So, long story short, my N370 ECU bit the dust. I was able to get my hands on an N374 locally, and it works great so far. However, I noticed the CEL never comes on, and upon reading, it never will. So what do people do in Japan for a CEL? And is the CEL really necessary on this car? I suppose it would be nice to be able to pull codes on it...

 

Forgot to mention, the car has a wideband O2, which will help with knowing if something is wrong, but it really sucks that I can't pull engine codes. Is there still a port/connector somewhere on the vehicle that I can put a scan tool on?

 

Nope.

 

Well damn. Are engine codes really that important?

 

I don't think so, I removed my CEL bulb a while back and I have an N370. The car is simple enough to diagnose without the computer.

 

My only was silly crap. Like bad sensors and what not. But, my wideband O2 should mostly cover that

 

Exactly, the ECU is not smart enough to be of any use as far as I can see. I suppose if you were aiming for the best gas mileage it may be of some use. I personally don't care if my TPS or my IAT is bad because theres no way in hell I'm going to replace them. Theres no narrow band O2 so that doesn't matter. It won't be able to detect a bad injector, or plugs, fuel pump, etc.

The main sensors on the car almost never go bad (AFM, MAP). If the OMP goes bad the car will be in limp mode and you'll feel it. I'm pretty sure theres still a way to retrieve codes with that ECU though, I think you have to connect a test light to one of the diag plugs on the shock tower and retrieve the codes. I know there's a thread that explains how to do it as I remember coming across it in a search.

 

if you look in the FSM there is a way to get the codes with a pair of lights or voltmeters, this will work on the N370 and N374....

or if you had the code reader that would work too

the JDM ecu has no light, but it does have the same diagnostic connector as the US spec

 

Where is the diagnostic connector located?

 

big green plug by the driverside headlight

 

You guys rock, thanks!

 

Obviously you've only owned 1 rx-7, and it has been the most trouble free one possible. i've got a pile of bad ECUs MAPs AFMs and TPS', only a couple of bad injectors/IATs.




Looks like the spread of misinformation PLAGUE is back.

 

^^ Could you explain? So will using lights/voltmeters not work to pull codes?

 

In the area of your LEAD coil assy there is a GREEN six scoket elect plug called a Check Connector and it's used for downloading fault codes.

It has three wires. One wire is black/white and if you use a couple of common LED's from Radio Shack, that black/white wire will power the LED's.

The other two wires in that connector are from the ECU and pulse a ground to the LED's when the ECU sees a fault.

So you buy two LEDs from Radio Shack. They have two wires each. One wire will be red and you will splice both red wires of the two LED's together and put a spade connector on the end. Then insert that single spade into the socket of the green check connector where the black/white wire is.

Now you have two wires left from the two LEDs. Put a spade connector on each of those two wires. Insert those two spades into the sockets of the green check connector where the other wires in the green connector are.

Then you ground the single wire that is the Initial Set Coupler. That is a green single wire connector near the LEAD coil assy.

Now with key to ON if a fault exists, the two LEDs will blink a code.

I've never done this on a series five car so I'm assuming it will work.

Someone else can explain the codes and which LED goes where in the green check connector. I'm tired right now and wanna do something else with my time.

Read this and see if it helps explain things a bit more: http://fc3spro.com/TECH/HOWTO/ERRORC...KI/kerror.html

EDIT: I meant to post this instead. It's how to make a LED check light assy for series four cars. You'd make yours the same way. http://www.teamfc3s.org/info/article...odes/main.html

 

I appreciate it Hailers!

 

Remember, I said I'd never done this to a series five myself, but the last link shows how to make a checker out of two LED's from radio shack. Cost is very, very small.

So if it works, then look at the series five list of codes and not the series four list of codes. I assume the LED's will blink if you short the Initial Set Coupler and have the key to ON, engine OFF.

Let us know if the LED'S do blink a code on your N374

 

I'll check it out this weekend.

 

Not sure if anyone is still wondering, But IT IS POSSIBLE to pull codes using the two-light method with a N374.
I've done it on my S5 TII running that ecu. Its the best $3 I've ever spent on the car. Use that writeup from Hailers, Thats what I used.