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1991 745T. I just bought this car and have not figured everything out yet.
Installing E spec headlights. Found connectors at front lighting harnesses that have the right colors to match fog lamps. Black/white & black. Are these for fog lights? How do I get this switched? Have not dug into the dash yet.
Next, will the US high beam relay handle both the European high beam plus the driving lamps? Temped to just try & see. I'm an electrical guy so I understand these things and know they are usually over built.
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Bob
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Yes, the front fog lights in the later 740s are on violet/white wires (black is ground as usual) which go back to the front fog switch in the dash, all fed by auxiliary relay #127 (as Bill noted), which normally belongs in the front row of the relay tray, second socket from the right.
If they had been red wires they would have been connectors for the optional front headlamp wipers (which were standard on most 760s as I recall).
I can't recall if I've seen the other end of the violet/white wire in a switch connector tied up under the dash, but if it is present it will be in a small 4-pin connector tied to a black/white wire, along with a yellow, white/red and black wire. I suspect for the North American market, the violet/white wire may simply terminate at one of the large connector blocks up to the left under the dash -it's shown on pin 8 in the middle of the smaller half of a large connector block. You should be able to find it there and either tap into it or shove a Molex pin on the other side for a proper connection.
Looking in the FAQ here and as well doing a google search there are a number of articles and threads on E-code conversion, even a few Youtube videos. One good tip I saw suggested busting open the old 9004 headlamp bulbs and soldering the connector end to the E-code connector to make an adapter harness so you don't need to butcher the existing harness. As for the existing relay and wiring being up to the task, although Volvo didn't always over-engineer the spec for their relays, most mention I see is just to use the existing wiring.
After doing a little searching, I haven't come up with an on-line copy of the Volvo service manual wiring diagrams for a 1991 or similar vintage, which is why I went into a little extra detail above using my 1989 manual.
People who have actually done the conversion will hopefully post additional comments here.
I've always been tempted to do the E-code conversion as my headlighting sucks, especially on wet roadways with worn out line painting. The easier thing I really should do is put a better relay right up by the headlights to eliminate a lot of the voltage drop as described by noted lighting expert Daniel Stern (who way back when was an occasional brickboard contributor). If you want to learn everything there is to know about automotive lighting, look up stuff by Daniel; He's not only an expert, he's a real character.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Dave: One thing I will say now is that unless the main relay burns, I won't be messing around with that complicated voltage drop fix. These E spec lights solved all lighting problems. A tiny improvement over this is not worth the effort. The lights I have now are the best I have ever owned in any car. The previous best was a 90's Saab turbo with glass headlights. I don't intend to drive much at night anyway, but the original lights had a broken adjustment socket and would have needed replacing.
I found this: https://www.ebay.com/itm/142832617818
What do you think?
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Bob
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Yes, no need to get excited about voltage drop if you've got good E-code lighting. It would at best be a small improvement. Clear lenses and unfaded reflector surfaces would probably be even more effective for improving standard lighting.
Another thing to avoid is Long Life (LL) halogens, which many might choose what with our DRLs having the headlamps on full time. They actually consume about the same watts, but generally use a thicker filament to last longer that doesn't give off as many Lumens and produces a bit more yellow light. I know, I had them in for a number of years and didn't realize how poor they were until I had our two 940s side by side in the dark one day.
That Motor pro service wiring diagram manual for 1991 imports looks interesting and the price is certainly right. I see the last one on eBay just sold, so you? The diagrams very much look like they were cribbed out of the Volvo manuals, but I doubt they would want to break copyright. That introduces the possibility for errors, but even the green manuals have the odd error. It doesn't look like it includes component drawings and locations, which can be very helpful, especially for relay locations, connector blocks, ground points and harness routing. I also suspect it's just for North American market cars and USA in particular, and wouldn't cover the many international variants for some of the circuits as does the green manual. I'm sure it would serve your purposes well, but if you've got a choice, keep looking for a green manual, even a 1990 would be extremely useful.
