123GT Consideration of Lighting Differences 
04/2013 R. Kwas, changes on-going


As a result of a Brickboard question on the wiring of the Volvo 123GT (Link:  http://www.brickboard.com/RWD/volvo/1562194/120-130/source_4pin_metalcan_relays.html  ), I looked into the wiring diagram in detail and discovered there are actually two versions...a USspec and a Eurospec, with subtle but significant differences in the wiring and function of the additional Fog and Spot lighting. 

(Refer to marked up drawings below)  In the US version, a single Spot Light and a single Fog Light is shown.  In the Euro version, two Fog Lights (only) are shown. 

In both versions, three additional relays are present in the upper right area.  In the US version, Relays 9 supplies the Foglight, Relay 11 supplies the Spotlight, and Relay 15 supplies the Horns.  It might be reasonable therefore to assume that function of these relays is similar in the Euroversion...but if there is no Spotlight in the Euroversion, just what does Relay 11 control??  In studying this wiring diagram, the answer is that Relay 11 is used to lockout the Foglights such that they are only available when Headlights are OFF.  It would seem that European regulations require this to be automatic and not under control of the driver. 

Summarizing, it would seem that there is only one Foglight and one Spotlight shown in the US version, and the Spotlight is slaved to the Hi-Beam headlights (that is, Foglight may be powered any time Ignition is ON, but Spotlights require Headlights to be on Hi-Beams before they are enabled).  In the Euroversion there are only Foglights shown, and these are locked out when headlights are on (that is, Foglights may only be powered when Headlights are OFF, but Markerlights are required to be ON also).  


123GT US version: 


123GT Euroversion:

Further info on Voltage on both sides of a load...Link:  AMP Indicator ON 


This article is Copyright © 2013.  The term Volvo is used for reference only.  I have no affiliation with this company other than to keep their vintage vehicles working for me and to help other enthusiasts do the same.  The information presented comes from my own experience and opinion, and can be used or not, or ridiculed and laughed at, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you donít, youíre just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and maybe wise-a** comment. 


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