna buy one, get one with ohms continuity on it too, it'll be useful. lesson later on that.
Photo0338.jpg


so, to test.
one end of the dc voltmeter needs an earth. easiest place for me was the fag lights shroud.
Photo0339.jpg


and the other probe gets used for the testing.
now, we're looking for 12v or as near as dammit, so until i see that i cant confirm ive got good connections on the tester.
a quick look at the drawings and the main beam are on fuse 4 & 5, and i know they work.
main beam on, and test each side of the fuse. (it was here i tripped meself up due to not thinkin.....)
Photo0340.jpg


Photo0341.jpg


with the meter connections confirmed, fuse 10 and 11 were tested.
nowt. twiddled headlight switch, still nowt. (still tripped up and not realised....)
so it appears i have a dicky switch.
this was removed for testing but as i'm writing this about 3 days later, i didnt picture it at the time.
easy to remove, 3 screws under steering wheel, pull trim off, 2 screws holding switch to column, gently pull switch out, disconnect connectors. (and mind the solid earth connector on the bottom, specially when reassembling!)
quick test with ohms on the meter, looking at the diagram i need to "get a buzz" from the meter between pins 2 and 6.
nowt. so check the meter, short the probes, yep gotta buzz.
checked pins 2 - 5, got the buzz. thats main beam ok.

click. doh. probably didnt need to take the switch out. doh again.

realised what i'd done before i tested the next bit, in that i'm testing for dip beam while the stalk is still on main beam.....

flicked the stalk, retested 2-6, got the buzz.
bummer.
reconnected switch, ignition on, tested fuse 10 and 11 on dc volts.
0.
bummer.

while the switch is out and i can access the terminals, i tested for volts on pin 2 to earth. 12volt. good.

so back to the diagram, i need to check i'm getting voltage to k236, pin 85.
now as i know theres a good chunk of lighting relays behind the passenger kick panel, thata where we're off to.
if you dont know where summats located, then in the back of rave theres a location index for every component, connector, splice, and ground connection.
using the colour codes for k236, i'm looking for a relay with a blue/black, black, brown/purple and blue/red wire going to it.

Photo0343.jpg


Photo0342-1.jpg


removing the relay from its bracket but leaving connected, holding it while twiddling the headlights switch i could feel it clicking. it has a signal voltage and earth, so do i have a supply on pin 30?
removed relay so i could stick a meter probe onto 30, and intuition took over after seeing the state of the relay.
covered in a layer of crud, been wet, dried out, contacts are gonna be knacked in that......
swapped it for another, instant headlights.

Photo0334.jpg


Photo0333.jpg


well after reading it back to meself, it all sounds horrendously confusing and some pics aint come out as clear as i'd like!
gonna leave it on anyway, on the off chance it helps someone else fault find.
in the meantime, i'll either hone the write up skills, or crawl back to the 109.....
 
Quick heads up .. if you want better (decent!) quality screen grabs, look for the PrntScrn button. This captures what's on-screen to clipboard so you can paste it into Paint/Irfanview/whatever, crop it, edit it and save as a jpg of decent quality to use. Saves getting the flicker/banding that a photo of the monitor gives you.
 
No worries .. If you want to send 'em via email to people, use Adobe online and turn 'em into pdf's .. small file sizes and will open on most computers.
 
thx very much indeed for the info, must have taken u while to do, i will have a go tommoz I was looking at the relays in the drop down tray under glove box. will let u know how i get on.
 
can you put a link in so I can download this please ?

rave operation and maintenance manual (available as a download on lz)
 
Thank you very much :clap2: for this nrgserv. I have been struggling with the same problem for days! Dare I mention Haynes? It does not list this relay. I will attempt to download the manual you use.

Kind regards

chapmanjj
 
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