As for the fogs, is there existing wiring to the auxiliary relay socket in the fuse tray? If you need an auxiliary relay then you can check out a genuine Volvo parts dealer website for the parts fiche to get the part number and cross reference that to something commonly available or one of the other relays that's the same to get from a yard. You can also use a rear fog switch instead of a front fog switch, the only difference is one is red and one is orange as I vaguely recall. I'm even wondering if you can piggyback the front fogs on the existing rear switch, but haven't bothered to think about that harder. With a bit of effort you should be able to find a number of yards who will have suitable 700/900 donors that do phone or online ordering, even international shipping.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Dave: I need to tell you that eBay seller is a crook. He sent about 30 pages ripped out of a 960 page manual and has not responded to messages. They were not even pages for a 740. He sells a lot on there and has a decent feedback rating, but when looking at the actual feedback, he does a lot of this and gets away with it due to volume. I am trying to get eBay to refund me. So I'm still looking.
I did some not pretty connecting from the headlight switch input over to the fog light switch to get it connected to the main ignition controlled relay. Then connected all output wires from the switch together and replaced the rear lamps with smaller wattage, still brighter than the bottom tail lamps. This got the fogs working any time I want them, without the headlights being on. Amps was just over 10 and I hope the switch will handle it. If I ever get a diagram I might try to use the relay, but this works.
It looks to me like the factory intended that the switch would need to be replaced to get the black & white wire connected if optional fogs were added. It was on a dead terminal.
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Bob
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Yep, I bought the manual. At that price it is worth the risk and it is very thick, so who knows what may be included.
As an old lighting engineer I know all about long life lamps. The commercial world has been full of that problem for years. Since retiring in 2000 everything has changed and I am no longer current. Yes, I "retired" at 50 and spent many years traveling as we decided where we wanted to settle. It turned out to be 50 miles from where we both were born. No' I wasn't really retired, but never held a regular job again.
BTW, I built an off grid home and every lamp in the place is LED. Lighting is no longer the biggest energy use. Now it is refrigeration.
I tried plugging a spare relay into the only space in the relay tray and got a buzz, so gave up on it for now. I suppose next I will have to figure out how to get that thing out. It looks like an impossibility. What I am hoping to do is use the fogs for daytime running and reduce the wattage in the rear, which will require some rewiring. Here DTR is not required, but still a good idea on two lane roads where nobody pays attention to the speed limit. Next I need to get into the FAQ's and figure out how to get the dash apart. The speedo needs repairing. The car came with two spares! I'm using a pretty slick app on the phone for now. Dare I tell you what it has recorded for top speed as I was passing a truck that was ignoring the speed limit? Montana is heaven.
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Bob
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‘ I suppose next I will have to figure out how to get that thing out. ‘
If you mean the relay tray, you remove the lighter/storage box above (pull the lighter bezel forward to expose two screws, swing the tray out from the left to free the grip tabs on the right, be extra, extra careful with the lower angled screw not to dislodge the far retaining clip, use your finger underneath), disconnect the lighter then release the two side clips on the relay tray. Lift up and pull forward. If the boa constrictor cable on the back isn’t too caught up you can pull it forward enough to flip over, or at least use a mirror underneath.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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hi bob,
get the excellent volvo service manual wiring diagram for your model year to
address wiring issues. it has everything you need including component
locations.
there's an additional relay for the e-style fogs called the auxiliary light relay. item #127 in the 1989 740 book. there's a spot for it in the main fuse/relay block.
i added an extra relay for ecode light conversion in a 93 940 that is similar to the canadian volvo circuit where they have drl. there's different circuits for different countries.
here's an 1988 740 book at ebay- you can look at the photos and see how detailed it is.
https://www.ebay.com/itm/164026450100?hash=item2630bd00b4:g:HYIAAOSwOhxeGOeb
search for the 1991 book. the wiring diagram files were all over the internet before, but now have mostly disappeared, replaced by what look like google proxy sites that claim to have everything, for a fee of course. the search engines don't readily cough up the free files anymore.
here's the engine circuits, only part of the 89 manual:
sorry the lights circuits aren't here.
http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm
maybe someone can point to a good link to the 91 manual?
good luck, bill
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Since I don't have any experience with the 700-series and you're an electrical guy, I'm going to let the diagram below do the talking.
