Just wanted to what the CPU #2 is used for? I have an issue with it and know that it controls the seatbelt light and beeping and the alarm light. What else does it control? Could it's malfunction be a reason my battery kept draining?

I currently have the harness disconected until I replace it, but is there any potential harm to driving this way?

Thanks

 

Nevermind, more attemps at searching led me to this:

"The CPU #2 also contains logic for the Turn Signals/Emergency Flashers, Headlight Dimmer, DRL's, Seatbelt & Key Alarms, Key Cylinder Illumination, BRAKE warning light, tells the AT ECU if the HOLD Switch is On Or Off, and other things."

Anyone have a used one for a MT for sale?

 

Yeah, CPU #2 controls a bundle of stuff. Its alarm system has been known to go a little crazy but I'm not sure how it could cause a current leak itself. If it is misbehaving, the fault should be obvious from the device/lamp it is controlling.

 

is cpu#2 necessary for the 13b to operate properly?

 

The engine will work, but turn signals, pop up lights, the brake warning light, the high rpm warning, and a whole host of other minor things will not.

 

I've had a current leak for a while, not a problem if I run the car more frequently but when it sits a bit longer than it should it would need to be jumped. Also during this time the ignition key illumination light would sometimes stay on, my passenger headlight stopped popping up, prior to the light not popping up the lights changed how they moved when the alarm was activated, used to alternate the lights and then they both moved in unison. Now I also noticed the seat belt light flashing constantly and turn signals flash faster than it should when I use it to indicate a right turn, left is fine.

I think the current leak was noticed after the passenger headlight stopped working. So I guess it makes sense now and this thing was probably on it's way out for a while, with more issues related to it's malfunction occuring as time has gone on.

 

thanks moconnor, i'm puting a 13b into a non rx7 so i suppose that stuff wont matter for me. if i can ask you on more question:
the harness i have seems to plug into half of my ecu, is the other half where cpu #2 would go?

 

No - CPU #2 in in the driver footwell.

 

cpu 2 does not control pop ups or any of that non sense. cpu 2 is for alarm functions. When the alarm goes of the lights flash and go up and down and all that junk. it is the black box above the flasher unit and starter cut relay on the driver side foot panel. it is not need for the car to run or any major functions on it.

 

Please do a little more research before you post. The so-called 'flasher unit' is CPU #2. CPU #2 is not 'above' it.

Here is a picture:



CPU #2 incorporate a lot of functions in addition to alarm and flasher functionality - as already discussed in this thread.

 

Ok sounds like i dont REALLY have to have it since my shell car will have those functions through it's computer. My question is this:
i have what seems to be a complete engine harness and it fills up the left 50% of the ECU's slots what is the right 50% for? is that where the body harness of the FD would plug in? Thanks for answering my complete NOOB questions.

 

update to this thread. I was having a problem with my seat belt light not going off. it would always just keep blinking. I unplugged just the middle plug from cpu #2. My seat belt light no longer flashes, but it doesn't beep either. The head lights still pop up, the power door locks still work, the turn signals still work, the horn still works, pretty much everything still works except for the seat belt alarm. The stock alarm might not work any more, but i'm not sure.


So yes, you are able to unplug just the middle plug and retain almost all functions.

(taking out the bottom plug disables the blinkers and what not.)

 

the seatbelt light in my car would not stop blinking, so i unplugged the middle connector on CPU2. this fixed the blinking and beeping... thank god. but, if doing this does disable the stock alarm, will it pose any issues when i install a better security system?

also, if you unplug the middle connector, the car no longer beeps when the key is in and the door is open. it also does not beep when the headlights are left on

 

This doesn't work on a JDM version 2. The windows no longer work with this unplugged.

 

Bumping this thread. Lately i notice my security light dont flash anymore when i lock the door and shut , before or after . But the alarm goes off if triggered. And my seatbelt light dose not flash if i drive without my seatbelt. ( Bottom is connected )
And i believe my high rpm beep dose not work. But lowcoolant light dose beep if light is on

 

kensin,

To be sure, check the light bulb for the SECURITY light during the power-on test. Maybe it blew out? Do you hear the alarm beep when the door is locked? Remember, the alarm would arm after the key is removed from the ignition, driver locks driver door using the inside door lock AND door open, all other doors closed (hood/bonnet, hatch, etc).

Your seat belt light is functioning normally. I suspect you are accustomed to the constant seat belt warning logic found on newer vehicles. In the FD, the seat belt light and buzzer only sounds during the first few seconds after engine start or the key is placed into the ON position. The light and buzzer will go out after 30sec (approx). At that time, Mazda believed that a driver would be responsible enough to buckle up once the car is on. When we see/hear that constant warning in modern cars, the car manufacturer is effectively nagging you to put on your seat belt.

It is possible to have the security function on the Body CPU to crap out while other functions remain untouched. That circuit is on the main CPU board behind the long surf board panel of the assembly. However, double check the light bulb is making full contact with its socket and it isn't blown out. Without other info, I'd say that your Body CPU is ok. Do you have any other unusual electrical issues with the car - turn signals, flashers, headlights not moving up/down properly, or even battery drain? Another common symptom of Body CPU failure (for the alarm) is the double beep when arming the security alarm and the SECURITY light would have an erratic flash rate.

Cheers,
George

 

Gen2n3, thanks for the heads up. Guess i never notice it . I didnt take notice untill i rode in a friends fd the other day

i notice he didnt have his belt on 5 minute into the drive and the seatbelt light was flashing. After i told him to to buckle up thats when the light stopped thats how i thought mine was faulty

and as for the security light. Before, when i lock the car before shutting the door. I would hear a beep. And then after shutting the door. About 5 seconds later. Another beep and then the security light on the tran cover would flash once per every 5~10seconds ? Maybe slower. And another red dot somehwere on the dash would flash too. Cant remember where. .. indicating security system is on. But after many moons. My tran cover light stopped. But the beep is still there aswell as the dash light flashing.
everything else is working nothing seems out of place

 

Kensin,

No worries, any time! I don't know what to say about your friend's unusual seat belt light. Back to your car, alarm seems to function normally minus the SECURITY light on the center console. Again, that appears to be a blown light bulb. Did someone wire in an additional red LED on the dash? Do you have an aftermarket alarm installed on the car too?

Cheers,
George

 

I know I'm really late to the show, but did fixing or replacing the CPU 21 work?