92 240 dash, tail and brake lights out at once

[haroldburbank]

have 92 240 wagon. recently tail, brake and dash lights failed at once. suspect bulb failure sensor, which was replaced a year ago when that harness showed melting and low beam headlights failed. now no power to tail lights (volt meter tested). curiously brake light circuit shows power but lights wont come on. all fuses checked and good. good power to relevant fuses (volt meter). tested bulb failure sensor harness. no power when tail light switch off. power to 'lamp failure' female node with lamp switch on. curiously the harness ground wire node has power with tail light switch on (sensor removed from harness). there must be a short, possibly in the cargo door hinge harness. the current bulb failure sensor appears fine. no change when i installed a spare. theory 1: slightly melted bulb failure sensor harness has a short. never found why it melted, it has worked since melting without obvious defect. theory 2: cargo door hinge harness shorted. did not check yet. i see no direct connection from this harness to the tail lights. can a short in the hinge harness feed back to the tail lights via the brake light system? the hinge harness serves the rear window brake light which of course ties in to the entire brake light system. comments? thank you.

 

[bobxyz]

If you haven't found it already, there's a 1993 wiring greenbook available at ozvolvo.org/archive/

With the tailgate open, you may be able to see damaged wiring within the hinges. I forget which circuits run through which hinge. The ones of interest for your failure are the 3rd brake light and the license plate lights (tied into the tail lights).

When you say "curiously brake light circuit shows power" where are you measuring, is this with or without brake pedal depressed, and what was the voltage?

When you say "curiously the harness ground wire node has power with tail light switch on" where are you measuring this?

 

[haroldburbank]

thanks for green book idea. will seek. seen some pages on the net.

with tail light switch on and brake light pedal not depressed test light fires on ground node of bulb out harness (sensor removed). this female node is #8 on a standard harness textbook diagram. voltage not measured, test light only. inserted in the #8 female node of the harness. no power to this node with switch off (normal), just when switch on.

have yet to pull tailgate hinges. an outside and inside car visual does not show wires or damage. cannot see wires without removing hinges.

i am not an electrician. at best an intermediate skill DIY driveway mechanic (of probably 45 years experience on many cars, trucks, 2 tractors, outboards, small engines etc). dad taught me well. loved cars (and probably a mechanical genius. my brother is a pro mechanic in own shop). dad gave me this very reliable 92 240 wagon in 96. very few repairs over 345,000 miles driven by me (420,000 + total miles). much routine maintenance by me thus its longevity. runs well still. would like to see if i can get to 1 million miles. rust will probably control. anyway this is the first confusing electrical problem ive had with it. as stated, the bulb out sensor got hot a year or so ago and partly melted the harness. rescued that in time to keep using it. all wires and hardware intact and able to receive new sensor. the tailgate brake light quit some time ago. at least 1 license plate light went out then, and both are out now. there is constant power at #7 brake light fuse (normal) and power to the brake light circuit all the way to driver's and passenger side brake lights when brake depressed. #16 parking lamp fuse is new. no power to the rear tail lights at any time, switch on or off. obviously a dead short in that circuit somewhere. dash lights are out.

strange to me that there is power to the bulb out harness ground node with no sensor in the harness. the power is there only when the tail light switch is on. i think that means power is feeding back to that node from a shorted light circuit. which 1? how to trace?

i use the car as a truck for dump runs and hauling tools for property work. i need it running this week so im hot wiring the tail lights to fuse #16 as this is switched and illuminates the tail lights in my hot wire tests. will route the brake lights to the fog lamp sockets. this is recommended by mechanics even for 'normal' 240s since in 92 wagons factory power for tail and brake lights runs to 1 bulb leading to socket melt and bulb failure. you can swap the positive brake and fog lamp leads between the respective sockets and get red brake lights from the fog lamp sockets and fog lights from the tail lights.

if this works for me i still must illuminate the license plate lights and the tailgate brake light too. still testing for that fix.

thank you for your comments. please keep them coming. all ideas will be appreciated and most likely applied.

harold burbank
canton CT

 

[bobxyz]

"dad gave me this very reliable 92 240 wagon in 96. very few repairs over 345,000 miles driven by me (420,000 + total miles)" That's great!

"there is ... power to the brake light circuit all the way to driver's and passenger side brake lights when brake depressed" The short taillight ground wires are notorious for failures - do your turn signals still work normally? If so, the brake light bulb holder and/or taillight circuit board are suspect. With the brakes on, try wiggling/turning the bulb holder and see if it lights up briefly.

