Need help identifying random circuit board question

[delicanter]

Hi all,

I'm trying to figure out what this circuit board is. It's dangling under the steering wheel / radio area. One side has three wires that are actually connected to something while the other side with two wires isn't connected to anything.

I know that the previous owner of this vehicle had it broken into and the ignition switch was replaced, perhaps this is part of an old alarm/immobilizer system?

Thanks!

 

[mickdub]

according to datasheet the chip is a timer.

DigChip IC database

"
DESCRIPTION
The M51843P monolithic timing circuit is highly stable controller capable of producing accurate time delays, or oscillation.
Additional terminals are provided for two voltage comparators. triggering or resetting, it desired, applicable for a wide range of usage as monostabie or astable multivibrators. The circuit consists of noise filter pin, shutdown control circuit, and zener diode for supply voltage regulation. providing excellent anti-noise characteristics."

so it suppose to 'time' something
it could be alarm
is there anything written on the other side?

 

[delicanter]

Thanks.

I looked up the IC as well but couldn't figure out what purpose its actually serving. There's nothing printed on the back side.

There is no alarm but perhaps this is part of an old alarm/immobilizer?
There's a backup camera but the wires going into this circuit seem original wires originating from the Delica electrical system rather than an aftermarket backup camera.

 

[mickdub]

i cannot say for sure.
this chip is timer, and used in alarm systems, aircons, lights, flash light (like police or ambulance), and has a thousands of other uses. everywhere you need timing delay these chips are used. it designed and manufactured by mitsubishi, but i don't remember having this board in my l300 (1996). mine has all mechanical brain
it could be something like alarm or immobilizer.
for example, these 2 missing wires could be connected to siren
it is really difficult to say anything based on pictures

or it could be one of these 'fake' alarms, when you have a LED blinking in the vehicle
it looks like these 2 missing marked as LED

try to check output with multimeter, if if come like on-off-on and again, it might be a 'blinker'

 

[mickdub]

it has to be some number on the other side, like serial number

 

[delicanter]

Thanks, great idea to test the output with a multimeter.
I'll also try to trace the wires going into it.

There's nothing on the back unfortunately

 

[mickdub]

to bad. from picture i can say there is +12V in, some switch wire, and most likely ground (-12V)
i would check with multimeter with ignition off voltage on +12 and wire in the middle first. i would expect it to be alive
then i would test output for signal

 

[delicanter]

Thanks, will do and will report

 

[Growlerbearnz]

It looks like you've got + and - power in, a SW(itch) input, and an LED output.
Where do the LED wires go to? It could be an overly-complicated flashing LED/fake alarm.

 

[mickdub]

It looks like you've got + and - power in, a SW(itch) input, and an LED output.
Where do the LED wires go to? It could be an overly-complicated flashing LED/fake alarm.

thats what i think

 

[delicanter]

It looks like you've got + and - power in, a SW(itch) input, and an LED output.
Where do the LED wires go to? It could be an overly-complicated flashing LED/fake alarm.

The two wires marked LED go nowhere, they are just cut out after a few inches.
Someone tried to steal this car from the previous owner, maybe this is the remainder of the collateral damage.

 

[delicanter]

Btw if its some sort of real/fake alarm how would you imagine its turned on/off?

 

[mickdub]

Btw if its some sort of real/fake alarm how would you imagine its turned on/off?

cut the wires, isolate ends or trace where it come from and disconnect at source

 

[Growlerbearnz]

The SW input would probably go to the ignition switch (or some circuit that is on when the ignition is on). I expect it would flash the LED all the time, unless the SW input is on.

It does seem excessively complicated for that though.

 

[Growlerbearnz]

cut the wires, isolate ends or trace where it come from and disconnect at source

There, I fixed it. ;-) If @delicanter doesn't trace those wires we'll never know what it is!

 

[mickdub]

last night i was connecting parking security cameras with radar
basically, it looks very similar by idea
one wire goes to the ignition group, yet another goes to the battery group, device which works like relay, when ignition is off, power comes from battery, once ignition on, battery power cut off and power comes from the ignition group.
this one looks utilising same idea, so +12 and -12 with ignition off should report 12V to multimeter, with ignition on it should be +12 and Switch.
but i am sure with ignition off two LED wires will pulse voltage to multimeter. just a guess
@delicanter, check you fuse box, it might be connected over there. say, left top 3-4 fuses and left bottom
3-4 fuses.

 

[delicanter]

Cool I will investigate later today and let you know what I find, thanks.

 

[mickdub]

Did you find out what it was?

 

[delicanter]

couldn’t get to it yesterday but will surely today

 

[delicanter]

Ok, here goes:

I tried to trace the 3 wires coming into this circuit but it’s impossible without taking apart the dashboard. The wires snake up along the steering column into what looks like the dashboard.

I tested voltages with a multimeter and at no point did I get 12V. Not when the car is off, switch on, car running. No matter what combination of the 3 incoming wires. However I did get a 1V reading on several combinations, namely the SW and +12V wires. I got zero voltage on the two output wires.

I’m tempted to simply cut off the 3 wires, cap them and call it a day.