LA02MAX

iTrader: (3)

Hey guys,

My friend's '03 6 speed turns over but doesn't start. It's been sitting in my driveway for quite some time because it had a flywheel vibration issue. It ran whenever it was parked there and some time within the past 2 months, it decided to quit starting. We've since replaced the flywheel and battery and it still doesn't start. The current verdict is that the car isn't getting a spark signal, so I'm wondering what all the requirements for this are.

Here's what we've checked:

All fuses
Swapped CPS with my car
Swapped ECU relay with my car
Checked ignition pins on ECU harness
Checked to see if security light was on while starting (it isn't)

I'm not great with electronics but I followed some of the diagnositc procedures from the FSM regarding ignition signal and I'm not seeing anything on my multimeter...I'm unsure if i just can't reach in far enough to touch the metal lead on the harness or the signal just isn't getting transmitted to the ECU. I'm getting a reading when testing the battery, so i know the multimeter isn't broken - but it says on most of them that i should be seeing battery voltage when testing a certain pin and ground and i'm not seeing anything. (ie: Pg. EC-690 in the FSM)

Can someone give me a detailed how to on how to test the harness output against ground? Also, what are all the "start requirements" for the ignition signal to be generated. As far as i know, it's pretty much just the immobilizer, right?

Thanks in advance for the help.

SurraTT

iTrader: (59)

Start with what engine codes you are getting, hook up a OBD2 scanner to the car, there are too many possibilities of whats wrong at this point.

LA02MAX

iTrader: (3)

well like i said the car is in my driveway...i don't have access to one. I'm just wondering how to test the pins on an ECU harness using a multimeter.

SurraTT

iTrader: (59)

yeah, you can get a obd2 reader for dirt cheap now days. Anyone doing work on a car should have one.

Start with the codes to find out whats going on, no need to mess with testing ping on ecu harness when you don't know which ones you should test.

It could be there is a signal the ecu is not getting so its not allowing the motor to crank up.


I can tell you the ecu needs cam sensor signals to fire the coils, otherwise the coils will not fire at all. And the early cam sensor's had issues.

LA02MAX

iTrader: (3)

Just trying to avoid throwing additional money at it... I know an OBD-II scanner is beneficial but up until now it hasn't been an issue just taking it to auto-zone when I needed a code pulled.

That signal is the one I'm trying to check. An example from the FSM is as follows:



The ports on the harness that the ECU pins are inserted into are very small. I'm getting a 0V reading in the above condition but it's very hard for me to tell if the multimeter lead is touching the metal in the harness or not. Is there a trick I'm missing?

I'll check the cam sensors when I get home.

nismology

iTrader: (8)

Is the tach jumping around when you crank it?

LA02MAX

iTrader: (3)

No it isn't. I'm gonna go buy a pack of needles to try and see if that'll connect to the harness better to see if I'm getting that igintion signal then I'll start looking at other things. It's just weird that it just quit running out of the blue.

nismology

iTrader: (8)

I would swap over your CPS and the associated subharness. If the tach isn't getting a signal, the ECU probably isn't either.



Edit: I see you already tried the CPS. That's what I get for not reading lol. Have you tried the subharness though?

LA02MAX

iTrader: (3)

Haven't tried the subharness. I'm either gonna look at it this evening or tomorrow...been busy this week getting my yard prepped for a storm, etc.

I'll take a closer look at the tach next time but I don't remember seeing the needle move at all. Has an OEM flywheel so the ring gear shouldn't be the problem and like i said, the flywheel has changed since it started having this issue - I would enjoy it very much if it were the sub-harness, though, so i'll check it out. Also gonna swap cam sensors with my car and double check the ignition signal with a needle this time.

LA02MAX

iTrader: (3)

Just an update (since the threads i searched never had a solution) - I swapped cam sensors and the crank sensor harness. I am getting a little bit of motion on the tach, so i know that's getting a reading but still no start. I tested the ignition signal on the ecu harness and still zero. Guessing maybe the ignition switch or immobilizer. Having it towed to nissan next week (depending on the hurricane...) so they can diagnose it...$85 flat rate and that's applied to any repair done. not too shabby.

LA02MAX

iTrader: (3)

It ended up being the immobilizer... the receiver portion of it in the ignition cylinder had to be replaced, hence the reason i was getting no ignition signal to the ECU.

nismology

iTrader: (8)

Heh, yea my old 5.5 (now my brother's) has had the NATS unit go bad twice in the 3 years it's been in the family. Glad you finally got it pinned down.