Essentially what the problem is automotive electronics will typically work down to 8 or 9 Volts depending on the device. What happens when you have a faulty ground is you have a ground wire that is a voltage above 0 Volts in relation to the battery ground due to the basic laws of electricity. When that happens things still work because when you take the 12V from the battery positive and subtract the say 1V that the ground is floating at you still have a difference of 11V. Now in the case of your alarm if your alarm ground is at 0V, but due to a ground problem the door switch ground only goes down to 1.5V then the alarm is not seeing the 0V it expects and your alarm is not arming. I am not saying this is exactly what happened, but as a general rule this is what happens in these cases. The chance of actually finding the problem by measuring things is pretty low due to the fact different loads affect the problem in different ways. The ,moment your alarm checks the switch may cause a slight rise in the ground plane enough that it doesn't see what it expects. Further complicating matters is that face that meters are not fast enough to pick up instantaneous changes that will affect the problem so the .00000001 second blip in the ground plane could be all that is keeping the wipers from turning off as they should, the alarm from arming as it should, or a myriad of other things that are supposed to happen but don't.

That is why everyone is harping on the grounds. We have all been there and I can personally say on more than a couple occasions had a baseball bat or large hammer been within reach the problem would have been solved differently.

Edit...

Another problem that can arise is devices try to ground themselves through the grounds or sensors of other devices and skew sensors and data to the point it looks like the problem is something that is not. I know of a dash cluster in a vehicle at work that all the gauges will go up a little when you turn on the headlights if the gauge cluster ground is weak due to the gauge lights grounding through the sensors instead of the normal path.

Very interesting. I'm in the engine bay and have found and taken the wires from and cleaned and reinstalled 4 different grounds. Up until yesterday I didn't know that on DC circuits the ground actually has voltage running through it ,as it should to complete the circuit, interesting. I want to install an additional ground wire to the ground wire of the wiper circuit? To the best of my knowledge this would prove or disprove a ground issue? What are thoughts on this? I will be in touch with some pics. Thanks

 

@John La just to make sure I understand it correctly.... if you pull the fuse at the moment the wipers are parked they stay off when you put the fuse back in until you turn them back on right? I believe that is the way we all are seeing what is happening when you say they don't park. If it is the case where they turn on no matter what then I have to apologize myself for misunderstanding the problem and chances are they are getting power from somewhere it shouldn't be.

 

As a temporary fix to the problem of having the wipers not turning off after being turned on I have a fused toggle switch connected to the wipers fuse location with the fuse removed. When I turn the wipers on by factory dash mounted switch they will not stop even if that wiper switch is in the off position. Unless I kill the power to them by pulling the fuse/using the toggle switch . At that point with no power they freeze where they are. With the factory wiper switch in the off position I then use the toggle switch to put the power back on, it is then they return to their park/resting position as they should and the power is still on at that point.

 

As a temporary fix to the problem of having the wipers not turning off after being turned on I have a fused toggle switch connected to the wipers fuse location with the fuse removed. When I turn the wipers on by factory dash mounted switch they will not stop even if that wiper switch is in the off position. Unless I kill the power to them by pulling the fuse/using the toggle switch . At that point with no power they freeze where they are. With the factory wiper switch in the off position I then use the toggle switch to put the power back on, it is then they return to their park/resting position as they should and the power is still on at that point.

Is that after adding the ground that you mentioned?

 

Automotive ground issues usually manifest as random nonsense and/or witchcraft. Trying to track down the bad ground with common sense and methodical troubleshooting has, in every instance in my experience, taken longer and yielded worse results than simply shotgunning the problem, attacking every ground that can be found.

My advice is to start with the bigger grounds that you can see under the hood. The big ones between the engine block alternator, and the chassis. The grounds near the fuse box, and on the firewall. The battery terminal. For each ground, remove the lug, wire brush the lug and the contact point, put it back together. While you're at it, inspect for cancer in the ground wire/strap itself. Is it all green or white powdery? Replace it.
All good now? If not, dig deeper. Attack the smaller grounds and grounds in harder to reach places. Inside the doors, inside the dash, under the center console, behind the glove box.
Keep digging deeper until by process of elimination you stumble upon the offending ground. After that you can take out the multimeter, take measurements, and as an academic exercise theorize why the bad ground in the passenger tail light was causing the radio to come on full blast every time you turn left. But trying to do it the other way around (trace problem with a DMM from the radio to its source) never works.

I started in the engine bay and cleaned a few grounds then tested them I got 0.0 Ohms on three of them and 0.1ohms on the patch cable I installed for the additional ground of the wiper circuit which didn't make any difference to the wiper trouble.
That's the only grounds that I could find on the left side engine bay.

Is that after adding the ground that you mentioned?

No, I did the toggle switch month or so ago. Yesterday I added a ground by tapping in to it's ground and then going to - of the battery. A month ago I grounded the wiper's motor by way of it's casing and it made no difference just like yesterday's ground. Thanks

 

@John La Out of curiosity and to help better understand the schematic I looked up the wiper motor and boy is that one of the dumbest contraptions ever built. The factory troubleshooting equally sucks and doesn't seem to include any useful testing other than checking if there is power or ground with the harnesses disconnected... unfortunately that won't find a weak connection that is good enough to make the meter show right, but not make the motor work right. It sill sounds like a ground problem from your description.

It almost looks like the motor is grounded through a wire while the control side is grounded through the case in the schematic. Do you still have the case ground as well as your added spliced in wire?

Edit...
it looks like you are getting some help in your wiper thread. Hope everything works out in the end.

 

@John La Out of curiosity and to help better understand the schematic I looked up the wiper motor and boy is that one of the dumbest contraptions ever built. The factory troubleshooting equally sucks and doesn't seem to include any useful testing other than checking if there is power or ground with the harnesses disconnected... unfortunately that won't find a weak connection that is good enough to make the meter show right, but not make the motor work right. It sill sounds like a ground problem from your description.

It almost looks like the motor is grounded through a wire while the control side is grounded through the case in the schematic. Do you still have the case ground as well as your added spliced in wire?

Edit...
it looks like you are getting some help in your wiper thread. Hope everything works out in the end.

No, I don't have the case grounded nor was it made that way. I did a short test to see if they would park with the additional ground. Yesterday, I tapped in to the ground of the wiper circuit and went straight to the battery but there was no change with the issue. Here is a picture of the ground. Thanks