The tailgate cables have connectors hidden in the headliner by the hinges. They're easy to get to once you've removed the corner of the headliner. See IPD for replacement cables and instructions. The headliner has a ~1/2" wide strip of plastic sewn into the outer edge. This gets folded over and inserted into a channel that runs all around the roof. You can pinch the headliner and pull back/out to unseat the strip from the channel.

Fuse #16 also feeds the dash lights. It's common for it to blow out due to the light in the parking brake lever console to fall out and short to ground. Since you have voltage on fuse #16 but no dash lights, I'd try your test light on the back of the dimmer.

Pin #8 of the bulb failure sensor should be a direct connection to ground. Getting voltage on it at any time is bad. There's a drawing on pg 11 of the '93 greenbook vaguely showing the ground wire path - sensor to steering column, then to chassis tunnel. It's not unusual for the steering column or tunnel connection to corrode. A funny symptom of this is if you honk your horn and the rear wiper cycles.

 

[haroldburbank]

"dad gave me this very reliable 92 240 wagon in 96. very few repairs over 345,000 miles driven by me (420,000 + total miles)" That's great!

"there is ... power to the brake light circuit all the way to driver's and passenger side brake lights when brake depressed" The short taillight ground wires are notorious for failures - do your turn signals still work normally? If so, the brake light bulb holder and/or taillight circuit board are suspect. With the brakes on, try wiggling/turning the bulb holder and see if it lights up briefly.

The tailgate cables have connectors hidden in the headliner by the hinges. They're easy to get to once you've removed the corner of the headliner. See IPD for replacement cables and instructions. The headliner has a ~1/2" wide strip of plastic sewn into the outer edge. This gets folded over and inserted into a channel that runs all around the roof. You can pinch the headliner and pull back/out to unseat the strip from the channel.

Fuse #16 also feeds the dash lights. It's common for it to blow out due to the light in the parking brake lever console to fall out and short to ground. Since you have voltage on fuse #16 but no dash lights, I'd try your test light on the back of the dimmer.

Pin #8 of the bulb failure sensor should be a direct connection to ground. Getting voltage on it at any time is bad. There's a drawing on pg 11 of the '93 greenbook vaguely showing the ground wire path - sensor to steering column, then to chassis tunnel. It's not unusual for the steering column or tunnel connection to corrode. A funny symptom of this is if you honk your horn and the rear wiper cycles.

thank you very much. very kind of you to give so much advice.

please describe where in steering area i can find grounds to check. i will look of course but my eyes are not great today (retired) so i miss some things.

i am making new ground wires for all tail light connections. suggested on youtube. i see no obvious wear on the bulb sockets/holders but i will check further and apply the 'wiggle' test. the turn signals are working and never stopped (so far). i removed both tail light assemblies for inspection and board cleaning. these are not circuit boards but the old school metal frames inserted on volvo light assemblies to which L clips are attached as male plugs for hot wires (tail lights, stop lights, signal lights, fog lights). the rest of the "board' grounds the sockets and bulbs via the ground wire to mentioned. the wires and volvo connectors look ok but they are so old i am hard wiring each bulb socket to their hot wire feeds, and hard wiring each socket to the true frame ground (not the board). recommended on youtube.

still betting the tailgate hinge wires are involved in a feedback problem. i will check the parking brake area. the plastic shielding mine was damaged years ago. will check lights and wires there. that light has not worked for years. i

an 85 240 turbo wagon i had years ago presented a short issue and went away when the hinge wires got replaced. it's a very hot day here today. i work in the no shade driveway so may wait to check these wires when its cooler. plus the tailgate is heavy and awkward to move unbolted. this may not be necessary if all wires are accessible from inside as you described, but for my 85 turbo wagon i had to remove the hinges.

will keep you posted on my progress. any new ideas gratefully accepted. thank you for your help.

 

[dl242gt]

Yes, you have to remove the hinges on all 240 wagons to replace the tailgate wiring harness. It runs through the hinge. One thing that also breaks in the hinge is the ground wire that connects each half of the hinge. You can get strange circuit feedback when the ground is broken. There is one in each hinge. I usually drill the pot metal inside the hinge and use some eyelet terminals with small sheet metal screws to connect a replacement wire. When the ground wires were bad in my 93 wagon it caused the rear defrost switch to dimly light up when hitting the brakes.

