Window Regulator - works then shorts the fuse..

Changed the n/s regulator at the weekend, worked perfectly while I adjusted. Buttoned up the door card and suddenly, nothing, the fuse had burnt out. Took apart and reconnected, burnt through 3 more, instantly fusing. Disconnected the electrical connector to the regulator and the re secured, worked perfectly again. Worked absolutely fine since, then tripped the fuse again this morning. Replaced the fuse, works perfectly again. I've checked the wiring, nothing obviously wrong. There are no screws of fastenings going anywhere near any parts of the loom.... I changed the regular on the o/s in the autumn and have done it before on my 986, normally straight forward... I'm at a bit of a loss? Anyone had this happened to them before?

I guess other than wiring intermittent extra mechanical loading can cause the circuit to demand more current than the fuse can handle. I guess such extra loading may likely be found in the gears and mechanical joints in the regulator and window guides.. :?:

Now starting to get a bit annoying. Worked fine all day, then just went again, spare fuse in the car, put that in and fused it immediately when I put it into the fuse box. Clearly main issue is that the doors won't then close properly. Think I'm going to take it apart again....

Any chance there is an intermittent short at/in the switch.. :?:

Use your key to prove / disprove this.

Just a thought but which fuse is blowing? The label gives at least 3 different fuses for 'power windows'. Is it possible that there is something else on that circuit?

I'm guessing the 3 different fuses will be the 3 different ways of controling the regulator: window switch, alarm, power roof ecu.

Fixed......again....sort of... Stripped the door down, it would then blow a new fuse even as you put the fuse in with the ignition off...which is odd...and then also even with the new regulator 'unplugged'. Re connected the regulator. Tried the window switch, disconnected, re connected, nothing untoward. Put the last (6th fuse) I had in and it then just worked. Went out and brought a box of fuses. Think it might be something to do with the passenger door lock/handle (had the lock changed at a recent service). The issue has happened when a passenger has used the door. Although clearly I've now opened and closed the door from inside and out repeatedly and it still works. Could this be the culprit? Just tried it again, works beautifully, which as everyone who has changed a regulator knows, is incredibly satisfying (although not when the fuse goes...). Will use it all day today and see where I get too as clearly I haven't actually fixed the problem. Thanks for all the replies, very helpful.

My 'fuse booklet' only has one fuse tabled as Power Windows (front) Row D line 1 (Green 30amp). This is the only one that blows. And the windows (both) are the only thing that stops working.

My 'fuse booklet' only has one fuse tabled as Power Windows (front) Row D line 1 (Green 30amp). This is the only one that blows. And the windows (both) are the only thing that stops working.

Fuses blow for 2 reasons .. The item they are powering up is seized , short circuit and it overloads the fuse .. ie too much amperage is drawn trying to operate the item and the fuse melts .. 15 amp fuse and the motor tries to take 20 amps .. you will get a blown or melted fuse .. often a melted one . The other is a short circuit .. ie the positive and negative wires are touching each other .. or the positive wire is touching the body work .. same thing in essence . I'm confused as to why you have issues shutting the door when the window fuse has blown .. enlighten me there please ... window too high perhaps and hitting the door shut ? You have though had the window motor disconnected and the fuse blew .. This indicates a wiring short .. Its intermittent so something is altering to make this happen at times .. To me .. the wiring in the door harness has broken , perished and at times its shorting out ..bit of a pain to get the rubber far enough off of it to check but that's the first thing i'm thinking .. The other ..the door harness is in a big rubber boot that bolts to the door frame .. this is where you unplug the loom if you want to remove the door .. I've seen these incorrectly fitted .. loose shall we say and water has got in .. water and wiring dont mix and cause all manner of issues . From what you have said and what i understand of the issue so far though .. you have a wiring short in the door harness . Just to point out .. this system stays live if a door is open with no ignition key in the lock .. it shuts down after about 5 mins , door open or if the car is locked .

I agree with everything you've said...thank you for taking the time. Yesterday I used the car all day, purposely used the windows all the time and used the passenger door...nothing, no short and windows work just fine. I only suspected that was the problem as the issue re occurred when I had a passenger use that door (rather than use the window). There is obviously something either in the loom or the switch. The loom appears fine, a bit old but fine. Not sure what the issue is, but suspect that it will next appear at the most inconvenient moment...

It's more than likely a fault with the passenger side but if both windows operate from the same fuse .. you have to consider it might be a drivers door harness issue . Bit of a long shot but worth bearing in mind . No .. i haven't looked at a wiring diagram to confirm this , i can if needed , but if 1 fuse for both windows then its both doors that can cause it .

Again, agree. Hasn't happened since. However, intend stripping the driver door down this week to slightly adjust the window regulator on that side (catches the rubber - which I suspect could do with replacing really) and so will have a good look around.

Drivers side re done, nothing obviously there either. Used daily since I appeared to have cured it (just stopped happening) and hasn't happened again. So I'm none the wiser. But thanks to those who offered ideas/help.