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'94 940T Dead windshield wipers

R

rstarkie

Member
Joined
Jan 23, 2004
Location
Hamilton, Ohio
I am not getting 12v to fuse #15 (yellow wire) at the fuse block.

I am under the impression that the intermittent wiper relay is only involved when the switch is moved to the intermittent position. I did recently have the fuse block out to bypass the fuse for the blower motor so the wiper failure might be associated with that, but the wires on the underside of fuse 15 are in place.

Does the yellow wire that supplies fuse 15 come directly from the ignition switch and if so does this failure indicate that the ignition switch is the source of the problem?
 
Did you check power from the wire itself, or from the fuse connections in the front? Did you check both wires, and the connection between the two? Unless you have mice, it'd be strange to spontaneously lose power there. It does usually route power to the fuse panel once the ignition is in KP I but you'd most likely have a whole other host of issues if your ignition switch was acting up.
 
Does your blower motor work? That says fuse 16 is getting 12V when the ignition is on and thus fuse 15 should also be getting power. Power goes from the igntion switch to the hot side of fuse 16 (on a black wire) then to the hot side of fuse 15. Fuse 15 provides power directly to the wiper relay (intermittent function), stalk switch (for wipers and washer) and to the wiper motor (park function). It will probably be a bar in the fuse panel that joins the hot sides of those fuses. If no blower or wiper then that suggests you may have disturbed that black wire under the fuse panel or else the ignition switch is having problems. If it's an MTC aftermarket ignition switch then suspect the switch as they're known to be troublesome, sometimes failing in as little as 3-6 months.
 
Rushin said:
Did you check power from the wire itself, or from the fuse connections in the front? Did you check both wires, and the connection between the two? Unless you have mice, it'd be strange to spontaneously lose power there. It does usually route power to the fuse panel once the ignition is in KP I but you'd most likely have a whole other host of issues if your ignition switch was acting up.
Click to expand...
After removing the fuse tray and turning it over I checked for 12v on all of the yellow wires and found nothing. The upper leg of the fuse socket should have 12v with the key on. I just realized that the radio isn't working and that fuse (#14) doesn't have power to the feed side either.

I have never had trouble with mice in my attached garage and there is no evidence of mice in either car that is kept there.
 
945T said:
Does your blower motor work? That says fuse 16 is getting 12V when the ignition is on and thus fuse 15 should also be getting power. Power goes from the ignition switch to the hot side of fuse 16 (on a black wire) then to the hot side of fuse 15. Fuse 15 provides power directly to the wiper relay (intermittent function), stalk switch (for wipers and washer) and to the wiper motor (park function). It will probably be a bar in the fuse panel that joins the hot sides of those fuses. If no blower or wiper then that suggests you may have disturbed that black wire under the fuse panel or else the ignition switch is having problems. If it's an MTC aftermarket ignition switch then suspect the switch as they're known to be troublesome, sometimes failing in as little as 3-6 months.
Click to expand...
Well the blower motor works fine at this point and you may be on to something. I recently had to bypass the fuse 16 socket. The blower motor wasn't working and when I checked the area around fuse 16 it had distorted/melted some. There was one wire feeding the fuse and one wire from the fuse to the blower motor. I cut those two wires and extended them to install a new fuse holder which restored the blower motor function. I performed the replacement after reading about it on the 700/900 FAQ's on the Brickboard. Those FAQ's have not been edited for years but there was no mention of problems with the wipers after doing it.

There is no apparent connection between the feed sides of fuses 15 and 16 so it could be a bar that is hidden between the top and bottom of the fuse panel. After my initial post this morning I have found the radio fuse is not getting power on the feed side either. I certainly can't use the original fuse 16 socket so if in fact there is need for power from 16 to 14 and 15 it will need to be supplied from my bypass fuse wire.

It seems like an odd set up to have individual wires running to the feed side of 14 and 15 if there is a hidden bar supplying 12v to that area.
 
rstarkie said:
Well the blower motor works fine at this point and you may be on to something. I recently had to bypass the fuse 16 socket. The blower motor wasn't working and when I checked the area around fuse 16 it had distorted/melted some. There was one wire feeding the fuse and one wire from the fuse to the blower motor. I cut those two wires and extended them to install a new fuse holder which restored the blower motor function. I performed the replacement after reading about it on the 700/900 FAQ's on the Brickboard. Those FAQ's have not been edited for years but there was no mention of problems with the wipers after doing it.

There is no apparent connection between the feed sides of fuses 15 and 16 so it could be a bar that is hidden between the top and bottom of the fuse panel. After my initial post this morning I have found the radio fuse is not getting power on the feed side either. I certainly can't use the original fuse 16 socket so if in fact there is need for power from 16 to 14 and 15 it will need to be supplied from my bypass fuse wire.

