Need help diagnosing a bad starting/electrical issue.

[B-Ryan]

Try to follow me here, because it's rather complicated and has a few scenarios.

So I've got my 2001 MP3 which is having trouble starting. I'm going to point out right off the bat that I've got a failing alternator and I have a replacement just waiting to be installed by a friend (can't afford a shop). I don't know if it's related, but there is a problem with the sensor in the driver door that makes the car think the door's always open unless I slam it hard a few times.

That being said, here's my issue:

For no reason whatsoever, and usually unpredictably, when I turn the key to ACC, everything on the dash lights up ok. As soon as I turn it to the ignition position, everything dies. I completely lose power, to the point that my radio even loses all its settings. Takes anywhere from 30sec to a min to even regain my odometer, at which point there's no juice to do anything.
So when this happens, I connect my handy jumper-pack to the battery (which I now keep in my back seat at all times) and one of 3 things happens:

1) Same thing happens again.
2) The car starts normally.
3) The lights on the dash stay on even when I turn the ignition to start. When this happens, through trial-and-error I learned that I needed to set my alarm off (factory alarm) and then hit unlock on the remote to get my ability to start back.

These 3 things have no particular pattern of happening, it's completely random. For instance today, I drove to the gas station with no issue. After filling, I had to jump it (scenario 3). Drove home, turned the car off. Waited 5 mins and test-started without a problem. Went outside to go out 6 hours later and I can't get it started (scenario 1).

A few ideas have been floating around when I asked people about it:
-Bad starter.
-Ground problem with door sensor that's draining the battery.
-Alarm system is defective and the ignition-kill is grounding out.
-My car hates me.

I'm reaching out in desperation to see if any of you have had similar experiences or could offer some insight. I'm a computer guy, not a car guy.

Thanks in advance!

-Brian

 

[04spoondc5]

i am having damn near the exact same thing happening. i am spending time investigating my issue today i will let you know if i come up with anything.

 

[04spoondc5]

check neutral safety switch on clutch, switch should have no resistance until clutch pedal is depressed. check for 12volts to the ignition switch. i pinned out the computer and opened it up, no burnmarks, pcm checks out good. i think the alarm system has burnt up in my vehicle, more than likely same case for you, you can either bypass or replace it. let me know if you find any for sale.

 

[DarthNewky]

check neutral safety switch on clutch, switch should have no resistance until clutch pedal is depressed. check for 12volts to the ignition switch. i pinned out the computer and opened it up, no burnmarks, pcm checks out good. i think the alarm system has burnt up in my vehicle, more than likely same case for you, you can either bypass or replace it. let me know if you find any for sale.

Guess I should be happy mine didn't come with an alarm. Don't remember the numbers but some had them some didn't.

 

[04spoondc5]

i bypassed the alarm and now it cranks, just unplug the jumper harness to your steering column for the alarm and itll crank right up

 

[B-Ryan]

i bypassed the alarm and now it cranks, just unplug the jumper harness to your steering column for the alarm and itll crank right up

Which harness are you referring to? I know it's tight, but is it possible to send me a picture?

When looking under my dash, I see the central alarm unit with 3 plugs in it (2-pin, 4-pin, and one that's bigger.)
Then there's a plate mounted up-top with 3 connectors attached to it.
1 is black and says "B150 DC12v ... 1B06", 1 is yellow and says "Relay - Door Lock", and 1 is white saying "Flasher ... Turn Signal ... Hazard Warning".
I've tried different combinations of unplugging the connectors, but nothing will get the car started. On the bright-side, the dash isn't dying when I turn to ACC.

While I was under the dash, I tried toggling the alarm on/off with the remote. Only when I pressed unlock did I hear a buzzing coming from under the dash, which you could hear in the engine compartment. Noticed the "door open" light also dimmed (Only when unlocking), and I couldn't open more than the driver's door. Found the buzzing noise coming from the Flasher/Turn/Hazard box (verified by actually holding it and feeling it vibrate). Opened it and saw no scorch-marks but I'm wondering if this could be one of the answers? When I plug in everything else but this box, I get power to the dash straight to the ACC position on the ignition. I hear a single cligk from the right side of the dash, but that's it.
When I plug this module in, the dash goes back to dying.

 

[04spoondc5]

unplug everything connected to that mazda alarm box, yank out the shock sensor and the little safety switch lead under there