Power window and sunroof issues - 1996 850 GLT

[ZionXIX]

I would not put a higher capacity circuit breaker. You may exceed the rated amperage for the wiring and cause a fire. We don't need that. As others have stated I would recommend pulling all 4 door panels off and physically disconnecting the window motors from there. Then recheck the CB for heat and so forth.

[npexcept]

No good results from unplugging the switches, but that does seem to narrow it down further to the area below 11/37 and above the master switch.

Could you please again list, what you have tried?
Unplugging all switches, motors, connector 24/20 (?)

Essentially, what's the best way to track down this short? How do I tell that it is a short when/if I find it? I'm a little hesitant to buy a thermal cam just yet, since I think this'll be the only thing I use it on for a good long while, but I will buy/rent one if that seems to be the only route.

Thermal cam would def. be the easier option, a hot to the touch CB would also mean a cable thats at least a degree warmer.
This would show up on a thermal cam. An alternative would be a current clamp (make sure to get one that is DC capable and not just AC).
You can get a decent one starting from 30 bucks. Then you just have to clamp it around a single wire (not multiple, that would maybe cancel out the readings!) and check, where a lot of current is flowing and try to follow its path.

For example I believe it currently has a 12v 20a CB in it right now, would a 30a be helpful?

This wouldn't help. A hot CB means there is a lot of current flowing, which will also drain your battery like crazy. So this has to be addressed.
The wire gauge and motors is also rated for these 20a, so with a bigger fuse, you would only risk a cable fire. The CB is there to melt in case of overcurrent instead of the wires and switches.

[Didntchaknow]

Can do! Currently, we have tried:
-switched out old CB for new
-tested new CB, confirmed working correctly
-disconnected master switch
-disconnected motors on all doors
-disconnected window switches on back doors
-disconnected sunroof connector (24/20)
Not necessarily in that order.

I have not tried:
-testing voltage (need to pull out my voltage tester)
-unplugging the sunroof switch on the dash (not sure if this would be helpful at all)

I like the idea of the current clamp. I would probably use that in more applications that just this, so if I can find one local I'll roll out and grab one today. Would you recommend following the wires from master switch up or 11/37 down?

Definitely glad I asked, I'll try not to start any electrical fires hah.

[npexcept]

-unplugging the sunroof switch on the dash (not sure if this would be helpful at all)

This switch seems to be 3/25 on the diagram. It is supplied by a different fuse (11/35).
So no fault here I guess.

I like the idea of the current clamp. I would probably use that in more applications that just this, so if I can find one local I'll roll out and grab one today.

Yeah they're handy. Sometimes nice to measure currents "non invasive". With a multimeter you would need to cut the wire to measure currents. The downsides are, clamps are not that precise. But good enough for this case.

Would you recommend following the wires from master switch up or 11/37 down?

I would start at the battery, so you also know your the base current draw (for whole car).
Then 11/37 and approaching til you end at the motors.

[Didntchaknow]

Perfect, thanks again! I'll get one this week and mess around with it when the weather's good. Harbour freight has em for cheap and I think it'll be good for the toolbox.

Ill be back with questions on use if anything else comes up.

[BEJinFbk]

Perfect, thanks again! I'll get one this week and mess around with it when the weather's good. Harbour freight has em for cheap and I think it'll be good for the toolbox.

Ill be back with questions on use if anything else comes up.

Remember to look for a DC ammeter.
An AC ammeter is just a paperweight
for automotive work.

[Didntchaknow]

Back again with more info!

My lack of knowledge with electronics is making itself known. Today I purchased a nice quality current clamp from a local shop with ac/dc capabilities.

Using a few different diagrams from the manual as reference, Im attempting to narrow down the location of the short or draw.

Here's what I started with:




I'm following 11/37 down to the master switch 3/97 (which is still unplugged). I started by measuring below 24/2, because it's the most reachable (ish.) All readings are being taken while the car is running.



I wasn't able to measure above 24/2, not sure how to access that. Here's the reading for 24/2, A(2), which is a blue wire, coming from the green twelve pin plug on the white middle box underneath the steering wheel.



It reads -0.28a while clamped? Seems weird. For reference I have the meter oriented correctly (positive in negative out) and the reading off the battery was ~+4.4a so I'm not sure what this negative reading means. Draw?

For further context, here's the reading from another wire in the same area:



It reads 0.33a (positive). I would assume this is a healthy reading? I got a similar reading from a few other spots.

Additionally, I also took a reading from the sunroof connector further down the line to see if any current was making it down there. I used the same (I think) blue wire and got this reading:



Seems like nothing is making it down to the connector?

This connector is in the glove box, and I wanted to test connector 23/412 which is near the glove box as well, as that's the direct path from 24/2, but I wasn't sure if it was actually accessible from the glove box or if I needed to do a full dash dissambly to access it so I let that be.



I also could test connecter C/CK, but I'm not sure how accessible that is either.

All together, I'm not sure if these readings mean anything. If they're nonsense, lemme know and I'll reread the meter manual a few times and take some more readings.

Do I need to go digging further to access different connectors to test? Is this gonna require that I disassemble the dash? Any advice for that adventure if so?

I look forward to your inputs! This is all very new to me and your knowledge is priceless lol.

[Didntchaknow]

I wasn't able to measure above 24/2, not sure how to access that. Here's the reading for 24/2, A(2), which is a blue wire, coming from the green twelve pin plug on the white middle box underneath the steering wheel.



It reads -0.28a while clamped? Seems weird. For reference I have the meter oriented correctly (positive in negative out) and the reading off the battery was ~+4.4a so I'm not sure what this negative reading means. Draw?

I've come to the conclusion that this negative measurement IS nonsense. Here's the one I did today -

Below 24/2:


However, I still don't know what this means.
I also got a reading above 24/2 (didn't get a good picture) but it read 0.14a.

[npexcept]

0.3A or 0.6A is much for not pressing any buttons.
Can you try to follow the wire thats running the most current?

Negative should not be possible in this case, so maybe just the current clamp was flipped.
Just discard the minus.

[Didntchaknow]

I'll give that a try tomorrow, do you recommend following the current up or down?