Testing my Indicator/Horn/High Beam/Low Beam Cluster Switch

[Troll Hunter]

Vehicle:  LHS 1991 110CSW originally with a V8 and LT77 but now with a 300Tdi and R380

I'm gradually re-assembling the electrics on this vehicle, and in an attempt not to do work that has to be redone I'm trying to test all switches etc before re-installing and connecting them.  I'm currently testing the above cluster, which appeared to be working correctly before the strip down, but now appears to be very suspect.

Looking at the connection plug, centre of the last pic above, numbering the pins L-R top row 1-4, and L-R bottom row 5-8 the cables connected are:

1.  Thick Blue/White

2.  Thick Blue/Red

3.  Purple

4.  Purple/Black

5.  Thick Blue

6.  Green/White

7.  Green/Brown

8.  Green/Red.

Testing for continuity between the various connector pins with my multi-tester, the only pins which seem to complete a circuit are pins 1 and 5, with the High/Low beam switch in the High Beam position.  Regardless of all other pin combinations and switch positions no other connections are made.  I was expecting an Ignition ON feed to supply the two indicators, and the Horn and both headlamp circuits to be fed from an Always ON supply.  I'm obviously wrong, or the switch is duff, but it seems unlikely that headlamp connectors, indicator connectors and the horn connector are all faulty.

Please comment, correct me, and tell me what I should be expecting with this switch cluster.  All input will be very welcome, and many thanks in advance for any help I get.

Mike

[FridgeFreezer]

How are you testing?

Multimeters put out a pretty weak signal on the ohms range which may struggle with dirty contacts - if you have a continuity buzzer option, use that, or use a test lamp or similar, something that put a little bit more load through the switch.

[Troll Hunter]

OK, FF, I was using my multi-tester.  I'll try a test lamp and report back.

Mike

[Troll Hunter]

An update.  I used a 12 volt battery and a test lamp.  A slight improvement with the test lamp in so far as there is contact between pins 3 and 4, so that means that the Horn is live.  Unfortunately, no other changes.

Mike

[steve b]

The clamp is broken on that switch Mike .

Steve

[Troll Hunter]

Good point, steve b, thank you for pointing that out.  I would obviously have found it when I came to mount it, but it's scary how blind we can be to one aspect when concentrating totally on another aspect.  That probably means a replacement switch☹️.  That might be a good thing, though, as it should solve my other apparent problems.

Mike

[steve b]

That clamp is super weak and easy to snap . If you can resolve the circuit issues it's worth looking at some sort of get around as the factory switches are much better than replacement pattern or OEM . I've done it by chucking the broken tab and forming a steel strip with tab and an overlaying radiused strap to wrap over the remaining plastic curved section 

Steve

[Troll Hunter]

A good idea.  Thank you for the suggestion.  I'll have a look at my options when I get back into LR work, hopefully tomorrow.  Today I've had to replace a front brake hose on our daily driver.

Mike

[Troll Hunter]

Not been on here for a couple of days.  The failed brake hose, above, was followed by replacing rear brake shoes and fitting new links to each end of the front sway bar.  Rubber bushes gone but still had to be removed by Mr. Grinder and Mr. Lump Hammer!

OK, back on LR stuff.  So, I've identified that the horn contacts work, and the headlight dip appears to make a contact between pins 2 and 5.  The rest seems to be totally dead.  Can this switch be taken apart and the various contacts cleaned?  Shipping and duties will more than double the price of a new switch, so I repair whatever I can.

Anybody else got any views or comments on the apparent lack of connectivity, please?

[simonb]

The switch will come apart, you may have to drill out the rivets, however it will ping out a load of springs and small plastic parts, so beware. You then need to get them all back in place before you bolt it back together. You may find the copper contact pads are burnt out when you get it apart, so a new switch maybe the only option.

[Troll Hunter]

Thanks, simonb.  I'll have a catch net handy, and report what I find.

Mike

[FridgeFreezer]

19 hours ago, Troll Hunter said:

The rest seems to be totally dead.

Are you sure it's dead or could it be you're just not probing the right wires in the right order?

[Troll Hunter]

Yes, I was sure it was dead.  I had tested every combination of pins in every switch position.

This afternoon I stripped the switch, very carefully so as not to lose any springs, etc.  The little white plastic bits that fit in the tops of the springs were very well worn, and two were missing, presumably worn away totally.  the switch contacts were  in poor condition, burnt.  Not really surprising that I wasn't getting the contacts that I expected.  So now it's time to order a new switch.  Any recommendations for or against any particular manufacturer or supplier (Blue box is automatically barred)?

Having found significant wear on the horn/dip/ indicator switch I decided to check the wiper/washer switch.  This was in much better condition and only needed a good clean and the ball bearing re-greased.  That was good news, but not unexpected since the wipers and washer are used far less than the dip and indicator functions, specially as the vehicle spent the first 9 years of its life in Kuwait.

Mike

Many thanks to all of you who have given views and made suggestions.

[steve b]

Lucas have launched a range called classic 4x4 genuine parts - 90/110 early type connector STC439LUCAS. 

There is a website www.lucasclassic4x4.com 

I picked up a catalogue from Britcar a few months ago but they are now closed . 

If it was the headlight contacts burnt out I  would suggest a relay kit for the dip and main circuit loads 

Steve

[Bowie69]

I would love to see some side-by-side comparisons of blue box, allmakes, 'G' marked parts, lucas and one from LR direct, see what the differences are on a, say, headlight switch.

[Troll Hunter]

I'm afraid, Bowie69, that side-by-side comparisons are just a dream.  There are far too many variables.

Many thanks, steve b, for the link to the Lucas site.  Dare I hope that their products are made to the original specs?  Anyway, I'm going to throw my money their way, and see what I get. I've noticed that there is a significant variation in retail price for their products.  Looking at only a couple of sites I've already seen a 25% reduction from the more expensive site!  Worth searching!

Mike

[FridgeFreezer]

I second Steve's suggestion - relays on the lights will give it a much longer lifespan.

[Troll Hunter]

Almost on the same topic, but a bit broader, so, Admins, please shift it if necessary.

I'm referencing the LR manual for 300Tdi wiring diagrams. However, it appears to be tilted towards the later models that have ECU. Since my vehicle doesn't have an ECU what allowance should I make when reading the diagrams, or is there an equivalent document for the earlier 300 models, please?

Mike

[western]

300tdi only has ecu for alarm system& egr if fitted, you can just ignore those bits. 

[Peaklander]

I use the 97MY diagrams for my 96 300TDi 110. The PDF file format means that they are fully searchable and so very useful. As Western says, just ignore the bits that you know you don't have. So far in doing so, I have found that everything else is the same as on my vehicle and I have been through all the electrics.

Edit: I do have a scan copy of the much earlier 300TDi drawings but they are virtually no use. I think the only part that I used was to look at the turn indicator warning lamp circuit (common bulb to both sides), when I was moving to LED.

Edited December 10, 2021 by Peaklander