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-   -   Amazon: Light switch problem. (https://www.volvoforums.org.uk/showthread.php?t=100943)

Alf ista Jul 25th, 2010 01:21

Light switch problem.
 
Hello everyone. I have a recurring problem with my light switch. It works the lights fine but has a problem with lighting the gauges inside the car. I have replaced it a couple of times and the latest one is playing silly beggars now as well. No amount of twisting it is working this time. I remember someone saying on here before that you could cross two of the connections so that the gauges light up fully when the lights are on, there by bypassing the adjusting function. This is what I want to do. Can someone tell me which connections to connect? And any ideas about the best way to do it? Below is a pic of my original switch which should help with the description. Many thanks. Hugh.

http://i191.photobucket.com/albums/z...ightswitch.jpg

Derek UK Jul 25th, 2010 12:42

I think you'll find that it's the pair at 11 and 1 o'clock, the outer ones of those 3. Even if that switch is duff it'll probably show something on a meter if you check it. Turned to one extreme it should be open circuit, that is the dash lights off position. A couple of inches of wire with a piggy back crimp on each end that duplicates the spade will do the trick.

Ron Kwas Jul 25th, 2010 13:35

Alf Ista;

I have to disagree with Derek on this one......he is suggesting tying together 30 and 58...I don't believe that will bring the desired result...30 is power coming into the switch and 58 is the parking light output...

I'm referring to wiring diagram here: http://www.sw-em.com/122S%20Wiring%20Diagram.jpg

Terminal list for Light Switch with function and color codes:

30 - Power input (2 Blacks)
58 - Parking Light output (White)
56 - Headlight output (Yellow)
58b - (Full) Instrument Lighting Input from Fuse 3 and output to one nonvariable (2 Whites)
58a - Variable Instrument Lighting output (3 Reds)

...unfortunately, the variable output terminal which powers the Instrument Lighting is not numbered in that drawing...but by the process of elimination, (and you should be able to confirm this by checking colors of wiring connected to your Light Switch), I believe the terminal of interest to be 58a (at 7o'clock)......so by my reckoning, taking the 3 Reds from terminal 58a and tying them to 58b, will bring the desired result of bypassing the variable function. The make special "piggy-back" terminals which plug onto a single male contact and which have two males themselves which I would recommend using for this.

http://t2.gstatic.com/images?q=tbn:vK6OD1HBiNvquM:l

Note: After this modification Fuse 3 will continue to protect all non-variable Instrument Lighting, and an increase in fuse current rating (from 8A) is not required by this change.

Cheers from Connecticut!

Alf ista Jul 25th, 2010 14:20

Thanks Derek and Ron. Indeed, I checked the switch that is on the car at the moment and all the colours and wires match Rons list, except for 58a; I have only 2 reds on here, not 3. Looks original wiring and all works fine, maybe different this side of the pond?
Currently, I have some extra gauges fitted and the power to lights from these is piggybacked off 58a like Ron says. So, if I move all wires from 58a to 58b that should do the trick. I have those piggyback terminals as well. Will try it today and let ye know how it goes.
Hugh.

Derek UK Jul 25th, 2010 17:17

I wrote out a reply which said that I thought that the 2 lower tags at 7 and 5o'clock were the likely ones and then remembered that I had a spare switch here at home. With a meter, the only 2 contacts that I could get any readings at all on were the ones I posted. These readings weren't very consistant but I've never had it on a car so don't know the condition of the rheostat. Yes, I have been told not to assume things when doing this sort of check but I did so this time. If you drop the switch out of the dash, assuming(!) there is enough slack, it should be easy to bridge the terminals to check. A dark garage will help!
Good info Ron. I've got a mail to write to you about red light problems on an ES. I'd appreciate some insight if you've a few minutes.

Ron Kwas Jul 25th, 2010 17:34

Hugh;

That slight inconsistency with number of Reds may indeed be due to sight variations which occur, but as a rule, you can trust the oe color codes...you may even be able to verify colors on terminals in-situ without removal from dash...this will take a flashlight (torch) and some contortions, but is certainly doable also...

Derek; I value your inputs on this and Brickboard Forums...and everyone can make an honest mistake...the trick is not to devolve into a personal attack, and I am very careful not to when disagreeing with someone...I've found both Fora civil and pleasantly proper that way...thankfully(!), in comparison to others out there...of course were all adults here which is not what can be said of other places out on the web...as far as your electrical issue: Fire away (...did I say Fire?)...I'll try to help...and like I always say: If I don't have an answer, I'll usually have an opinion!

Cheers from Connecticut!

Alf ista Jul 25th, 2010 21:55

Well, problem solved. And it wasnt what I thought initially. When I didnt have dash lights I assumed an old problem had raised its ugly head again. Not so though. When Ron mentioned fuse number 3, I had a look and sure enough it was blown. So why did that happen then? Time to find out....
I have just fitted an extra gauge, a voltmeter in fact, I reckoned this was the cause of the problem. Sure enough a further 3 blown fuses narrowed it down. The light bulb that came with the gauge had 2 wires instead of the usual 1. I fugured the 2nd one must be a separate earth. So thats what I did.... and thats what caused the fuse to blow. I replaced it with a spare single wire bulb and no problem.
So, what I thought was a problem wasnt, but it did point me towards where there was a different problem, so there lies the silver lining!

Mind you this thread may help other people who have a problem with their dash lights.
Thanks again to Derek and Ron for the help. Much appreciated!!
Hugh.:notworthy:

Ron Kwas Jul 25th, 2010 23:27

Hugh;

...glad to help and happy to hear you got it squared away....

...don't forget troubleshooting rule No.1: Always question and consider the most recent thing was touched when troubleshooting a new problem.

Cheers

Alf ista Jul 26th, 2010 01:00

Indeed Ron, Whats that they say about if you assume.... you make an a** out of u and me....lol
Anyway, I fixed it up, and took the old girl out for a nice spin around the country roads this evening, no better car for it!

Ron Kwas Jul 31st, 2010 18:58

Addendum...
 
1 Attachment(s)
Guys;

I realize this issue is already solved, but I had made a marked-up drawing of a 122 lightswitch to show the dimmer bypass, back when the thread was live, which I had trouble posting at the time. I am adding it now for the sake of having everything in one place.

Since it comes up occasionally, I will likely also write this up and add it to the SwEm Tech articles.

Cheers from Connecticut!


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