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My car has started to fall apart.
OK, that's a bit hyperbolic, but one year into ownership, I've had three issues pop up in rapid succession on my 1995 940 base: Play in a tie rod end, a noisy AC clutch bearing, and now this: heated mirror (just the right one), and heated rear glass stopped working. Not too bad for a car that's nearly 29 years old.
I realize I need to get in there with my multimeter and do some troubleshooting. But I'm wondering if anyone else has dealt with this combination of failure, and can give me a place to start looking. I haven't checked resistance on either element yet, figuring the failure of both at the same time is unlikely, and assuming they are wired in parallel. Of course this is the first frosty morning in half a year, and perhaps they didn't both fail simultaneously. But I'm enjoying typing this in my cozy kitchen, and will venture out with my thinking cap once the temps get into the 40s (was 27 when I noticed the problem--last week saw highs in the 80s, and slept with an open window for two nights, New England for ya).
Thanks as always, Wilson
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Bill and Dave,
I'm replying to both of your responses in one message as some of this is relevant to both of your suggestions, and saves repetition.
Bill,
The wiring diagram you sent made things much clearer to me, thanks for that. An important part I missed is that the timer relay is within the switch assembly. Kind of obvious since the business end of the switch is so much longer than similar dash switches, but I spaced out on that.
Now, with a better understanding of how this system is wired, I'm convinced the two issues are unrelated. Yes, the mirror did work in my test yesterday. The level of heat I felt was real, and consistent with the driver's side. This morning, the RHS mirror did not heat. Much less frost today, but enough. And when I got home from my extremely short excursion of dropping the kids off at school, the RHS mirror was ice cold, LHS warm to the touch.
There's a small possibility that I'm mistaken about the rear glass not working. The mirrors obviously clear in about half the time (making that assumption because the timer shuts off in 6mins vs. 12 for rear glass). I didn't warm the car up very much before driving off--only long enough to buckle my 6yo into his car seat, and scrape the windows (including rear, which I did last, but completely). I'm pretty certain the rear isn't working, since you can usually see at least a little progress soon after switching on the defroster, but I'm open to the possibility I was mistaken. As for this morning, I intentionally left some frost around the edges of the glass, but it was warmer, with less frost, and the sun melted it before I noticed if the defroster was working on the remaining frost.
As for my finding voltage? Well I tested at the bullet connectors after removing the tailgate trim. So voltage seems to be present in the tailgate, but obviously not a guarantee it's making its way to the element itself. I think the connection between the wires and the glass must be under the black trim surrounding the inside of the glass. I'll remove that, and test again. I did measure resistance at the element itself. I don't recall if I measured at those bullet connectors, and I didn't unplug them, so I could have been seeing resistance somewhere else in the circuit. Auto electrics aren't a strong suit of mine.
Dave,
Thanks very much for the detailed instructions on the mirror connections, and more. The RHS mirror did not work (along with rear glass) this morning. As above, I'm of the thought that the mirror and rear glass are unrelated issues. I'm further open to the possibility of my "wiggle / reseat" fix from yesterday was a coincidence. It makes far more sense that there's a compromised connection in the mirror, than in the harness behind the dash. I'm going to follow your advice next. I want to say I probably won't get to this until next week, but I have a feeling I'll pop out for a look this afternoon anyway.
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Follow up to my previous post.
Dave, I couldn't resist, and got out there with my needlenose pliers. The spades were surprisingly easy to access via your instructions. They seemed tight, and did not seem terribly corroded, but were definitely green. I cleaned both sets of spade connectors with PCB / contact cleaner, and tested for voltage while they were drying. I saw voltage at the end of the harness. After they were dry (and looking clean), I put a dab of dielectric grease on, and reconnected. Voila, I have heat at the RHS mirror again. Since I said this yesterday, I'll just wait until the next frost before declaring a victory. Might be a while, the lows seem to be coming up for the next week or so.
So now, the question is do I pre-emptively do the same for the RHS mirror, or leave well enough alone? It took probably five minutes, and I left the tools and materials out, so now's the time to do it... I'm sure I'll get to it this morning, but I should probably do some real work first.
