Car alarm- doors not arming?

Thread Starter

John La

Joined Oct 8, 2022
57
I have a simple Black Widow one way 2800 series car alarm that has worked for over 20 years and now the two doors are not arming. The alarm no longer resets it's self I must reset it with the key fob. Once I reset it everything seems fine such as the led flashes, the shock sensors chirp when they should and when I open the trunk the alarm goes off as it should. This is a two door car and neither of the doors when opened will activate the alarm? Also my windshield wipers will not park and will not turn off unless I pull the fuse. I replaced the wiper motor and have tried two different dash switches plus the original and none have made a difference as the wipers still will not turn off and go to the parked position. This all seemed to have happen when I pulled the stereo from the dash as the equalizer stopped working. Could this be a ground issue? What should I test. I do have DVM and some experience testing continuity, voltage etc. I enclosed pictures of the circuits. Thanks
What I've found so far is that when the module and the wires going directly into it are moved around ever so slightly the door triggers will arm as they should. Example- I set the alarm then open the door, the alarm should have went off but didn't so I then move the module around ever so slightly then the alarm goes off. That's were I left off. I will spend time on this latter today.
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.
 

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eetech00

Joined Jun 8, 2013
3,418
My suggestion would be to first check the voltages at the +/- Door Trigger input terminals (depending on which ones used).
The +Door Trigger should have 12v when any or all doors are opened.
The -Door Trigger should have Ground when any or all doors are opened.

Also, What voltage do they have when any or all doors are closed?
 

twohats

Joined Oct 28, 2015
362
Are you in the USA?
In the UK wiper motors use earth/ ground to park the wipers when switched off. (Don't know about newer vehicles).
eetech00 is offering good advice.
Can you bypass the door/s switch and test at the input, directly at the module?
Please keep us posted.
Good luck.............
 

Dodgydave

Joined Jun 22, 2012
10,591
That is a Ground issue, the doors pull to ground and self parking on wipers use ground to latch in stop, i would retest ground to the chassis.
 

Thread Starter

John La

Joined Oct 8, 2022
57
My suggestion would be to first check the voltages at the +/- Door Trigger input terminals (depending on which ones used).
The +Door Trigger should have 12v when any or all doors are opened.
The -Door Trigger should have Ground when any or all doors are opened.

Also, What voltage do they have when any or all doors are closed?
My interior lights come on as they should when the door/doors are open. I wanted to ad that fact. How do I check the - door trigger, should I do a continuity test on that one? I will test these in a day or two. I do appreciate your help very much. Thanks
My suggestion would be to first check the voltages at the +/- Door Trigger input terminals (depending on which ones used).
The +Door Trigger should have 12v when any or all doors are opened.
The -Door Trigger should have Ground when any or all doors are opened.

Also, What voltage do they have when any or all doors are closed?
 

Thread Starter

John La

Joined Oct 8, 2022
57
Are you in the USA?
In the UK wiper motors use earth/ ground to park the wipers when switched off. (Don't know about newer vehicles).
eetech00 is offering good advice.
Can you bypass the door/s switch and test at the input, directly at the module?
Please keep us posted.
Good luck.............
Yes, I can get to the module and test as needed. My vehicle is a 1993 Pontiac Grand Prix GTP. Thanks
That is a Ground issue, the doors pull to ground and self parking on wipers use ground to latch in stop, i would retest ground to the chassis.
To test ground to chassis I assume I would do a continuity test from - on the battery to the ground on the chassis? Also, should I look for the individual ground point of the module? Such as follow the ground coming from the modules ground terminal to it's ground point? Sounds like you think these are related issues. I will retest ground. My vehicle is a 1993 Pontiac Grand Prix GTP. Thanks
 

Thread Starter

John La

Joined Oct 8, 2022
57
Are you in the USA?
In the UK wiper motors use earth/ ground to park the wipers when switched off. (Don't know about newer vehicles).
eetech00 is offering good advice.
Can you bypass the door/s switch and test at the input, directly at the module?
Please keep us posted.
Good luck.............
Yes, I'm in the USA. Thanks
 

eetech00

Joined Jun 8, 2013
3,418
My interior lights come on as they should when the door/doors are open. I wanted to ad that fact. How do I check the - door trigger, should I do a continuity test on that one? I will test these in a day or two. I do appreciate your help very much. Thanks
Use a voltmeter so we can measure the voltage and be sure to test at the alarm terminals.
To test the + input trigger, ground the meter -lead and touch the +lead to the +trigger input terminal.
The meter should read close to 12v ( about +/- 2v)
To test the - input trigger, connect the meter +lead to +12v and touch the -lead to the -trigger input terminal.
The meter should read close to 0v (or ground)
 

