my car is at the shop and they said my cpu was bad, because my car will not crank and i get no power from the battery to the car. and i been looking all over the place and i cant find where its located or what it looks like. also what is the cost of one.
any input will help

 

The CPU is located in the right side of the passenger footwell under the black plastic. Remove the plastic clips to expose the CPU.

I would call Ray at Malloy Mazda to see about a replacement although he probably only has new ones and they'll be pricey. I'm sure guys have the stock ones for sale here on the forum.

You could probably also contact Pettit Racing (www.pettitracing.com) to get an upgraded one from them that will allow you to run more boost. Make lemonaide out of lemons I say!

 

Are you talking about the ECU or CPU? You just installed a new Power FC right?

There is a CPU on the driver's side footwell. I actually have a picture of it from your old FD when I was checking it out. It's the black box that says FD01.

 

cpu not ecu. i have a power fc

 

thanks man. thats what i needed.

 

how sure about these guys are you????? seen way more starter interupt realys and clutch switches go bad than cpu's.... not saying it never happens just....

 

Extremely remote it is the Central Processing Units ( CPU ) which is located A) #1 behind the fuse box inside the car, drivers side footrest area B) #2 behind the panel by the driver side footrest panel.

Those are not the problem, bet a happy meal


Later

 

/agreed with badddrx7


what shop?

 

This is what you need to look at.

 

You need to take your car out of that shop,as you can see above the cpu has nothing to do with the starter

 

CPU #2 contains the stock alarm circuitry (in addition to a bunch of other things) so does interact with the starting system. You can see that it feeds in to the starter cut relay in the above electrical diagram.

Mine failed due to a botched aftermarket alarm install and, while not common, other have reported failures here too so I would not rule it out. The Body Electrical manual (in the stickies) has a diagnostic procedure for checking it out. It is very much prone to giving odd alarm behaviour if the battery is low too.

 

well its at the rx7store. and thats just what they told me. im thinking it can be a main relay but im not sure, im not real good on electrical things.

 

i know its something but i dont know what. first the boost controller/gauge went out then the car kept blowing the green 40 fuse. then last my radio stopped playing and then of course the car will not start. if i hook a jump box to it. it will crank but sounds like im getting no power through the car. i know its a short somewhere or a bad ground but im just going by what was told to me by the rx7 store. and they said it the cpu.

 

If the RX7Store says it's CPU #2 then it probably is. You can pick one up in the classifieds for $70 or so. PM Fritz on this board - he usually has a few.

 

Doh! Sorry guys, thought you were referring to the ECU. Now back to the thread...

 

Yes the theft deterrent system is controlled by CPU No2 and can prevent starter motor operation by interrupting the starter cut relay.

It is hard to understand how applying a jump box to the battery allows the starter motor to operate if the starter cut relay is being interrupted---it does not compute.

 

no i have a battery relocation kit so its in the bin. when i hook the termanals to the battery i get no power. but if i hook the jump box to the positive cable under the hood and the negative to the shock tower. i get some power but for some reason it seems like not enough. the power fc reads 12-13 volts but it wont crank.

 

yep you got me confused---the above tells me the engine cranks.

 

it will crank if the jump box is hooked up under the hood. if hooked to the actual battery nothing happens. thats what im saying

 

What do you mean by 'hooked up under the hood'? You mean directly to the starter? If so, you need to go through the diagnostic procedure in the Body Electrical manual to identify the source of the failure.

 

If the engine cranks with the jump box positive connected to the positive cable coming fom the battery(in the engine compartment) and negative to the car body or frame and using the ignition key to make the starter turn,then starter circuit,including the starter cut relay must work.

Then your problemwould appear to be the battery or cables from the battery--positive or ground.

 

thats exactly right. but the battery is new and it could be the cables. but what i dont understand is that the day before the car started right up then i went back the next day and nothing.

 

well bad connections can work that way----one day good ,next not.

 

ill tell him to check it

 

Troubleshooting a problem is all about clues....you are sorta like a CSI. You look at what is different, what has changed, what has moved, witnesses and sometimes the hand of God strikes down in a divine way and makes things just happen. Well you are supposed to gather all this data and plot a course of action. Well I am going to plot you out a course of action, follow this and report back. Get out your green shop manual ( now everybody who dare owns a third gen and wants to perform repairs has a shop manual). Go to page G-4 in the engine electrical troubleshooting section. Begin with " Will not crank-starter motor does not operate". Step one - Is the battery fully charge ? Step two - Is 12volts present at the Starter main battery cable ?. Step three....well you get the picture.

Perform this task ( investigation, because you are a FD CSI now) and report back. Together we will find root cause.


Later