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Always nice when a hunch of mine turns out to be correct, especially when it was such an easy thing to try. If you hang around these forums long enough you pickup stuff like that. I think it was either Spooky Jay, one of the old Steves or Randy who first mentioned that here, probably Spook. Now that you've reminded me, I'll maybe go out and do a proper cleaning of all four of my mirrors. Yes, I would do a pre-emptive cleaning of your other mirror.
As for the rear window defrost, if the light is on in the switch and you don't want to dig into the console then the next stop can be checking for power getting to the rear. Two things you can try and I've done both. I'm mostly familiar with wagon tailgates and it's been a while since I needed to check a sedan defrost grid. It is not uncommon for one or more cross traces of the grid to be damaged and no longer conducting, or else conducting poorly, especially in wagons. If you can steam the glass, even with your breath, then you can visually see which traces are working. Ideal is on a frosty morning and watch it as it warms up or having a crowd of people in the car on a colder, damp day first thing in the morning with the windows closed. Maybe give each an open mug of hot coffee and a newspaper to read with the political headlines of the day to get them really steamed.
It's normally difficult to probe for voltage at the grid or exposed connectors, but well worth a try before needing to remove the side trim to access the connectors for proper testing with a meter. I don't recall that you can probe at the exposed side tabs, leastwise not in wagons.
First you need to find yourself a good chassis ground. The closest screws are usually behind plastic plugs and the screws themselves may be into plastic, not metal, so double check that. The screws holding the door catch are a good ground, but perhaps not so easy to get an alligator clip on and maintain good contact. I forget how far I had to go back to get an alligator clip on a ground point. I may have just taken my 10 foot lead and found something easily used at the rear end or dash
Next is to have a good sharp needle on the end of an alligator clip. Re-sharpen on sandpaper or whatever as needed during testing. Shirt pins easily bend held in pliers, so grab a few pins as spares and grab closer to the tip, careful not to scratch the glass. My preferred weapon of choice is a sturdier T-shaped basting pin stolen out of my wife's sewing kit (I stole two, they now live in my rack of test leads and jumpers).
There's a thick protective clear coat on the grid to prevent damage. They used to have a plastic coating that was more easily probed; the newer seem to be a much harder plastic or ceramic and much more difficult to probe. Probe hard directly into the wider traces on the side near the connector tabs, not the fine traces unless you really need to, wiggling the tip, not scratching. One side will have voltage and the other will be ground, checked by the Ohms function -either figure out which side by trial and error or know that in 700/900s it's normally ground on the right passenger side. If the meter flickers then you've got something and can consider that side of the grid ok.
What often happens is one or more thin traces are either damaged and broken or no longer conduct enough current. If you can visibly see a scratch or damage then that's a potential break. To find and confirm breaks you can use a sharp pin and the Ohms function. The traces are parallel so voltage runs around the break. Resistance to ground will be greater when your probe is on the powered side of a suspected broken trace compared to the same spot on a good trace and you can easily confirm the break by moving the probe side to side of the break. I usually narrow down breaks using two needles working inward either either side of the thin traces rather than using chassis for ground.
Now having said all that, these newer thin traces are very difficult to probe and you risk damaging a thin trace. My preference now is the steamy window approach. If nothing works then it's a either a broken trace at a window side tab connector or a wiring problem to a connector needing to have trim removed to isolate.
There are window defroster grid repair kits with a small bottle of copper metallic paint that you can get at many good auto supply stores. You bridge the gap with paint and let it cure. The problem is you need to scrape the clear coat off, exposing a nice bare original metallic surface, while not scraping it off the glass. I've used these a couple of times with very limited success, and even then it was on the older wider thin traces, not the newer more invisible very thin traces behind a harder coating. I no longer bother trying to repair them as long as a few traces are working -the window will eventually warm and clear. If I ever have a problem near a side connector then I'll try again and research the best repair kits.
Hope that helps.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Thanks again, Dave. I did go out within an hour after my previous post, and attended to the other mirror. While I noted that there didn't appear to be much corrosion, I acknowledge that it doesn't take much. I had opportunity to test the previously ailing mirror a couple of days later, and it's still working. Other side as well (I didn't break it during my cleaning).
So the mirrors are fine. In spite of many older cars not having that feature, I value that more than the rear defrost, since if that needs to be done, I'm almost always having to scrape or wipe other windows anyhow.
