Electrical: Lighting, Horns                                                                            FAQ Home
Volvo Maintenance FAQ for 7xx/9xx/90 Cars                                                                                                                     Version 5.0

Bulb Failure Warning Sensor.  [Editor's Note:]  See http://www.mikeponte.com/volvo/bulbsen.htmfor Michael Ponte's discussion of how the bulb failure warning sensor operates.  This sensor is located in the relay panel shown at Relay Locations.

Lighting Circuit Preventive Maintenance. Outside of routine maintenance, there's one thing that needs to be done periodically (but may be different on your '90 7xx series due to new headlight system as compared to the four headlamp '89 models: remove the headlight grounding spades (behind the headlamps on the inside fender) from the grounding strips and clean the contact points. These crud up (oxidize) and create some weird and funky problems with the headlights.

Headlamps Burn Out Frequently.  [Query:] The halogen headlamps burn out on my ' 93 Volvo every 3 or 4 months.  Does anyone else have this problem?  The dealer assured me that there is not a short in my car.  As a matter of fact, the dealership went as far as to blame it on moisture. [Response 1:] When you install the light bulb if it is touched at all by your hands or anything oily or if it is scratched it has a very high potential of burning out or even exploding. Also, water vapor inside the headlamp due to a hole or badly sealed headlight will cause bulb failure.  You might want to check all seals in the headlight area.  The bulbs will go out rather fast once the seal has been breached or there is a crack in the glass.  [Response 2:] I have had the same problems with two Volvos we bought and found that the voltage regulator had an intermittent fault. One day I noticed that suddenly the lights were very bright for a few seconds and then back to normal, bulbs don't like that. I replaced the voltage regulator on the alternator. This solved the problem. These screw-on voltage regulators are not expensive (US$25) and are available from your Bosch agent.

Headlight Circuits/Relay Won't Function. [Symptom 1:]My lights are out. The car is a 760 turbo '86.The parking lights work fine but not the beams, although I can flash the hi-beams. I've checked the fuses already as well as the wires. [Diagnosis:] Funky headlight behavior is a KNOWN bug in 700 series cars. First thing to try is removing and cleaning the headlight connections at the headlights and, more importantly, removing the wires (spade lugs) at the grounding strips located on the interior fender well behind each bank of headlights and giving them a good cleaning (sanding is suggested). If that doesn't clear it up, it's likely you have a bad headlight relay which is typically located on the relay panel behind the lighter/ashtray assembly. Consult a manual or the chart on the back of the ashtray for the proper relay. I'll lay odds that the ground points are the problem. [Symptom 2:] My 85 740 has a problem with the headlights blinking. I've traced this down to the relay, which is getting so hot that the plastic insert in the fuse panel is melted. One of its terminals must have been heating up substantially, to the point of major discoloration of the relay terminal, and rusty-looking gook in the socket, only for the one terminal blade. [Fix:] Replace relay at relay panel. However, I found a Volvo TSB on headlight and fuel pump relays that described this problem, and indicated that the fix was replacement of the relay, its' socket, AND the wire terminals which connect to the socket.

[Procedure 1:] To do this the correct way, you'd want the car to have a full tank of gas, weight in the driver's seat equivalent to the most frequent driver, and the car on level ground 25 feet away from a vertical wall. You then would mark the wall:

(c) is the aim-respective center of the headlamp (usually indicated by "H4" or another mark on the headlamp lens...if no mark, take a careful guess by looking at the bulb location.)
(v) is the centerline of the vehicle
b-b is a line parallel to and three inches below (c)-(c)

[Fix 1:] I use a product called "Worksite", which I obtained from Gall's, a police supply catalogue. It cleans and polishes plastic, and is sold by this outfit for use on police lightbars. I used it on my Saab's plastic lenses, and saw pretty good results. It was pretty inexpensive, around $5 or so.

Fix 2:] I used "Mother's" chrome cleaner. I tried it on a small bit of the corner of the lens. Wonder of wonders, miracle of miracles. The lens is very much improved. Still a tad yellow, but not bad at all. I expect that any kind of mild abrasive would have the same effect, even toothpaste.

