i have a 89 turbo2 with a jdm s4 block and s5 intake and exhaust parts. my mil light does not come on when i turn key on. if i ground the yellow/blue wire off the ecu the light works. if i ground the green check connector on drivers front in engine bay by coil pack, the light doesnt come on. it seems that its not getting a ground somewhere. i cant find any better diagrams in the online fsm.

 

Mil?

 

Malfunction indicator light

.....I had to look it up

 

sorry, just another term for check engine light.

 

MIL? is this a GM???


Anyway if any of the warning/idiot lights (including the Check Engine light) does not turn on when you turn the key to the ON position, but do not start the car, the either the idiot light bulb is burnt out or the idiot light panel is bad.

 

ok, all other lights on panel work. only the enginelight is out. i did a bulb check and it works. i need some better wiring diagrams on that circuit, like what grounds it to cause it to come on. i wish i had a spare ecu to try or a spare idiot light unit. i'll try and look at it somemore.

 

I guess you didn't understand my last post in this thread if you are saying you need a spare ECU to check it

 

I thought your millling machine broke for a second there.

 

Mazda call it a malfunction indicator light too. Don’t you read the FSM?

It’s clearly shown in the FSM wiring diagrams. All the warning lights share the same power supply and they’re switched on by various items providing switched grounds. The MIL is switched by the ECU, so if the bulb’s okay and all the wiring checks out (do a continuity test), then it might be the ECU. This would be very unusual though.

 

Are you running a JDM ECU? I'm having the same problem with a JDM engine where the check engine light traces to the ECU fine but doesn't come on and I've heard the JDM FDs don't have a check engine light so maybe it's the same for FCs.

 

Correct, Japanese FC's have no CEL/MIL.

You can make a code reader exactly the same as the S4 one, but with only one LED instead of two. At the diagnostic plug connect the LED's positive wire to the pin with the black/white wire and connect the LED's negative wire to the pin with the yellow/black wire. Then follow the S5 procedure for checking codes with the CEL.

S4 error code reader: http://www.teamfc3s.org/info/article...odes/main.html
S5 error code reader: http://www.johnr.com/cpucodes.html

 

well i think i have a n374 ecu. i am not getting 5 volts signal output of ecu to the sensors. so thats why i cant get it to idle. i also have a bad tps and possibly a bad maf.

 

Yea, the N374 is the JDM ECU which I also have. I opened up the ECU and traced the pin that controls the CEL and it looks like there is an unpopulated capacitor and resistor that branches off the output transistor to ground that drives the "FAIL" Pin 1F for the 6-pin check connector for pulling codes.

I bet if that resistor (circuit part #900) and capacitor (circuit part #C901) are soldered in, the JDM ECU would drive the CEL properly.

Can anyone with a US N370 ECU open it up and see what kind of resistor and capacitor are in those circuit spots?