And yes, the rear defrost is still not working. After going over the wiring diagram Bill provided, there is obviously no connection between the two, but I was hoping that I may have been wrong in condemning it. The grid seems to be intact. In spite of what you said, mine appears to not have a protective coat. I didn't have to pierce the grid to measure continuity. It's kind of a soft gold in color viewed from the outside, and silver from the inside. Glass is Volvo / Sekurit, dated '94, which is consistent with the car's early '95 build. Or perhaps I'm in error with my diagnosis. I don't see how I could botch a simple continuity test, but perhaps...
I did note 12+V at the bullet terminals hidden under the carpeted tailgate cover. Looking back, I should have disconnected there, and checked for continuity at that point. It would seem to me that the issue lies between those connectors and the glass. But again, perhaps I misdiagnosed...
Regardless of how this turns out, I've seen worse. That's a bold assumption at this point, but anyone whose had to deal with a BMW e61 wagon tailgate would likely agree. On that car, I had to essentially rebuild the harness between the body of the car and where it enters the top of the tailgate. There are even kits for this purpose, but since I was in there with a soldering iron anyhow, I used bulk wire and made it myself. The saving grace on that car was the audio system speakers in the headliner (yes, that's right). Removing the speaker gave access to the harness so I didn't have to remove the entire headliner. I think I had to splice in 11 wires or more. There was a lot going on in the tailgate of that car: external button for the hydraulic lift, button on bottom to close the tailgate when open, solenoid to release the tailgate, button and solenoid for the glass that opened independently of the tailgate, defroster, center, high mount brake light, antenna for the radio, antenna for the keyless entry remote, some functions of the tail light (reverse, and a panic light if you brake extremely hard), license plate lights, maybe part of the tail light, I don't remember, the wiper motor, and maybe something I'm forgetting. A lot was going on with that tailgate. So once I make the time to dig into it, I'm confident the Volvo defroster won't be so bad.
Anyway, this is lower on my list of priorities (for the car, and in general), so I may not get to it for a week or two. Knowing me, the winter will hit, and I'll get tired of having something broken, and will address it with freezing hands. Too bad I didn't leave the cover off, but I can't stand driving a car with interior bits missing.
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Glad that your heated mirror seems to now be working.
For your future reference and to others, one of the common issues with the 700/900 heated mirrors not working or not fully warming is a poor spade terminal connection on the back of the mirrors due to a bit of corrosion. It is after all exposed to the elements. The thing to try is tipping the mirror frame all the way out and the mirror glass rotated all the way out, prying it out a bit with your fingers to make enough of a gap to see behind with a flashlight and access the wires. Get a curved needle nose plier grip on the wire end. Wiggle it partially off the spade terminal, not completely off, wiggle it around then reseat, repeat a couple of times, to see if the heating element now works again. The heat is rather subtle and it takes time to warm. For a longer lasting solution use spray contact cleaner followed by something like DeoxIT conductive anti-oxidant, anti-moisture paste then re-seat. You could try pulling the terminal right off for a better cleaning, but getting it back on working through that narrow gap is extremely fiddly, trust me.
Be careful not to pry the mirror out too much as you risk breaking the plastic mounting. The mirror has a plastic ring on the back that engages into a plastic gimbal. There are two different styles. If you ever need to remove it for replacement then research which one yours is and how to disengage it without breaking.
As a further note on these mirrors, the back of the glass can separate from the rubber coated heating element. This has happened to me twice, both of my '95 940s, both were the left driver mirror and both happened within 6 months of each other -seemed more than a coincidence. It usually hinges out at the top before falling off completely. The first sign of this is noting a vibrating mirror image as you drive. As soon as you notice it, secure with packing tape so it doesn't separate the rest of the way and fall off. The simplest fix is to reattach the back of the mirror to the rubberized heating element. Carefully separate the glass starting at the bottom until you get a hinge where you can flip it out for gluing. Some minor damage to the rubber is okay, but if it really starts to tear then back off and consider injecting glue rather than coating the surface. Clear, marine grade silicone sealant seems the most appropriate here, but is not a good thermal conductor between the heating element and glass. Don't coat the entire surface. Apply a thin bead, just enough to glue it, and do it in a wide pattern so when pressing it on the sealant oozes out thin. I did a W bead pattern inside a large circle to make a thin sealed air space rather that an open air space. It won't heat up as fast, but it seems to work well. Use a 2x4 block sitting on the glass then wrap the mirror tight with bungees for overnight curing. I then used a couple of carpenters F-clamps to squish the sealant down as thin as I could, stopping well short of breaking the mirror assembly. Both reattachments have now lasted a couple of years and the passenger side mirrors have yet to let go.