[Fix 3:] Next time you replace them, use a sheet of iHg from 3M. It's a 1/8" thick, flexible, ultra-clear, UV-stabilized polyurethane sheet with 3M ultraclear adhesive on the back. You clean the lens with rubbing alcohol and press the stuff in place, and it disappears. Its flexible surface shrugs-off the rocks and stuff, and if it ever gets damaged, you can peel it off and replace it. It's available for many makes and models of cars (and even has the three little cutouts for the three little pips on the lens if you buy the precut kind) or in bulk sheets. Anyone running a post-85 US spec Volvo should consider covering up those headlight assemblies. Very spendy, and you don't want them absorbing the road-grit/rock impact. There is a company in Bellevue WA that specializes in clear protective automotive films (Stongard, 800-350-4897 www.stongard.com) They sell a 3M film that's supposed to be fairly easy to apply. Their stuff is very popular with the local Porsche Club(since the way the front end of a 911 is shaped, it collects a *lot* of rock hits, and those round H1/H4 headlights are an amazingly spendy integrated unit), and the 9004 headlight is a pretty common shape, so they've probably got pre-cut sheets for them already. 1990 740: Headlamp kit 76-04-70 $59.95.

1. CLEANING FRENZY. Clean the reflectors and lenses with a can of compressed gas such as that for cleaning computer keyboards or circuits. That should get rid of accumulated dust. In cases of heavy dust/dirt, you can clean manually with alcohol and soft rags or big Q-tips, but be very careful not to scratch the reflectors or remove the reflective coating. If that coating is poor, buy new light clusters or disassemble completely and repaint the reflectors with silver paint. If there is heavy dirt in there, find out why and fix it. The gaskets sealing the exterior may be "perished" (as the Brits would say). You can replace crumbling gaskets with silicone seal - apply a thin bead to the seating groove, then lightly oil the lens side and mate them while the silicone is still soft but has skinned over slightly. If you can't get the taillight clusters apart to clean them, one trick is to put raw rice and soapy water in there, shake it around, drain, rinse repeatedly with distilled water, then air dry for 24 hrs.

2. CHECK CONNECTIONS. Check the condition of the various electrical connections to the bulbs back there. Often there is room for improvement, especially in Volvos. Benz connections are usually OK in my experience. In some cases, a better connection at the bulb base is as easy as bending the spring connections deeper toward the bulb, so that it exerts more pre-load against the bulb when it's installed. Many Volvos have fragile connections molded into the reflector assembly and there is no practical way to repair them. Benz connections are often ferrous, so accumulated moisture in the trunk causes rusting which in turn causes resistance in various places. Renew or clean thoroughly.

3. WIRE UP UNUSED BULB SOCKETS. Many of our cars have unused rear fog lamp sockets in the tail light cluster. One trick to get brighter brake lights is to use those reflectors as additional brake lights. You may have to install a socket first, because there usually is none. This is especially easy in Volvos due to the twist-in bulb sockets - find one at a junkyard. Then connect the new socket in parallel with the existing brake lights. Make sure that your brake light fuse and wiring is sufficient to handle the extra load. I've been doing this for years and never had a wiring problem or blown fuse.

4. IF YOU HAVE ONLY DUAL-FILAMENT BULBS, STOP HERE. I'm not aware of any way to replace dual-filament tail/brake bulbs (1034 or 1157) with brighter ones. If you have any tips, please let me know.

5. BRIGHTER TAIL LIGHT BULBS. Replace the stock single-filament tail light bulbs with #105 bulbs. 105 is the number that Sylvania/Osram uses, and I suspect that it's a standard in the US. Don't worry that it says they are for trunk/courtesy/map lights - they don't run too hot such that they would damage your reflectors or lenses. I've been doing this for years. This takes you from 4-6 watts up to 10 watts of light, making them noticeably brighter. There are also 20-watt bulbs available in about the same size that will fit, but I don't recommend that because of heat and the fact that your taillights will be about 50% as bright as your brake lights. However they might be useful for your front market lights if you want a pseudo-DRS look (why anybody would want DRS is a mystery to me).

6. BRIGHTER BRAKE LIGHT BULBS. Replace the stock single-filament brake light bulbs with #3497 bulbs. These are relatively new from Sylvania/Osram, and their high price makes me suspect that they are halogen. They're about 30% smaller than the stock bulb, but rated at 28 watts instead of 21 watts. The smaller size should keep any additional heat away from the plastic lenses. Just the same, I would monitor the lenses closely for a few months, because this is a new setup for me and I'm generally cautious when trying out hotter bulbs.

