No ECU power... No start

[mo_hish]

1993 240sx s13 (97 ka24de w/ s13 distributor)

Drove the car this morning to the store, parked it... 5 min later came out and the car wouldn't start. Popped the hood, and found the fuse box cover off, and the ignition coil ground was off. Put the cover and ground back on and wouldn't start.

What I know:
CEL won't come on
No spark
Fuel pump wont prime
Relays and fuses are good
ECU only getting 1.4v at power pins (pins 47 & 38.)
When I jumper 3&5 at the EGI relay, the CEL comes on and the ECU gets power (full 12v at power pins) but wont start
When EGI is jumpered, fuel pump will prime when I unplug the distributor
No spark with or w/o EGI relay jumpered
Pin 36 (Ignition) gets 12v with key in on position
Pin 34 (Start signal) gets 10v while cranking
SAFC still turns on
Opened the ECU and everything looks/smells fine


I'm lost. I'm assuming it's a wiring problem and I'm considering getting another harness, but I don't want to get one if it's not even going to help...

[mo_hish]

Anyone? I'm running out of ideas.

[mo_hish]

Ok, so I backprobed some stuff and found a few questionables.
I backprobed the EGI relay, and all 3 wires are getting 12v (with the key on) except for the black/white (power to the ECU?) wire. I'm guessing thats why when we jump the 3 & 5 pins, the ECU gets power. I'm actually pretty sure I get spark with them jumped... It's kind of hard to see, but its there.
Also, I backprobed the ECU checking continuity with ground to see if there was a bare wire touching the chassis or something like that. All the ECU and various sensor grounds that go into the ECU are fine. The ones I'm not sure about are:
Pin 113 (SB) - AAC Solenoid
Pin 45 (G/Y) - Ambient Switch > G > B > FICD
Pin 24 (R) - Check Engine Light (MIL)
Pin 36 (B/R) - Ignition Switch
I had my multimeter set to beep if it was a continuous circuit (1 lead on ground, and checking the pins with the other lead)... with these, it didnt beep, but would sound like static, then if I turned the key to the 'on' position, it would immediately go away. I checked the voltage with the key 'on' and all seemed fine.

[teamsprock]

I am going to bump this back up and see what others have as suggestions. I believe I am having the same if not similar problem. My car ran fine, then nothing. Checked and found that the 25amp fusiable link for the EGI was blown. Replaced the fuse and still no power to the ecu. So I checked everything just like you with my multi meter. Apparently my Ecu ground (pin #4 on a #62 ecu) is not working... If I ground the wire everything works fine. I assume pin #4 is now bad and no longer is working as a ground.

Can anyone comment if it would be a bad idea to bypass pin #4 and run a switched ground? That way I would turn my ECU on with a switch and avoid having to buy a new ecu.

[mo_hish]

According to my pinout, pin 4 (r/b wire) is the ecu relay. Try doing what I did and jumper 3 & 5 at the egi relay and see if that works.. I've read that a few people just run there cars like that bypassing the relay. If that doesn't work, check the continuity of that wire from the relay to the ecu

[teamsprock]

According to my pinout, pin 4 (r/b wire) is the ecu relay. Try doing what I did and jumper 3 & 5 at the egi relay and see if that works.. I've read that a few people just run there cars like that bypassing the relay. If that doesn't work, check the continuity of that wire from the relay to the ecu

Yes jumping the relay gives power to my ecu and things work fine. pin 4 is the ground trigger wire for the relay and on my car that is what is not working. Bypassing the relay cause my ecu to always be on, and that is why I am considering just running a switched ground, so I can turn it on and off.

[vqdreaming]

sounds like this is what's happening to me, you mentioned something about your ignition switch not getting continuity im almost lead to believe that would be the problem although im no expert.

[vqdreaming]

does your fuel pump turn on when you turned the key on?

[mo_hish]

My problem was the ecu.. I swapped it out last week and it worked fine.

I say you go with the switch if it works.. Hide the switch and it'll be an extra layer of security

[vqdreaming]

so im guessing the ignition switch in the ecu was bad? or do you know exactly what was wrong with it?

[rayrayh22a/s13]

i have this same problem, i finished the s13 swap started the engine it started and died a couple times(i figured it was a vacuum or maf this as long as it started) then it wount start at all no spark no fuel, so i looked around the igniter chip was broken (i dont know how that happened), the FL25A(ret mtr) and FL25A(eng cont) fuse blew so i change them and i got a new igniter....tryed stating engine again it started and was still dieing like before but now it wont start, and the red led bulb in the #62 ecu wont come on now until i loop 3 and 5 in the egi relay terminal then it comes on but still no spark no fuel........................i swap out the s13 ecu and put back the old 240 ecu, led light comes on the # 3 pin in the egi relay now has power on its own with out the relay in there

[poo40vert]

im having the same problem right now.
my ecu leds wont come on. no power to fuel pump.
the car will crank but ovbiously no turn over via lack of fuel.
i tried 4 different ecus.
Im about to swap out the engine harness to see if it makes a difference.

anyone have any other tips?

[Pure_JDM]

I'll bump this thread, as when i have my old ECU plugged in, it will flash, but when I plug my new SR20 ECU in, it does nothing. Everything comes on, but the car will not even turn over.

[240sx-pat]

PURE JDM did you ever resolve the issue

[jrs1]

Ok, well im halving about the same problems. When turning the key to the on position i have some powere, but when trying to get it to start, it does nothing. It also makes no noises. I charged the battery and nothing, i had jumper cables and another car to jump my s13 with you a ka24e and nothing.

If anyone has a answer please help

[stelth213]

ay did swaping the harness fix ur ecu not turning on problem?

[jrs1]

Swapping the harness??

[stelth213]

Ok, well im halving about the same problems. When turning the key to the on position i have some powere, but when trying to get it to start, it does nothing. It also makes no noises. I charged the battery and nothing, i had jumper cables and another car to jump my s13 with you a ka24e and nothing.

If anyone has a answer please help

have u tried checking ur starter?? remove it n take it to an autozone if im correct they might check it for free!

[jrs1]

They will chech it for free, its just that when i turn the key on i also relized that the fuel pump dont turn on either, and i have no power to the inside of my car either, well besides the light from opening the door.

[ka4life87]

This is going to sound stupid but are your battery cables clean? I once had an ecu problem with my s13, not as bad as yours but i had problem. I have my electric fans wired to the condensor fan relay and all of a sudden they werent turning on anymore. Also the engine stumbled at times when idling and ecu wasnt grounding the relays, i got a complete ecu pinout online and checked every wire for 12 volts and ground and after like 3 hours of diagnosing, i decided to clean my battery terminals and fans kicked on! Weirdest thing, sometimes the simplest fixes solve the most complicated issues.

[isaac]

Hi guys i put an s13 sr20det engine in my s15 non turbo used a s15 turbo loom started and ran sweet then removed plenum and put aftermarket one now do not have any power to the ecu pins anyone have any suggestions????
cheers