car wont start. ecu dead?

kicknaoffroad · Post by **kicknaoffroad** » Sun Jun 13, 2010 10:01 pm

hey guys, wasnt sure if i should post this in the engine section or the emissions. i dont even remember the emissions section the last time i was on here so i just posted in here. anyway, i went to start my car for work last thursday morning after it had sat for 3 days since i was driving my si and nothing happened. no starter click, no cranking over, nothing. the interior lights came on and dash lights. that was it. being in a hurry, i just drove my si to work and waited till i got home to mess with it. my first thought was a dead battery even tho that didnt make too much sense since it would have to be completely dead for no lights. so i tryed to jump start it. when that didnt work i checked all the relays/fuses and they were all good so i took off the lead to the starter and jumped the starter. the starter cranked over the motor fine and the car would not start with the key in the on position while i did that. one thing i noticed is that i didnt hear the fuel pump kick on. i figured it was a bad ignition switch which wasnt allowing the starter to crank or the fuel pump to to work. i finally got around to changing the ignition switch out tonight and i still have the problem. when i do the keyfob trick to pull up codes it doesnt do anything and my check engine light takes about 15 seconds to come on after i turn the ignition on which if i recall correctly it should flash on for a second as you turn the key on. my car has ran fine other than having to replace the cam position sensor a month ago for the 3rd time. i usally drive the car 3 to 4 times a week. i'm starting to think my ecu might be bad. any ideas guys?

v95 · Post by **v95** » Wed Jun 16, 2010 2:00 pm

well i've been going thru the same problem on my friends 300zx and i first went to fuel pump relay cause that died then stater relay and now i now battery but when I did the screw driver trick with the starter it turned over. I think my friend just f'd up the ignition when he jerry rigged his alarm in the car.

But for you Id say just replace fuses and dome light to be sure. if you know the screwdriver trick try that and if car turns over its the ignition and if it does not its the starter.

OB · Post by OB » Wed Jun 16, 2010 3:45 pm

You didn't hear the fuel pump so you replaced the ignition switch? I would have simply checked for power at the pump before throwing parts at it. If the pump doesn't cycle every time you have the key on, there's a problem. First make sure the fuel pump is good (apply 12V manually to it if necessary). Did you check the ASD relay and main fuel pump relay? What about the ignition relay to the starter?

Post by **occasional demons** » Wed Jun 16, 2010 4:44 pm

Stated he checked the relays/fuses, but not sure on how this was done.
Note:
Profile says hasn't been on here since the day he posted.

It seems like The ASD relay, and starter relay are not energizing, or are both bad. Just the ASD will not keep it from cranking. I would check for voltage at the PDC, and the PCM mounting and ground points for corrosion. If the PCM is not grounded, there will be nothing happening.

04sxt2.0 · Post by **04sxt2.0** » Wed Jun 16, 2010 5:26 pm

check one one of the over 40 amp fuses, i had an issue like this, found a blown fuse, replaced and everything was good. dont remember which one it was but it was one of the over 4
0 amp pink fuses.

kicknaoffroad · Post by **kicknaoffroad** » Tue Jun 22, 2010 8:51 pm

OB wrote:You didn't hear the fuel pump so you replaced the ignition switch? I would have simply checked for power at the pump before throwing parts at it. If the pump doesn't cycle every time you have the key on, there's a problem. First make sure the fuel pump is good (apply 12V manually to it if necessary). Did you check the ASD relay and main fuel pump relay? What about the ignition relay to the starter?

thank you for the reply, but wow... read much before you post? i wasnt simply throwing parts at it. thank you occasional demons for reading my post and replying. yes i did check the asd relay and the main fuel pump relay, as well as all of my fuses. after that i checked the pcm mounting/grounding points, its connections as well as the connections at the fuse block. the reason i replaced my ignition switch was because after checking all these things it made sense. the fuel pump as well as the starter did not do anything which is a common symptom of a bad ignition switch. not to mention its alot cheaper than buying a new ecu. you can unplug the fuel pump relay and crank the car over all day. this has nothing to do with the starter. and after replacing my ignition switch that is what led me to believe it was my pcm. i did come on here and check for replies however i did not log on so it did not update my profile. i did in the end order a new pcm and then towed my car up to the dealership yesterday when it came in. they flashed the new pcm and the car fired right up. thanks again to those of you who made helpful replies without an attitude.

Haganracing · Post by **Haganracing** » Wed Jun 23, 2010 1:27 am

Glad to hear your neon is running again! Sucks you had to buy a new pcm

kicknaoffroad · Post by **kicknaoffroad** » Wed Jun 23, 2010 9:37 am

thanks! yeah i'm glad it is running again too! ecm wasnt the cheapest fix but at least i have my daily driver back and can enjoy 38mpg again. not to mention, that now i can take my civic to the track again with my new 8.5lb flywheel/new clutch, without worry of not having a car to drive if i break something

Haganracing · Post by **Haganracing** » Wed Jun 23, 2010 3:58 pm

Haha yeah man. Its always good to have a good running DD

Normally if my neon is broke.. my truck (my back up driver) will soon break right after.. Its an attention whore