[Note:] Don't buy USED 700 series corner markers....the faulty part of these units is the adhesive (holding the lens to the housing) and if it's been around, it WILL fall off. If you do get a used unit with the lens intact, epoxy it for a safety measure. So far it's worked for me on the one *new* unit I have on my car. [Problem 2: any solution to the falling out backup light problem; i.e., a source for the white plastic lens?] [Fix:] Just go down to your local Volvo dealer and buy a new clear backup light lens for about $4 to $6 and glue it in with silicone sealant. Volvo knows they had a product problem with these lenses and came up with a fix much cheaper than replacing the entire tail light assembly. Just be sure to specify right or left, as they are different.  See also Re-Glueing the Lens Components

Here is how I went about it:

1. Using a soldering iron with a flat (ie cutting) tip, I cut out the part that I needed from the donor lens making sure to cut it about 1/8" oversize. I couldn't find a way to unglue the lens from the black plastic back of the lens, so I cut that also using the same method.

2. Using the soldering iron, a utility knife and a Dremel tool, I removed the black plastic back and the glue so as to remain with only (part of) the lens itself.

3. Using the same method, I removed the glue and broken pieces from the recipient taillight.

4. With files and the Dremel tool, I adjusted the donor and recipient parts until they fitted together perfectly. Obviously there is no need to do this if you have a whole good lens.

5. Once everything fitted, I glued together the 2 parts of the lens with plastic glue (more flexible than epoxy) and glued the transplanted lens to the black plastic back using silicon sealer. I used black but would recommend transparent since you do see
some of it through the lens.

6. I used a permanent red market to cover up anything that didn't look quite right and with a fine brush filled the seams with... my wife's transparent nail polish.

That's all there is to it. Unless you're specifically looking for where the two pieces of lens are glued together, it now looks just like any other taillight in good condition.  The whole matter took me about 2 hours, half of it figuring out how to go about it. It shouldn't take much more than half an hour if you transplant a complete good lens.

Re-Glueing the Lens Components. [Query] You know those clear back-up lenses (cemented onto the the rear lights housing) on 900 and 800 models that tend to pop off at the car wash? What is the best cement for sticking them back on? [Response: Tom Irwin]  Remove all the old adhesive, clean the surfaces with denatured alcohol, PRIME both surfaces with a cyanoacrylate primer such as loctite #770.  Then a thin viscosity cyanoacrylate (super glue) adhesive on ONE surface.  Press into place for 30 secs.  [Response: Jim Bowers]  I used clear RTV adhesive sealant to put the one back on my old 745. It held for more than 5 years.

Water in Taillamp Lenses. [Symptom:] My tail lights (85 740T) are half-full of rainwater from el nino. After much frustration from changing gaskets repeatedly with no results and making repeated trips to the dealer to buy the replacement bulbs, I am contemplating drilling small drain holes in their bottoms. Is this advisable? [Fix:] I had this problem more than a year and half ago. I drilled such holes, and never had a problem since. I live in England where the weather is wet more often than dry, all year round.

Euro Side Lamps Wiring. [Questions:] Are US-spec 700/900 series cars pre-wired for Euro side marker lights (the fender-mounted repeaters)? What are the options to install these on a 1994 945t? There's no visual check for pre-wiring as on the 850 series, and I don't detect ready access to the fender area behind the badge. [Response:] As far as I know, none of the US spec late models are pre-wired for the fender mounted repeaters. You can run the wires into the interior and hook them up, though I find that the easier solution is to use a coathanger wire to pull them through the fender forward to the front turn signals and connect ground to the connection point on the inner fender (several blank tab terminals available) and connect the hot side to the turn signal lead with a scotch connector. On the inside fender near the front, there are a number of round plastic plugs which provide access for rustproofing, etc. You can remove one of these, insert a wire rearwards until it is visible at the hole for the signal. I have easily fed a fish wire from the front toward the rear - much easier than going from the light location forward. Just put a slight curve in the wire so that it rides over the inner fender liner and ends up near the opening for the light. Fasten the signal wires to the fish wire and pull them forward. I then cut a small 'X' in the plastic plug and pull the wires through it. Reinstall the plug and attach the wires. Note that the stock Volvo pigtail wires that fit the plug for the turn indicator are not quite long enough to reach all the way to the front turn signals, so you will need to solder some extensions on to them. I usually try to use extension wires that are correctly color coded for the front turn signals. It is also helpful to use some 'quick loom' to cover and protect the wires that are inside the fender. Where the repeater lights go into the fender, there is a rubber plug in the inner panel behind the outer fender. You will need to remove this plug as the connector on the back of the repeater will extend into this hole. Also, be sure to leave enough slack in the wires to allow you to easily remove the repeater from the fender with about 6" of wire. The IPD extension wires are just the Volvo pigtails with some extensions soldered on and the whole thing closed inside some flex or quick loom covering and electrical tape at the ends along with a couple of scotch connectors.