I am at the stage of needing to more frequently wiggle the wiring so at some point will pop off the glass for a proper terminal cleaning.
If the mirror glass gets broken, there are one or two online web stores that sell unheated mirror glass, sized to fit, that you glue on the face of the broken glass. There's a regular mirror for the driver side and a convex mirror for the passenger side. Some prefer going with a regular mirror on the passenger side, but for the sake of future drivers used to convex mirrors for safer visibility convex is recommended. There's a special glass glue they provide. It's a slightly cheaper option and a much simpler install than a whole new mirror assembly from a wrecker. I haven't bothered to check what's still available in the Volvo parts chain.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Hi Dave,
Do you have long hemostats (8-10-12") in your tool box?
Get them cheap at Ebay.
They come in handy for finicky jobs like that
mirror spade lug. Great to have in the kitchen
if you need to get something out of the disposal.
No way my hand fits in there.
Cheers, Bill
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Update:
I found a wiring diagram for the mirror / rear glass defrost circuit. I couldn't make much sense of it with regards to how the switch fits in. So I started there, unplugging and replugging the switch. I then found the solid black wire going to ground near the taillight (as indicated in schematic) and verified that looked solid. I then removed the tailgate panel, found the wires going to the defrost, confirmed resistance, and also found 13.6v with the defrost on. As for the RHS mirror, I felt warmth.
Of course, I fiddled with the switch before doing the checks, so I don't know if I really solved anything. If weather keeps on trend, I'll be able to do a real world check tomorrow morning.
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Hi Wilson,
OK it's a false alarm for the mirrors?
Search for repairing dead rear window heater elements.
Soon you'll become an artist with brush and conductive paint.
I just sent you 4 pages from the 94 940 wiring book
Same setup as the 93 940
The 95 940 wiring pdf file I have is messed up badly.
BB
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Hi Wilson,
Are you sure that one mirror is working?
You might get lucky and find fuse 10 open.
The mirror and rear window heaters share that fuse.
Funky to have two out of three quit at once.
Look for:
+12 VDC at the blue wire to right mirror to ground.
You must disconnect the mirror connector to measure continuity.
+12 VDC at the yellow wire to rear window heater to ground.
Maybe it's easiest to measure at the at the switch to ground
at the cigar lighter.
The other stuff is unrelated.
Where in New England?
I'm in Boston north shore where I didn't get frost last night,
came close though.
Bill
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Yeah, for sure unrelated. I guess I'm just humblebragging that my old car has been good to me so far. But of course I'm preaching to the choir.
I did check the fuse to no avail. I mean it looks intact--I'll check again with meter. But unless the mirrors are on separate circuits, I'm expecting it to be good, since the LHS mirror defrosts. Plus the lights on the switch (both the mirror and rear) illuminate as normal.
Not with this car yet, but I've had to deal with rodent activity where I live. I occasionally spray some repellant spray (smells like peppermint) in the wheel wells and on the insulation attached to the inside of the hood. They've eaten the foam insulation on my wife's old BMW, and I've seen droppings under the plastic cover that hides the coil packs on both of the T5s we've owned. I've seen them get into the airbox on a Honda, and into the cabin filter on my sister's Golf. My other sister had it the worst: somehow they made it up into the headliner of her fairly new Honda Fit. I've had them chew wiring on yard equipment (I'm wondering if this is what's going on with my 940). One of my vintage Vespas actually had a huge nest under the fuel tank, and their urine (why do they pee where they nest?) rotted out part of the pressed steel frame from the inside. I got it that way--happened to the PO on Martha's Vineyard. Being a New Englander (is Yankee a perjorative?) yourself, you likely have seen similar.
Yeah Bill, we chatted a little last fall when I got the car. I'm in the Hartford, CT area. I've moved around a bit, but always lived in CT. Boston has long been my favorite city (that I've stayed in, at least), but I recently tagged along on a business trip with my wife where we and the kids stayed in the Gaslamp quarter of SanDiego. That was pretty nice too, although we happened to be there during tropical storm Hillary. Oh the irony, because I visit California to get away from extreme weather (and visit family).
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