1993 240sx ecu

[300ZX90NA]

ok well after so many weeks of following every single wire and checking relays and fuses i checked the ecu and where the black and pink wire goes into the computer its burnt so i got a hold of another computer and as soon as i turned the key it burnt it again could this be cause by a short if so does anybody happen to knw where this short could be coming from?

[300ZX90NA]

ok forgot to put this down ive replace it three times and i jus noticed rite now on the third one that as soon as i turned the key since it was dark i saw it flash i opened it up and saw that the circuit coming from pin 104 the black and pink wire its blown i checked the original computer and its blown from there as well and i had bought one from a junk yard and thought that it was jus bad so i opened it and the same thing i so now if anybody can give me an idea where to start the search for the short before i buy another computer i would really appreciate it thank you

[r3v_v3ng3]

its a short. stop replacing it the part cause itll blow up again. check your grounds. download the fsm and figure out whats that wire for and trace it

[300ZX90NA]

thxs i didnt knw that the ecu kept blowing up or i wouldnt of replace it till i figured this out but thanxs now have to figure out where the short is coming from

[sx moneypit]

According to Alldata, circuit 104 is the fuel pump relay drive.

[300ZX90NA]

sorry it was dark when i was going through these wire the wire is black and red pin #36

[elwesso]

What have you done to the car recently? Most common times I see ECUs blow in this fashion is when people redo the MAF sensor connectors and switch wires, or in this case it could be if you installed, say a walbro fuel pump

[300ZX90NA]

i havent done much to the car i bought it not working the distributor was bad got a new and replaced it and checked all the wires and relays the main relay wasnt turning on so i checked the ecu opened it up and saw the circuit where pin # 36 is connected to is fried i checked the the old and new ecu and there both fried from the same place so now im trying to figure out where the short is coming from does does anybody know how much voltage is supposed to be going out of the ignition coil on the black and red wire that goes into the ecu?

[sx moneypit]

With the key on it is battery voltage.

[sx moneypit]

Pin 36 is on the same circuit that powers the pulse air control solenoid, the ignition coil and the ballast resistor.

[300ZX90NA]

thxs for the help well after a month of working on this car and getting frustrated i finally heard it fire up for the first time it was a great feeling now all i have to do is time it and put everything bak together and drive it like theres no tomorrow=]

[sx moneypit]

No problem brother! What did you find?

[vancouverbc]

No problem brother! What did you find?

plus 1.

[300ZX90NA]

well my joy was short lived i finally thought i found the short coming from the black and red wire going into the ecu it worked well for 3 days and when i was backing out of my driveway the car died no spark checked the ecu and it go burnt from the same spotif anybody can tell me if a bad coil can cause this to happen or give me an idea please and thank you

[sx moneypit]

You need to check all the components on that circuit. I have to say i have not seen a coil short like that but it is possible. I am kind of leaning towards the pulse air solenoid.

[rioredstang]

Pin 36 is ignition sense circuit. It should see 12v when switch is in the on position. I did not see any thing else on the diagram on this circuit. Have you checked the condenser by the coil? If its bad could this be spiking computer? Have you added any thing on your car like a cooling fan or something?

[vancouverbc]

the resistor/condensor as well. it is circled in pic. completly melted in this pic. i think it unplugs, never heard of the 24osx coil going bad.

[300ZX90NA]

no i bought the car not running so haven't really started working on it like i did on my z i got a mechanic to come take a look at it and he "supposedly fixed it" didnt even get it out of the driveway when the car died checked the ecu and it fried it again so he never fixed the short so now i knw never to use that mechanic again does anybody knw a good mechanic in the riverside area?

[300ZX90NA]

i tested the coil and the coil is passing 1.1ohms and its supposed to be passing .7ohms could that be the problem of my short?

[vancouverbc]

i tested the coil and the coil is passing 1.1ohms and its supposed to be passing .7ohms could that be the problem of my short?

i thought it was 1 and 10 ohms? what resistance do you read when you touch the multimeter probes together? test your resistor/condensor for ohms.s/b arouund 2300 ohms

[rioredstang]

If you cut the wire going to pin 36 it will stop frying the computer. It should set a code 21, but it will still run. You can then drive it to get get help. The condenser acts as a buffer to smooth out voltage spikes from driver transister to the ecu.