Basic Upgrade Information.  [Query:] What kinds of after market fog/driving lamps are you guys using? I need suggestions on a good pair for my1990 740. I’m not too afraid of drilling and all that other stuff, so what would be the place to mount them?  [Response: Daniel Stern] This question has no real "correct" answer, but it has a whole bunch of INcorrect ones, so let's get those out of the way first.
    Don't waste your money on the trendy little "eyeball" or "flat oval" shaped junk from e.g. Blazer, Tenzo, Catz, or any of many copycat companies. They're toys, meant primarily for kids who want to think their car looks "kewl". (Nobody has ever given me a definition for "kewl"...I'm still waiting...)
Now, to answer your question with a question: What is your goal? You're dealing with *ROTTEN* original-equipment headlamps, so neither your low beams nor your high beams are much of any good. My first and loudest suggestion would be for you NOT to buy any auxiliary lamps at all--from me OR anyone else--and instead to save your money up for a European-code ("E-code") headlamp changeover. This will not be inexpensive, but will make tremendous improvements *EVERY* time you drive your car at night.   Adding auxiliary headlamps to rotten main headlamps is a band-aid; replacing the lousy main headlamps with real working ones puts auxiliary lamps back in the category they belong in: Additional supplements to handle special situations, not necessary stopgaps. The E-code headlamp changeover can be had at favorable prices from Verrigni.
    Suppose, though, that you are fully aware of your current headlamps' low performance, but you also have determined that you will not spend the money--now OR later--for the E-code headlamp changeover. In that case, your task becomes one of making the best of a bad situation and choosing your auxiliary lamps wisely. You need to be discriminating not only on the basis of lamp performance, but also on build quality (skip the low-end "consumer grade" plastic stuff...find units made out of glass and metal) and on long-term serviceability (find lamps that have replaceable lens-reflector units so you're not stuck shelling out the cash for a complete new lamp assembly when a rock takes out a lens or when 10 years' hard use deteriorates the reflectors.) There is, as I say, no need to uglify your car with the odd-shaped black plastic stuff on the market; there's also no call to plaster great big chrome lamps on the front of your car (unless that's the look you're after). Sufficient stylistic variation exists in the realm of *good* lamps that you can find something that will integrate well with the front end of your car AND work well.
    I imagine you'd want rectangular lamps on that car (though I may be wrong; maybe you prefer rounds). If in fact rectangulars are what you have in mind, I recommend two pairs of Cibie 35s. One pair of yellow fogs, to be mounted below the bumper as far apart from each other as practicable. One pair of clear drive beams, to be mounted above the bumper just inboard of each headlamp. The fogs would fill-in the black hole" left on the road foreground by the low beam headlamps and add width to the coverage. The driving beams would add punch to the high beams.
    Other alternatives exist...Marchal 950s, Cibie 95s or 175s, Hella 220s...make sure you know what you're getting, though, because some of the widest-available manufacturers (I'm thinking of Hella here) make a random mix of junk and good stuff.

New High Performance Headlamp Bulbs. There is test of PIAA, Philips, Osram bulbs. Use archiv search and the AltaVista translation engine. It is in German and pretty explanatory. http://www.autobild.de/archiv/ausgaben/1999/
It is first issue in October  "Heft 39" under "Produkttest und Gluhlampen" title.

