Power door lock fuse blowing

So if I push the door lock button on the keys the 20amp mini door lock fuse in the engine bay blows instantly. However, if the drivers door is open and I push the lock button I get no door locking but the fuse does not blow. Everything was working fine and then suddenly this.

 

Sounds like a bad door solenoid.

I think when the door is open, the BCU (body control unit) won't trigger the solenoid when you press the keyfob button.

With the door closed the BCU tries to actuate the lock and the solenoid is bad so it blows the fuse. The fuse is blowing because there is a short somewhere to ground.

 

So getting a little further along. When a new fuse is in place and all the doors are locked I can unlock all the doors with the key fob or the unlock buttons inside. Fuse doesn't blow. Once all doors are unlocked if any door is open and you press the lock button there is just a continuous beep until I hit unlock on the fob. I think this is normal. But once all the doors are closed and lock from the fob or inside is pushed the fuse blows instantly. So is this most likely a bad solenoid in one of the doors or a short to ground somewhere? I checked all the wiring in the drivers side footwell under the dash and inside the drivers door sill. Nothing looked bad.

 

Yeah, a blown fuse is almost always something shorting to ground. Either a wire or a solenoid in this case. If you have an aftermarket security or alarm systems or really anything aftermarket wired into the vehicle, disconnect. Those often are wired into the door solenoids and cause issues.

It could be any one of the 5 solenoids. You have 4 doors and the 1 hatch.

Most likely if it's not a driver's door, it's the hatch. The hatch wiring on the 3rd gens is very prone to breaking after 20 years...probably same on the 4th gens.

I got a stroke reading this: "But once all the doors are closed and lock from the fob or inside is pushed the fuse blows instantly"

Can you reword it so I understand exactly what you mean?

 

Sorry about that. Was typing in a stream of consciousness mode and sent before looking it over. Basically, the door locks open with no problem. When I manually locked and closed all the doors and then put in a new 20 amp fuse and hit unlock, 1 push on the fob unlocks the driver door and 2 pushes unlocks everything, just like it should. Unlocking works using buttons inside too. It's locking that blows the fuse. Whether from the fob or using the inside buttons. I do have aftermarket Rostra seat heaters installed but I disconnected everything and still had the same door lock issues. And after the fuse blows the seat heaters still work fine.
One other thing I found that I'm not sure if its normal or not is that if I leave any single door or combination of doors open and hit the fob lock button I just get a continuous beep that doesn't stop until I hit the unlock button on the fob. The fuse doesn't blow since it seems the ECU is not letting the lock function operate. Since I'd never run into that scenario before until I started trying different things out I wasn't sure if that was a normal function when a door is open and the lock button is hit on the fob or not?

 

Oh, that's weird and yeah, you needed to be clearer. I make it a rule to never post from a phone.

So only locking blows the fuse?

If the door actuators are like the one in the video below...there are some issues that can happen if a diode fails. If it fails and becomes shorted, I could see that happening for only locking.

My next step would be to disconnect the door actuators and verify the fuse no longer blows.

https://www.youtube.com/watch?v=8OGjMrjvQc0

 

So what I am wondering before I start tearing apart the doors and checking actuators is: 1) I would need to disconnect 1 door actuator at a time and then attempt to lock the doors after each actuator is disconnected. If it is a bad diode/actuator, once the culprit is unplugged the other doors should all lock as normal with no fuse blowing. 2) If I do step 1 for all the doors and the fuse still blows then it would almost have to be a ground to short somewhere in the door lock wiring?

 

You need a wiring diagram to know for sure. But I assume these are all 2 wire actuators. You said unlocking won't blow the fuse. If it was a short in the wires, then I don't see how that could happen. The fuse would ALWAYS blow when locking OR unlocking. Otherwise it would be the BCM has gone bad as it is the only other thing that may do something different when unlocking or locking.

Of course, car circuits always surprise me.

 

So today I took each door panel off one at a time and with each panel off unplugged the connection to the actuator and then hit the lock button on the key fob. For all 4 doors the 20 amp door lock/unlock fuse blew when I pressed lock on the key fob. I did not attempt the rear hatch yet. I still need to look into what I need to do about gaining access to actuator/mechanism used to unlock and lock the hatch. I guess that will be next up. Just like before the unlock button works as it should and the fuse doesn't blow. I have a schematic of the entire wiring system for the door locks but I'm not that great at deciphering everything going on in those diagrams. My thinking was that it would be a bad door actuator and once I had unplugged the bad one and tried locking the doors the fuse wouldn't blow since the bad actuator would not be getting any current. Is there a different way I should be going about trying to figure this out?

 

You're narrowing it down. The rear
hatches are notorious for broken wires in the harness. At some point disconnecting things has got to stop blowing fuses.

You really want a wiring diagram. If disconnecting the hatch doesn't stop blowing fuses... You'll need to see where to look next.

 

You must be going through quite a few fuses...

And yes, the continuous beep when a door is open and you hit the lock button on the fob is normal.

 

So, I removed the the rear hatch plastic cover, disconnected everything and still blew the fuse when locking the doors. Unlocking worked just like normal. And yes, I'm going through 20 amp mini fuses at a pretty good clip. I'd guess I've gone through at least 10 now at this point. Is it possible that there is more than 1 bad door actuator and I would need to start by disconnecting all the door actuators and then work back using different door combinations until I find the ones that are bad? I'm trying my hardest to avoid taking it somewhere and have a shop spend hours trying to trace it down at god knows what cost. I would be looking harder for a bad wire making a ground too short but the doors unlocking seems to eliminate that possibility. If anyone has any outside the box ideas or realizes something stupid that I am just overlooking I'm all ears.

 

You need a wiring diagram to see what is on that circuit.

You simply can't diagnose electrical problems on modern cars without one.

Although unlikely, I would still disconnect ALL the actuators. and test.

It's pointing to a bad wire or the BCU has gone bad. I googled and don't see your problem out there.