Hello all!

New to the group/forums altogether, so if I'm not in the right area - sorry!

I just got my first 2003 G35 sedan 6-speed rear wheel drive this year. Traded a crappy 1992 Mercedes 400SE for it, and I've been stuck ever since... :/ I did get it non-running, so there was my first mistake.

I love Nissan, but this thing has been a nightmare from day 1. I solely attribute that to the previous owner, as he did all kinds of dumb things to this poor car. (cross-threaded flywheel bolts into the crank - that was a fun fix, destroyed most of the body work, and hacked up the wire harness...).

I still have a no-start condition, and I'm so saddened by this, as I've never encountered something so seemingly impossible to fix! The vehicle is bone stock. I haven't done a thing to it

Issue: No spark. Coils do get power, but no signal to fire.

What I've done: Replaced spark plugs, crank sensor, cam sensors, checked and Ohmed out every wire and sensor to check for continuity, properly indexed the flywheel, checked the ECU (it's fine), checked the cluster (it's fine), and checked all my connections to ensure everything is making proper contact. Checked compression, and it's good. So, mechanically, it's sound. I've for sure got an electrical gremlin somewhere.

I haven't checked the BCM, and my radio/climate controls aren't even present. The BCM is my next suspect though. When I turn the key to the "ON" position (right before you crank it over), I don't see the NATS light or check engine light. They don't pop up temporarily and go away. They just don't show up at all - which is really suspect to me. That's telling me there's a communication issue somewhere, or would I be wrong to assume this?

I'm getting fuel for sure, as it stinks after I crank for a little (while I was doing initial testing).

I've been at this for about 7 months now... I'm just about over this whole car, but I really don't want to give up. I feel this car is worth saving, but I'm at my wits end with it. Ugh... Halp??

 

Welcome! Out of curiosity, have you tried taking it to a dealership / electrical specialist? Maybe you could pick up a parts car and just swap all the electrical stuff over, keep what you want, and part out the rest to recoup costs.

 

Here's how the system works, put your key in and turn to the ON position, the BCM reads the transponder on the key and if it's a matching programmed key the anti-theft system PASSES. Turn the key to START, as long as anti-theft has PASSED and there is a visible continuous signal from the CRANK SENSOR (CKP) then the system will engage the starter relay and the fuel pump relay. Fuel primes pressure while cranking, during crank the ECU reads the data being sent by the CKP and the CAM SENSORS (CMP) to determine when exactly to open the fuel injectors and when exactly to deliver spark.

A failed CKP will prevent starter engagement, faulty data will deliver spark and fuel at the wrong time and/or send a DIAGNOSTIC TROUBLE CODE (DTC).

A failed CPM will either deliver spark and fuel at the wrong time and/or send a DTC.

A failed fuel pump will NOT deliver fuel and in most cases will NOT send a DTC, this can be tested with a sandwich adapter for the passenger fuel damper that allows you to hook up a fuel pressure gauge.

Spark can be tested by removing one spark plug, reattach it to the coil pack and hold the ground strap (curved part at the end of the plug) about 1/4" away from the intake manifold while someone else cranks the motor, spark should be visible, always wear a dry leather glove or you will probably be zapped.

Once you have verified you actually have FUEL and SPARK then it's time for a trip to Nissan for a diagnostic.

 

Unfortunately, I can't afford a trip to the dealership as of now. That's why I was mainly hoping to self-diagnose this one. I'm not new to cars in general, but new to anything post-1998. haha

If I could find another $300 sedan, I'd swap everything over. Well, electronically anyway. Engine is ~170 psi across all 6, so I'd be keeping that for sure. I'm just kind of stuck now.

 

Correct. I did a checklist of system functions, and it all checks out minus the ECU. I can communicate with it via scantool, but I don't know if it's sending signal to the coils to fire. I am getting signal from the crank sensor though. So, potentially cooked ECU? Didn't look bad from a visual inspection. Nothing corroded, burnt, or un-soldered. (sigh)
Though, would that be consistent with my CEL and NATS lights not illuminating temporarily upon turning they key to "ON"?

 

It's a common practice at shady dealerships to physically break the CEL so it doesn't turn on. When you turn the key to ON the cluster does a lamp check and your service engine soon light should turn on. If it doesn't then it's probably been intentionally broken, that's not a signal from the ECU the self-check is initiated by the cluster. The NATS indicator LED (above the left air duct outlet) test can be initiated by arming the system, that's not part of the ECU anyways though, that's a BCM function.

 

Yeah, I've tried two different clusters, and both yield the same result.

My latest suspicion, is that somehow the BCM might be my culprit all along. Someone told me that it basically works as a relay point for communication between the cluster and the ECU. I don't know how factual this is, but if they communicate through the BCM and it's cooked - I could see why there may be issues.

 

The instrument cluster reads data from the CAN system so it gets data from multiple sources, vehicle speed comes from the VDC control unit, tach and water temp come from the ECU, fuel gauge is a resistance value directly from the fuel pump, IPDM sends information for oil pressure, RAS and TCM sends CAN data for those indicator lights, etc.

I'm almost positive though that the only CAN data being sent from the BCM is the door switch closed signal, I can't verify exactly where the source is for the systems check of the service engine light however it almost ALWAYS originates from the ECU.

You can also test operation by unplugging the Mass Airflow Sensor while the engine is running, it will not damage the engine, it will turn the service engine light on, and the code should self-erase when you plug the MAF back in.

 

Well, the only thing is... it doesn't run. haha Can't get it to run either.

Been dead in the water for over 7 months.

The odd part about this, is that I don't even get a temporary check engine light or anti-theft light when I turn the key to "On." Hmm...

 

Have you tried pulling the codes with a code reader? If the idiot light is broken and it has codes you should still be able to read them, maybe they might just point to your issue.

 

Ok I just re-read your first post and caught something, "my radio and climate controls are not even present" does this mean you don't have the AC auto amp controller installed (part that has the clock on it)? A lot of instrumentation stuff actually goes THROUGH the AC auto amp and if you don't have one installed that can definitely be a problem.

Think of the instrument cluster being two parts, the first half is the combination meter above the steering wheel, the other half is the AC Unified Meter Control Amp.

 

I did, and I kept getting a crank sensor code... Crank sensor is new and good (Ohmed it out), wiring is good, and flywheel is properly indexed. I even treid another cluster, and same results. No CEL light or Anti-Theft light upon turning the ignition to on. Super weird.

 

The clock is present (the one with the anti-theft status light on it). So, that's there. However, the head unit and climate controls are currently out. Busted beyond repair thanks to the PO. Ugh...

 

So the car thinks something's wrong with the crank sensor. When you're cranking the engine do the RPMs move? If they don't that's another sign of the crank sensor being bad. Checking the ohms doesn't necessarily mean the part is good, I had a bad coil pack which passed the multimeter test with flying colors but still caused the car to misfire like crazy.

If it's an aftermarket sensor many of those are known to be faulty out of the box sometimes and not work for very long even when they work initially. The OEM ones (which work) are $100 a piece on Amazon, but you might be able to return the new sensor you bought and get another one which might work (just tell them the code didn't go away and they should warranty it).

 

Yeah, I was worried about that. I know it's a hall effect sensor, and they're hard to diagnose without an exciter wheel on a test bench. Stupid things are fragile as china glass too. Ugh...

Yes, I'm getting RPM readout. So, that's the confusing part. Maybe it's kaput, but puts out just enough for instrumentation readout, but not actual functionality.

I'll be so mad, but so happy if it is that sensor... lol