Brief translation of article from Marc:

Tag line: In headlights there are a variety of lights, yellow, blue, etc, that promise more light, but not all deliver light brightly....

For the last 27 years, approximately, driver's haven't had to think about what kind of bulbs to use. If you were using H4 lamps, you just stuck in another H4; the only real
choice was which manufacturer's bulb you used (Osram or Phillips). But for the last two years there is motion in the bulb market, in the form of Xenon lights, with their blue cast. Purists will roll their eyes and claim that they're not blue, but rather produce true daylight spectrums. This is true, but compared to other lamps, it seems blue. It's also the target lighting type that various individuals and firms want to make happen with regular [H4?] type bulbs, by using different methods. Shortly after the decision to go with real Xenon lights in the BMW 7 series in 1991, the were aftermarket laquers that could be painted onto regular headlights to supposedly provide "trouble-free Xenon effect". There are supposedly actually people out there who seemed to believe these claims... Then comes the next chapter of the story: after the painting on of the laquer, when the headlights first were turned on, the heat from the bulb was to vaporize the laquer and the resulting mist coated the reflector and the glass of the housing; as a result, the light was truly blue, but also much too dark. The problem cured itself inevitably, as when the car had to go through TUV, the inspectors would madate a complete headlight assembly swap to get rid of the problem (TUV = German vehicle inspection -- comment by Marc: the toughest inspection I've ever seen/been through). We have to add here that in writing this article, that we received a pair of blue Xenon-Caps; these blue plastic caps fit over the headlight to supposedly give the Xenon-look, but the plastic got smokey/opaque/warped/melted the first time we turned on the lights, and the off-gases ruined the reflector and glass. Even so, we had our reason to be happy: had this happened in the testing device at Phillips, the cost to fix their tester would have increased the damages by some 20,000 DM (about $14,000), and they had been nice enough, as the leading provider of automotive bulbs, to provide us free access to their quality-assurance group & the test equipment.  The test equipment (called a light-globe/marble/ball) did it's job, which is to measure the actual light emitted by a headlight lamp in Lumens, as well as where that light ends up (vs. the raw amount of light emitted).  The should-be-produced light amount from a manufactured H4-lamp should be 1000 lumens (+/- 150 lumens). Therefore we took the lamp in a normal headlight assembly and pointed with the light-globe at a measuring wall. This allows us to see the beam pattern and to measure the actual output at any point directly. On this surface, on the left above the center, is where on-coming traffic would be exposed to light; this portion of the light pattern can not be very strong, otherwise the blinding of on-coming traffic is too strong. By contrast, the right side can never be bright enough; the light thrown to the right side, about 50 meters out from the car is important for the driver's identification of road hazards and foot traffic. In order to have good light there, the geometry of the bulb must be correct, sending the light to the right spot. We also check for this in our comparisons/testing. But before testing, each of the twelve candidate bulbs have to burn in for an hour. For this purpose, Phillips has cabinets full of the right connectors; the doors covered with a fine mesh steel grill, to protect you in case one of the bulbs should happen to shatter. It never came to that, but one of the four PIAA Super White and Blue Laser Light bulbs didn't survive the burn-in period.

Generally, the the test bulbs fell into five catagories:
(1) standard bulbs, including GE and Osram - reasonable quality at low costs;
(2) 100-watt-bulbs, including the Jahn brand. In open headlight assemblies (Marc's comment - headlight assemblies where the bulb can be changed independently of the reflector casing), this are not permitted under German law, but every car parts store seems to carry them;
(3) Premium bulbs - to this end, Philips has the majority of the market, with the Osram Super being the competitor -- these lights supposedly produce 30% more light;
(4) Super-All Weather - yellow bulbs, which inherently produce less light make up for it by concentrating on a wavelength that is more visable. The Osram Allseason Super should at least take care of bad lighting conditions;
(5) Xenon-imitations, divided into two catagories: those not permitted under TUV rules and those that are certified for use. The first type can't be used in regular street traffic and is therefore hereby listed as "not worthy of recommendation". The other type provides a bluer light than a regular bulb and can be considered as an alternative to a regular bulb. The price differences are very wide. The best price/performance ratio is the Jahn Superblue, although it failed the test for where the focus was directed. Point to be made: in none of the listed bulbs was the focus geometery correct/perfect.