It seems like an odd set up to have individual wires running to the feed side of 14 and 15 if there is a hidden bar supplying 12v to that area.
Click to expand...
Both fuse 14 and 15 are connected to the hot side of fuse 16, which gets its power from the ignition switch on a black, not yellow wire. Connecting fuse feeds under the fuse panel either needs jumper wires (as in multiple wires piggy backed to that black wire terminal), but as I recall it's bars to save space, plus no wire colors are shown between fuses in the green manual wiring diagrams. If that black wire is solidly connected and there's no sign of heat damage in or under fuses 14/15/16 then that's pointing the finger at the igniftion switch. Edit: Just saw your last post. If there's heat damage to fuse 16 then that suggests the problem is indeed with that black wire under the fuse panel. Time to pull the tray.
 
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rstarkie said:
Well the blower motor works fine at this point and you may be on to something. I recently had to bypass the fuse 16 socket. The blower motor wasn't working and when I checked the area around fuse 16 it had distorted/melted some. There was one wire feeding the fuse and one wire from the fuse to the blower motor. I cut those two wires and extended them to install a new fuse holder which restored the blower motor function. I performed the replacement after reading about it on the 700/900 FAQ's on the Brickboard. Those FAQ's have not been edited for years but there was no mention of problems with the wipers after doing it.

There is no apparent connection between the feed sides of fuses 15 and 16 so it could be a bar that is hidden between the top and bottom of the fuse panel. After my initial post this morning I have found the radio fuse is not getting power on the feed side either. I certainly can't use the original fuse 16 socket so if in fact there is need for power from 16 to 14 and 15 it will need to be supplied from my bypass fuse wire.

It seems like an odd set up to have individual wires running to the feed side of 14 and 15 if there is a hidden bar supplying 12v to that area.
Click to expand...
Just saw your latest post. That explains everything. Time to pull the tray and put a pigtail jumper from the black wire you cut to the hot side of either 14, 15 or 16. I've bypassed 940 fuses before and learned to check the neighbouring fuses to see what else is connected. It's really disppointing that those fuse panels have become such an issue for many of us. Cheap ATC fuses may have a higher aluminum content in the legs, allowing galvanic corrosion between the legs and the copper sockets to happen. The copper contacts may also not be designed to be a bit more compatible with aluminum. It's that increased resistance that causes the overheating. Heat softens the copper and makes the grip weaker. Next thing you know the plastic is melting to highlight the problem. The fuses with the higher currents going through them, like the blower and fuel pumps, are among the first to go. I recently bypassed a couple of fuses. I should probably go back and clean up the other fuses in both my 940s before they cause even more problems.
 
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945T said:
Just saw your latest post. That explains everything. Time to pull the tray and put a pigtail jumper from the black wire you cut to the hot side of either 14, 15 or 16. I've bypassed 940 fuses before and learned to check the neighbouring fuses to see what else is connected. It's really disppointing that those fuse panels have become such an issue for many of us. Cheap ATC fuses may have a higher aluminum content in the legs, allowing galvanic corrosion between the legs and the copper sockets to happen. The copper contacts may also not be designed to be a bit more compatible with aluminum. It's that increased resistance that causes the overheating. Heat soften the copper and makes the grip weaker, nextthing you know the plastic is melting. The fuses with the higher currents going through them, like the blower and fuel pumps, are among the first to go.
Click to expand...
Hiding a bus bar is disappointing as well. I did a temporary application of 12v to the old feed side of fuse 16 and as you suggested the wipers came to life. The radio did not (yet) but I'll get to that.
Thanks for your responses.
 
UPDATE:

Everything is back in order after installing the 12v jumper to the supply side of the old fuse 16 socket.

Recently I posted about the SRS light on this car that suddenly failed to go out (https://www.turbobricks.com/index.php?threads/srs-light.380386/#post-6526870) Once the jumper was in place and everything reassembled I realized that the SRS light was once again operating as it should. Somehow that bypass of fuse 16 had effected the SRS circuitry as well as the radio and wipers.
 
945T said:
Just saw your latest post. That explains everything. Time to pull the tray and put a pigtail jumper from the black wire you cut to the hot side of either 14, 15 or 16. I've bypassed 940 fuses before and learned to check the neighbouring fuses to see what else is connected. It's really disppointing that those fuse panels have become such an issue for many of us. Cheap ATC fuses may have a higher aluminum content in the legs, allowing galvanic corrosion between the legs and the copper sockets to happen. The copper contacts may also not be designed to be a bit more compatible with aluminum. It's that increased resistance that causes the overheating. Heat softens the copper and makes the grip weaker. Next thing you know the plastic is melting to highlight the problem. The fuses with the higher currents going through them, like the blower and fuel pumps, are among the first to go. I recently bypassed a couple of fuses. I should probably go back and clean up the other fuses in both my 940s before they cause even more problems.
Click to expand...
I thought everything was finally in order but then yesterday I realized that the windows would not operate. The ashtray fuse guide indicated that fuses 8 and 9 are involved in their operation. A quick check showed the fuses were fine but fuse 8 (30 amp) socket was not powered. Any clues as what to do before I once again pull the fuse tray and have a look?
 
I was thinking of this thread today as I looked at my 1990 740 GLE fuse block label on the back of the ashtray. I noticed there are red lines on the label indicating which fuses have a "bus bar" or common power source.

You need a good wiring diagram. They can be found if you look around. I have a thread that has some links.