Thread Starter

John La

Joined Oct 8, 2022
57
Use a voltmeter so we can measure the voltage and be sure to test at the alarm terminals.
To test the + input trigger, ground the meter -lead and touch the +lead to the +trigger input terminal.
The meter should read close to 12v ( about +/- 2v)
To test the - input trigger, connect the meter +lead to +12v and touch the -lead to the -trigger input terminal.
The meter should read close to 0v (or ground)
When testing the - input trigger, you want me to connect the + lead to +12v. I'm not sure about this step. Do you want me to connect the + lead to 12v ? such as off of the car battery? Please explain further
 

eetech00

Joined Jun 8, 2013
3,418
When testing the - input trigger, you want me to connect the + lead to +12v. I'm not sure about this step. Do you want me to connect the + lead to 12v ? such as off of the car battery? Please explain further
Yes. Just find a convenient +12v connection point. You can use the +12 power connection terminal on the Alarm unit. Just make sure +12v is live at the Alarm +12 power terminal. You have a meter....you can measure this.
 

strantor

Joined Oct 3, 2010
6,338
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.
 
Is the radio still out of the car? If so it may be possible the antenna wire is serving as a ground and would explain why things started acting up after your removed it.

One of the problems with automotive stuff is there is no guarantee what you ground to the body in the passenger compartment is going to transfer through the different body panels and finally to the battery. In the beginning there is paint separating the panels where they are bolted together, and over time it turns to rust. Most of the time there is enough bare metal contact somewhere to make the circuit, but it's not guaranteed.

As strantor said just start checking everything. Normally there is a connection between the battery and fender, battery and engine, engine and firewall, and possibly engine and fender opposite the battery. If in fact the antenna was acting as a ground it would point to a bad connection between the firewall and engine / battery / fender (depending on how it was built)
 

Thread Starter

John La

Joined Oct 8, 2022
57
Yes. Just find a convenient +12v connection point. You can use the +12 power connection terminal on the Alarm unit. Just make sure +12v is live at the Alarm +12 power terminal. You have a meter....you can measure this.
Does it matter if the alarm is in activation mode? I am testing it today and appreciate all help. Thanks
 

Thread Starter

John La

Joined Oct 8, 2022
57
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.
Thank You.
 

Thread Starter

John La

Joined Oct 8, 2022
57
Is the radio still out of the car? If so it may be possible the antenna wire is serving as a ground and would explain why things started acting up after your removed it.

One of the problems with automotive stuff is there is no guarantee what you ground to the body in the passenger compartment is going to transfer through the different body panels and finally to the battery. In the beginning there is paint separating the panels where they are bolted together, and over time it turns to rust. Most of the time there is enough bare metal contact somewhere to make the circuit, but it's not guaranteed.

As strantor said just start checking everything. Normally there is a connection between the battery and fender, battery and engine, engine and firewall, and possibly engine and fender opposite the battery. If in fact the antenna was acting as a ground it would point to a bad connection between the firewall and engine / battery / fender (depending on how it was built)
I have these factory manuals (2 book set) that were used at the dealership. I am reading these and trying to understand where this S211 junction point is. Thanks
 

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I am reading these and trying to understand where this S211 junction point is. Thanks
I would guess it's probably close to the main connector in the firewall under the dash. It's just going to be a bunch of smaller wires connected to a bigger wire with some heat shrink tube on it. Good luck... it will be buried in the harness somewhere.

Edit...

Find out what all C211 has connected to it. I was assuming the main firewall connector, but it is possible it is a sub assembly connected to the main harness. It may be easier to start there and work your way out.
 
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Thread Starter

John La

Joined Oct 8, 2022
57
I would guess it's probably close to the main connector in the firewall under the dash. It's just going to be a bunch of smaller wires connected to a bigger wire with some heat shrink tube on it. Good luck... it will be buried in the harness somewhere.

Edit...

Find out what all C211 has connected to it. I was assuming the main firewall connector, but it is possible it is a sub assembly connected to the main harness. It may be easier to start there and work your way out.
The pictures shows the wiper switch, radio ,cigar lighter etc. is connected to C211 ground. For all I know the EQ could have failed due to ground issue. I am going to connect the EQ to a battery and see if it works. It did cut off once in a great while. Thanks
 

eetech00

Joined Jun 8, 2013
3,418
Does it matter if the alarm is in activation mode? I am testing it today and appreciate all help. Thanks
Here is a diagram of a 2800 I found on the internet.
Hopefully, its the one you are using.
If so, you can use the wires "RED" = +12v, and "BLACK" = Ground for testing. but don't disconnect them from the unit.
The voltage measured across the RED and BLACK wires should be a constant 12v (it should always be 12v, even if the ignition switch is off).

Do you know which type of door trigger you are using?
Does the door trigger change from nothing to +12v when the door is opened? or closed?

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Thread Starter

John La

Joined Oct 8, 2022
57
The door triggers are the factory installed pieces such as a push pin type. That is the same diagram I'm using and have a print out of. I had some things I had to take care of today and couldn't do anything but tomorrow I will have all day to test. I will have the answer to these questions tomorrow. Thanks
 
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