MBMB

I want to put brighter H3 bulbs in my '89 GT, and don't want to disturb the wiring as much as would be required to install an additional relay, so I'm trying to figure out from the wiring diagram how big the wire is back to the battery.

I'm looking at sheet 2 of the '89 wiring diagrams (marked "LIGHTS USA"). Page 97 in your hymnal, if you're singing along.

The wiring diagram shows a pair of fog lamps (L and R) and a pair of "additional high beams" (I'll call them driving L and R).

It shows a 1.5 mm^2 WT/YE wire running from fog R to O25, and a 1.0 mm^2 Wt/GN wire running from the fog L to O24. Then the two wires join up and run to terminal 87 of relay XIII. Terminal 30 of relay XIII goes to terminal 87 of relay IV (which is normally open, and is triggered by the fog light switch, among other things!) So if relay IV is closed and relay XIII is closed, the fog lamps are on.

Q1: Why different size wires for the two fog lamps?

Q2: How is this really wired, with no fog light switch?

The wiring diagram shows a 1.5 mm^2 WT/YE wire running from driving L to O22, and a 1.0 mm^2 BK/YE wire running from driving R to O23. The two wires join, go to connector 33, and from there go to the light combination switch (XXIII) and (via 2.5 mm^2 WT wire) to the dimmer switch (so that the driving lights flash when the dimmer is pulled back with the headlights off?).

Q3: Why different size wires for the two driving lamps?

Q4: are the driving lamps really not controlled by a separate relay? Are we really pushing almost 10 amps through that switch?

Q5: are the U.S. fog and driving lamps really on different circuits, even though we don't have a fog light switch? (By the way, behind my pod I found a taped-off socket for a switch like the six in the pod. Fog light switch?)

Q6: (for SWEANDERS?): on a US '89 GT, the pod switches, clockwise from bottom left, are: high intensity windshield washer; driving lights; headlights; rear window defrost; and hazard flashers. Are ROW cars set up the same? Where does the fog light switch install?

Thanks,
Mark.

MBMB

Answering some of my own questions, for those who might stumble upon these questions in a search in the future:

1. Still don't know. Will take the lights out and actually compare the wires sometime soon.
2. There is a fog light switch (the switch below the headlight switch). There is a foglight (controlled by the switch) and an auxiliary high beam (on when the high beams are on) on each side.
3. See 1
4. Yes, we are apparently pushing almost 10 amps through a switch in the dash. This seems like a dim idea to me ("trouble is, you see . . . sheep are dim"). I will certainly not try pushing 20 amps through the same switch.
Q4a: has anyone ever had their headlight switch melt?
5. Yes. Fog lights and aux. high beams are on different circuits. The taped-off switch may be for the secondary fog lights in Euro cars (rear fog light?).

Alan

Mark,
It been a long time - but I did in fact stumble on this in a search...!

Q1: Why different size wires for the two fog lamps?

Well each side you have a fog light and a driving light ("additional high beams"), the fog light is shown with a 1.0mm wire and the driving light with a 1.5mm wire. I don't know why they would be shown different given the bulbs are the same - 55W for both.

Note however that for all years main headlight wiring is only 1.0mm high & low beams - and is good for ~10A each.

Anyway the driving lamps always come on with the high beams directly switched by the column stalk. It is about 5A per side - so a little less than 10A through the switch...

The fog lamps come on supplied from the X-Bus repeater relay IV (on with acessory & ignition) and the fog light relay switched by a combination of the fog light switch being on (you should have one in middle left pod switch position???) and headlights off or low beams selected.

Q2: How is this really wired, with no fog light switch?

There should be a fog light switch as above... I think its there - you may be calling it a driving light switch...

The wiring diagram shows a 1.5 mm^2 WT/YE wire running from driving L to O22, and a 1.0 mm^2 BK/YE wire running from driving R to O23. The two wires join, go to connector 33, and from there go to the light combination switch (XXIII) and (via 2.5 mm^2 WT wire) to the dimmer switch (so that the driving lights flash when the dimmer is pulled back with the headlights off?).

Yes this is the "flash to pass" (pull stallk) - the driving lights have to flash if the headlight pods are down! so they always do (even with lighting off) - headlights flash only if they are on & up.

Q3: Why different size wires for the two driving lamps?

No good reason I can see - wire sizes are shown the same on my GTS - BUT it actually has 1.5mm wires for both...bigger than for the headlamps!

Q4: are the driving lamps really not controlled by a separate relay? Are we really pushing almost 10 amps through that switch?

Yes - in automotive terms 10A is not that bad - but if you wanted to upgrade the Driving lamps you'd do well to add a relay instead.

Q5: are the U.S. fog and driving lamps really on different circuits, even though we don't have a fog light switch? (By the way, behind my pod I found a taped-off socket for a switch like the six in the pod. Fog light switch?)

Yes I thnk you do already....what you call 'driving lights' below - are in fact the fog lights - the driving lights only come on with high beam mode. You can have them on alone by tuning on just the marker lights and selecting high beam. if the fogs are on selecting high beam switches you from fogs to driving lights (Euros do this differently).

BTW the taped off switch is to allow for the Rear Fog Light switch that only exists on ROW/Euro's - whiich goes where your intensive washer is...(and that gets relocated below the pod I believe).

Q6: (for SWEANDERS?): on a US '89 GT, the pod switches, clockwise from bottom left, are: high intensity windshield washer; driving lights (THIS SHOULD BE FOG LIGHTS) ; headlights; rear window defrost; and hazard flashers. Are ROW cars set up the same? Where does the fog light switch install?

Front fog light in middle left, rear fog lights in lower left - only the lower left is different for ROW/Euros.

If you want brighter bulbs - change your H5's headlight bulbs for brighter ones. You can go to 100W without any more than a fuse change....

Alan

MBMB

Boy, that was a blast from the past. Thanks, Alan.