ZVOLV

Thread '1990 740 GLE 16V. Check engine light, rough start and low rough idle. Intermittent crank-no start.'

I just bought this car and giving it the shakedown.



--------------------------------------------------------------------------
FIXED!!!!!!

UPDATE 3/24/2026- I have been driving the car for months now with no issues. No stalling, no idle issues, no check engine light.




$3 test lamp, $20 terminal test probes, $5 noid light, and free wiring diagrams (thanks again). These tools have currently lead me to the diagnosis of the issues as:

1. PCV hose air leaks
2. torn FPR hose
3. degraded RSR wiring
4. LH box throwing fake TPS code and intermittently not operating the LH/fuel...
  • Like
 
ZVOLV said:
I was thinking of this thread today as I looked at my 1990 740 GLE fuse block label on the back of the ashtray. I noticed there are red lines on the label indicating which fuses have a "bus bar" or common power source.

You need a good wiring diagram. They can be found if you look around. I have a thread that has some links.

ZVOLV

Thread '1990 740 GLE 16V. Check engine light, rough start and low rough idle. Intermittent crank-no start.'

I just bought this car and giving it the shakedown.



--------------------------------------------------------------------------
FIXED!!!!!!

UPDATE 3/24/2026- I have been driving the car for months now with no issues. No stalling, no idle issues, no check engine light.




$3 test lamp, $20 terminal test probes, $5 noid light, and free wiring diagrams (thanks again). These tools have currently lead me to the diagnosis of the issues as:

1. PCV hose air leaks
2. torn FPR hose
3. degraded RSR wiring
4. LH box throwing fake TPS code and intermittently not operating the LH/fuel...
  • Like
Click to expand...
Thanks for the heads up. I'll have a look for that information on the ashtray. Auto electrics has always been a weak point for me. I have the Volvo Green Book for 1994 940 wiring but find it hard to interpret.
 
rstarkie said:
I thought everything was finally in order but then yesterday I realized that the windows would not operate. The ashtray fuse guide indicated that fuses 8 and 9 are involved in their operation. A quick check showed the fuses were fine but fuse 8 (30 amp) socket was not powered. Any clues as what to do before I once again pull the fuse tray and have a look?
Click to expand...
Start by checking to see if the right front passenger door switch can operate its window. If it can then it's not the fuse panel or the power window relay, it will be a broken wire in the driver door, likely in the hinge area.

Otherwise, it's back to your favorite fuse panel and relay tray. Start by checking all of fuses 8, 9 and 23. Now with ignition on (KP-II) probe into the top of those fuses to see if any of them have 12 volts. ATC fuses have slits on the top for meter testing with a narrow probe so you don't have to remove the fuse. The cigarette lighter black wire is a convenient source for meter ground.

Odds are if none of the window switches work then you won't find power on any of them, indicating its once again a problem under the fuse panel or under the relay tray. If you do find power on any of them then that can help narrow the possibilities.

Power comes from the ignition switch on a yellow/black wire to the hot side of fuse 10 with an internal bus bar over to fuse 9. Fuse 9 provides power for the window relay (a blue/green wire under the tray). The relay is always engaged (closed) when the ignition is on to provide power to the window switches. The relay load circuit passes battery to the hot side of fuses 8 & 23. Fuse 8 is power for the driver door window switch pod switches and the passenger door switch which then pass power to their various power window motors and the rear door window switches. Fuse 23 is for the heated seats, so let me guess they don't work either (although the seat heaters have their own issues, especially the leather seats).

If you've got the '94 green electrical manual then try to follow this as much as you can. The more you use it, the easier it gets. The Volvo green manuals are well done and much easier to use than schematic wiring diagrams from the likes of Haynes and Mitchell.
 
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Passenger's door window inoperative along with the others. I have power to fuse 9. There is no power to fuse 8 or 23. I swapped the relays from our other 940t and both operate the windows in the second car.

On the car with no power to fuse 8: The socket for the relay only has power to the 30 terminal, while the car with functional windows has power to both 30 and 85. So I guess the question is where does the power to 85 come from?
 
If you've got power from the ignition switch at fuse 9 and none on 8 or 23 then it's at the relay tray. Given that the relay works in your other car, it's in or under the relay tray. Relay pin 85 should be seeing volts from fuse 9 through the relay coil when the relay is in place, but no volts in the socket when the relay is removed. It would appear your problem is with the green/blue wire between fuse 9 and relay pin 86. Check to make sure the pin 86 terminal in the relay socket isn't loose and got pulled or pushed down when you were playing with the rats nest underneath. Also check for a good ground in the pin 85 socket.
 
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I would like to think the problem is solved... but I have been wrong before. Everything seems to be in working order at this point. The fault is embarrassing.

After removing the relay tray and turning it over I immediately saw a small gauge black wire that was cleanly cut in two. Apparently when I had clipped the wire tie that was around the bundle of wires I had cut through the small wire as well. I had removed the wire tie to get some slack to make the addition of the auxiliary fuse holder a bit easier. I did not notice the severed black wire when I put a new tie on the wires.

Thanks very much for your help.
 
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