The problem Bob mentions with the horn causing the rear wiper to wipe was exactly the problem an old friends brand new 93 wagon had when he picked it up. Of course the dealer had nothing, they couldn't figure it out.

 

[bobxyz]

Sorry, I was suggesting dropping the headliner corners to disconnect (and tape off) the cables so that they shouldn't cause problems. You still need to remove the hinges to install new cables.

Here's the greenbook drawing and a picture of the column-to-tunnel ground wire. Before removing/cleaning the ring terminal, you can try your test light between a good ground and the column pot metal to see if the ground wire isn't making good contact.





Hardwiring the tail light bulbs is a good idea. Next time the lights on my '85 wagon misbehave, I hard wire them.

 

[haroldburbank]

thank you dl242 and bob. today for some reason there is no brake light power with pedal depressed. this worked days ago. now faced with pulling the tailgate hinges and re-wiring there (assuming this is the cause) or hot wiring brakes and tail lights. assume i can fix hinge wires or make my own harness to save time and money. we will see. not yet sure how to hot wire the brake switch if i choose to. ideas? thank you.

 

[haroldburbank]

have a look at this brilliantly elegant modification for 240 tailgate wiring solving hinge cutting of this wiring forever...https://www.youtube.com/watch?v=QhP90OISZXo. note the factory hole on the tailgate used in vid to route wires away from hinge and inside the car through ribbed rubber insulator tubes. the vid example is for a 1980's 240. on my 92 240, the tailgate hole rests between the tailgate and the car frame frame when tailgate is closed (perhaps this is true for all 240s and the vid make did not care). i did not want my mod to pinch the wires between the tailgate and door frame so i drilled a hole in tailgate down toward the tailgate glass and inside (by about 1 inch) of the factory hole. this wire routing placement avoids any wire pinching. the drilling was easy. the tailgate sheet metal there is thin.

i found the passenger side tailgate hinge harness wires broken as suspected. the driver's side hinge wires appear ok so far but i have not removed the hinge yet and will do so to be certain of harness condition. i am betting the broken wires found are keys to fixes to problems discussed above. question: where can i find a diagram showing how the tailgate is wired? the broken wires appear to run down the frame of the tailgate some distance before reaching their accessories. since ive gone this far id like to pull all the old tailgate wires and install new ones. look forward to comments.

 

[Khrrck]

have a look at this brilliantly elegant modification for 240 tailgate wiring solving hinge cutting of this wiring forever...https://www.youtube.com/watch?v=QhP90OISZXo

I did this when I replaced my tailgate harness on the gray 245 and it still had wiring issues. It's not as attractive IMO but looks reasonably factory if you find a nicer loom material to cover it than the YT guy is using. And it does work well.

 

[dl242gt]

Replacing the tailgate wiring isn't that bad. I think it's kind of cool that it was hidden in the hinge.

 

[Khrrck]

Yeah, if I had to do it again I'd have done it properly.

 

[bobxyz]

question: where can i find a diagram showing how the tailgate is wired?

I haven't seen a detailed diagram for this. You might be able to piece together enough info by looking at the pictures for the replacement Volvo and Aftermarket "tailgate harness" from ipdusa.com. You can also look at the 1993 wiring greenbook from ozvolvo.org/archive/ for brake lights, number plate lights, and tailgate wiper - it should be close to your '92.

 

[haroldburbank]

thanks bob. will seek. i pushed my hand inside the tailgate toward the right hinge seeking the broken wire harness. i could not reach it. so far i cannot get a light or my eyes in there far enough to see everything. i tugged on the harness at the hinge and felt no movement on wires in the tailgate. will keep poking at the interior tailgate frame. have to hit a wire eventually. dont want to pull hard and break wires - yet.

 

[Khrrck]

It's very very unlikely it broke inside the tailgate. They break inside the hinge. To replace them you need to unbolt and remove the tailgate from the car after disconnecting the harness above the headliner.

 

[haroldburbank]

yes no wires broken in the tailgate. only in passenger side hinge so far. i finally removed through the tailgate the length of harness that broke off at the hinge. no wire damage other than at the hinge. considered replacing this section but it was solid so reinstalled routing through the holes i drilled in tailgate so wires go to cargo bay and not the hinge. will splice this to the rest of the harness running toward the cockpit. as expected the ground wire on the hinge was cut clean through. that has to have caused some of the shorts. will ground the repair to the body. i will feel lucky if this area is the only problem source. will test tomorrow. thanks to all for their comments and info sources.