The whole document is buried deep in the Volvo Oz archives which can be found here. Search for "wiring" and look for a document named "TP31075-1_760_wiring_diagrams.pdf".
As I'm in Europe, I don't know the differences between the European and US versions. In order for you to make your own judgements I can tell you the specs of our headlights:
The European units are designed for H4 bulbs. These bulbs are dual filament bulbs with a 55 W dipped beam and a 60 W main beam filament. There's one H4 bulb per headlight unit. Nothing new here, I guess, but I thought I'd mention it just in case.
I'm reasonably sure that only one filament is active at a given time, either dipped or high beam, to avoid thermally overloading the bulb envelope.
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That's a 760 wiring diagram. Wire colors, relays and fuses are different from 740s. Bill has given him the correct info. He just needs a link to an appropriate Volvo service manual wiring diagram that has the relevant front fog light pages. In the 1989 740 manual, for a USA car (i.e. North American market) it's on pages 94-95. For a 1991 manual it will be on similar pages and very likely identical wiring as the lighting wiring harnesses didn't change much through the years.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Yes, when it comes to engine related parts of the diagram, I can imagine that there will be differences, but not when it comes to stuff that is shared between the models, like lighting.
In this case the white/black wires in the diagram ("W-SB") to the front fog lights correspond to the colours mentioned by BrickBob. If it hadn't, I'd have left it well alone.
The diagram also shows the fog light switch and relay and the violet/white wire between them.
Most of the links to Volvo manuals have disappeared from the net. You now have to make do with what you can find and see if it is applicable to your model year. More often than not, it is, even though, strictly speaking, it isn't. Volvo didn't set out to change wiring looms every year. But yeah, caution is advised.
I often revert to looking at the '86 diagrams for my '92 245, because they are far more legible in the Haynes manual, and I find the shared stuff is identical, right down to colours, etc. And I see you're using an '89 diagram to answer questions for a '91.
Again, I'm not saying this is always the case.
BTW, this document (TP31075/1) is from Volvo North America Corporation.
This manual not only deals with the B280F equipped car, but also the B230FT, differences between the two are clearly listed.
Bill linked to wiring harnesses that did not show light circuits, so did not provide any answer.
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Black/white wires were also used for the front fogs in the 940 series. 740 harnesses are probably more similar to 940 wiring harnesses than 760/960 wiring harnesses. At some point after 1989 the 740s obviously changed from the violet/white fog light wire before the end of 740 production, which I find a bit odd as nothing much else changed in the final couple of years. The locations of relays and fuses with the 760/780/960s were quite different from the 740/940s so wiring harnesses were also often quite different, although there was likely some degree of consistency in the colors when the same engineers and harness suppliers were involved. A 760 manual is certainly better than no manual at all, especially when looking at common components and things like engine wiring for the B230FT used in both series.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Thanks for all of the replies. It will take me some time to sort this out and I will report back. My 740 definitely has black/white wires in the headlight harness. I'll need to do some testing to see if they are what I think and will try to buy the manual because I need to be prepared for electrical issues. The Haynes manual is practically worthless. Oh, the sockets for the signals and parking lights were fun. I had to modify some found locally.
I hooked up the new lights to existing wires and relays and everything worked except the fogs. We'll see if the relay holds up.
The lights are fabulous and didn't even require aiming. They were used and had a couple of issues; one being a broken bolt that was impossible to get out. There will be no finding a piece of trim around here, so I will be modifying the old one. It's a driver, not a show car. We drove it to town (over 100 miles round trip) on Wed. Here in Montana we never see other Volvo's. As far as I know, there is one other 740 in the county and no other 240's It sits 90% of the time and we drive the old 240 locally. We now own 4 vehicles. The 740 has the least miles at 154K. All the rest are over 200K.
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Bob
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