OK, I have spent a year and a half of pretty steady work converting an S5 NA to a JDM Turbo. This was a chassis up rebuild. I am ALL done except for it won't start and stay running. I have tested and replaced several components (AFM, OMP, Thermal intake temperature sensor, pressure sensor, and ecu. Now it comes time to pull the codes, and my check engine light won't come on at all. I pulled the bulb, all ok, checked for continuity back to the ecu for that circuit, all ok. Could this be a cold solder problem, or another bad CPU?

 

CPU won't control the CEL.

Does the light come on if the key is in the ON position but the engine is not running?

 

The CEL will not come on at all. When I turn the key to the on position without the car running, it does not come on at all. I should be more specific it is not the cpu, but it is the engine computer that it connects to. I was wondering if it is the cold solder joints in the idiot cluster.

 

How about going to pin 1E and seeing how the output compares to the values given in the FSM?

And are you sure the light bulb is any good in the CEL light location.

 

I checked the Pin 1 E last night and with the key turned to the on position, the voltage started at around 4.5 volts and slowly dropped over a period of 3 to 5 seconds close to zero. On the bulb, I took one out of another socket that was working and placed in the CEL socket...no light. The test connecter was grounded. I tested the pin 1E with the plug in the ecu. THe way I read it, it is supposed to be less than 4.8 volts and then go up after 3 seconds to 12v. Mine is slowly dropping to zero.

 

Disclaimer: I don't own a series five.

Seems to be a ECU problem at first sight. Or a short in the wire going to the CEL. Maybe pull the plug off the warning light cluster and ohming that wire out to ground with the plug off the ECU?

Is this a USA ECU? Part Number??????????? N3???

I mildly wonder is all the light bulbs are the same in that warning light cluster???? A little bit of a wild guess.

What resuts do you get if no bulb is in the socket??? Constant 12v???? Or???

 

I'm assuming you are swapping a S5 JDM? If so they don't have a CEL. I wasn't able to get mine working either and was told they don't even have one, you need to pull codes like on a S4....
Here's my thread: https://www.rx7club.com/showthread.p...k+engine+light

 

I am using an N370 American ECU and harness. I did use the JDM motor, but this should not effect the CEL.

 

Hmm, if you're using the N370 it should work then, which engine harness are you using?

 

Using an S5 NA converted to Turbo. Not a whole lot of difference. I had the entire harness out and apart (unsheathed) to check all of the wires for wear and defective wires. I need to test the wire to the CEL to ground as the voltage is dropping at the pin 1E from 4.9 volts to zero when I turn the ignition on. It is supposed to go to 12 volts, not to zero.

Have any other ideas? I am wondering if it is grounding in the idiot light cluster?