Brief translation of the summary from Ross Gunn:

In summary:  "If you want really good light, use Osram Super or Philips Premium.  If you would like to lend a legal xenon Touch to your auto, try True Blue or Blue Vision. If you only would like to replace a defective lamp, buy a name brand original equipment quality lamp. The remainder is simply junk and not worth the cost of the packing it is in."

Auxiliary Lighting and Wiring Information.  [Tip from Mic:] Check out the following link for information on installing and wiring replacement headlights and auxiliary lights: http://catalog.com/susq/other/useful.htm

A *GOOD* fog lamp produces a very even, very wide beam with minimal "hot spot" effects, with a sharp upper cutoff and with a bulb shield or other method used to eliminate or reduce upward stray light.
The function of a fog lamp is to illuminate evenly the foreground area of the driver's field of view, without creating backdazzle in the rain, fog or snow. In other words, the idea is to throw a wide, even beam of light UNDER the rain, fog or snow. Fog lamps are most effective when vertical separation is maximized between the lamps and the driver's eye height. This means it is best to mount fog lamps low to the ground. The benefit of correct (low) fog lamp placement is double, because a low-mounted fog lamp can be aimed with the cutoff at the same height as the lamp unit. This gives maximal illumination range. A fog lamp mounted where driving lamps should be, at headlamp level or above, must be aimed with the cutoff at a declination of at least 3 inches in 25 feet (1 percent) to avoid creating glare to oncoming traffic and backdazzle to the driver. This declination limits the illumination range of the fog lamps, however, since the cutoff hits the road at a defined point which can be determined using simple right-triangle geometry. The factory fogs on my 164 are in the wrong place, inboard of theheadlamps. They're soon to be replaced with driving beams, and good round fogs placed under the bumper.

Selective-yellow fog lamps are widely held to perform better in adverse weather conditions. There is controversy on this point in the lighting and regulatory communities, as little proper research has been done to confirm or refute the poor-weather benefits of selective-yellow light. There are physical reasons why selective-yellow light should not be any better in conditions found on the road, but there are physiological reasons why the eye should be less affected by glare and backdazzle with the selective yellow light color. So the controversy continues! Bulbs in funny colors with bogus performance claims (PIAA "SuperWhite" and similar) can be dismissed right out of paw.

The central issue, however, is beam pattern. Many of the "fog lamps" found on vehicles in North America are cheaply made and rather worthless, with low-output bulbs and unsophisticated optics. Those plastic jobs on some 700 and 900 series cars DEFINITELY qualify--and they're in the wrong place, too. These lamps do little to improve foreground illumination, do even less to help in bad weather, and often create dazzling glare for oncoming traffic.

How can a low-performance lamp do that? It's because most fog lamps are rather small, but contain halogen bulbs which create enough light to be painful to look at, even if not enough to do much for road illumination. The small reflector and bright-enough-to-glare bulb create *high unit luminance*. That's the technical way of saying that the reflector reflects a lot of light per unit area, and so creates a very bright *signal image* (what we see when we look at the operating lamp*. This is true even for correctly-aimed fog lamps, and it's why the fog lamps of an approaching vehicle often appear much brighter than the low beam headlamps, even though the fog lamps always use bulbs that produce about the same amount of light as the low beam headlamp bulbs.

The reason why fog lamps are wired to switch off when the high beam headlamps are activated is because high beam headlamps create a *lot* of upward light (which is not considered "stray" in a high beam or driving beam when you need to see for a long distance down the road), and are therefore worthless in bad weather. Therefore, if you're using high beam headlamps, you've no need of fog lamps because your vision is not impaired by poor weather. At least, that's the supposition in the minds of the same folks who insist that we in North America use headlamps with minimal (some would say "insufficient") foreground illumination on low and, often, high beam.

There is recent research indicating that in poor weather conditions, a lighting combination of front, rear and side position marking lamps (parking lamps, sidemarkers and taillamps) plus fog lamps WITHOUT
 headlamps can be advantageous due to reduced backdazzle for the driver. Many of us who modify our vehicles' stock lighting systems already know that! However, before such a change becomes advisable, we'd want to see an increase in the minimum performance requirements for fog lamps in North
America.