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Hello everyone, my 2009 G37s coupe (6 speed MT) will not start.
About a month ago the car would occasionally require several presses of the push to start button before it would turn over, and I didn't think much of it. On the failed attempts it would just cycle through ACC back to off. Then one day recently it took about 20 presses and I was lucky to get it home.
The battery tested fine but I tried a new replacement just in case, which did not fix it. I tested the clutch pedal sensor and it seemed questionable so I replaced it, but that did nothing. I took the starter out and it passed multiple bench tests at autozone. I replaced it anyway because it was the original part, and I'd rather not go through that pain in the *** job again in 6 months. Still no crank. I checked the starter relay and it works. I checked continuity to the starter and it's good. The steering wheel lock functions as it should. All fuses are good as far as I can tell. There are no codes being thrown.
I've read a hundred threads and I'm about to throw in the towel. To summarize the current state of the car: with the clutch pedal depressed, pushing the start button once unlocks the steering and I can hear the starter relay click. Pushing it a second time lights up the dash and headlights. Pushing it a third time turns everything off. I open the door and the steering locks again. No amount of pressing will get it to attempt a crank. I don't remember if this is normal, but the red car-shaped light with a key in it flashes continously during this process.
The only new interesting thing I've noticed is that the words around my push to start button (lock, acc, on) no longer light up in sequence when I cycle through. The white button itself still lights up though.
You mentioned the clutch pedal switch "seemed questionable," did you also check the cruise control and brake switches as well? Additionally, there are rubber stoppers that go on the actuator end of the switches- make sure they are still attached and secure. Though the brake/ cruise control might not play a direct role in the engine start sequence on 6MT cars, it never hurts to check all the same.
Any evidence of water in/near/around the BCM (passenger side footwell area)? All connections tight, dry, etc.?
How are you checking the starter relay? That is integrated into the IPDM/er and is not user-serviceable. Do not confuse the steering lock "click" with the other relays...
Are ALL connections at the battery clean and secure? There is a lot going on at the positive terminal: connections, fuses, etc. Are they clean and tight?
The red key icon flashing could be a issue. When the car is completely OFF that icon should blink once every second. Anything more could be a issue with IVIS (immobilizer). Is the icon flashing any different than what I mentioned?
Have you tried starting the car with the key fob inserted into the slot?
I did check the cruise switch, but not the brake switch, so I'll do that. The clutch switch was giving me intermittent resistance in the 100 Ohm range with the button pressed, hence the questionable nature. Once I got a new one and tested it, it was a clean short by comparison. I really thought that would solve the problem at the time.
I have never checked the BCM but I will shortly.
The starter relay is removable from the IPDM and I checked it with a 9V battery. It gives a nice solid click every time. I also didn't want to confuse the various sounds so I had someone else press the start button while I listened next to the IPDM and it definitely clicks.
I am honestly only semi-confident about the positive terminal assembly now that you mention it. I read good connections between the various bolts and the battery, but the thing has seen better days for sure. I think I will order a replacement to rule that out.
The red icon does flash every second or two but it doesn't stop flashing when I try to start the car. I can lock/unlock with the fob and enter ACC mode. And my car seemingly goes through all the motions to start other than actually turn over. From what I've seen, the immobilizer will cause the start button to do nothing like if I get in without my fob, right? With that said, I have been wondering if maybe the weird lack of lighting around my start button could be related to the immobilizer.
I replaced the battery in my fob and I've tried slotting it in while starting. It seems to be perfectly functional and recognized by the car.
Thank you for the ideas, I'm going to double check the switches and look into the BCM now.
If IVIS had been tripped, the red car/key icon would remain solid and the car would not do anything. Virtually, dead.
If you are getting 12V at the clutch switch (clutch not pressed down) then that circuit should be good. The clutch switch opens the circuit when you press the clutch down.
It sounds as if you are on the right track. Keep in mind there are two (2) starter relays: the starter relayAND the starter control relay:
When the BCM closes the starter relay, 12V+ is sent to the control relay. When the IPDM/er closes the control relay, 12V+ is sent to the starter which should crank the engine. You checked one relay, I'm not sure if the other can checked as well.
Last edited by ILM-NC G37S; May 7, 2022 at 03:08 PM.
Well I went ahead and replaced my battery terminal connectors but it didn't change anything.
I got the BCM out and it looks immaculate. No signs of water or corrosion anywhere down there. I reattached all the connectors and started doing some troubleshooting via the BCS section of the service manual. I didn't realize there were two starter relays, so I looked into that first, following the diagnostic that I attached here.
In Step 1.2, I should be reading battery voltage with the clutch depressed but instead I read ~0.1 volts...not good. Proceeding to 2.3, I measured good continuity between the IPDM and BCM. In 2.4 I got no continuity between IPDM and ground. Since 2.3 and 2.4 are both "correct" results, it tells me to replace my IPDM.
I don't quite understand the logic but I guess replacing the IPDM is the next thing to try?
Sadly, I think that is the issue. I believe you checked the external "Starter Relay" whereas the integrated "Starter Control Relay" can not be checked/ replaced by the end user.
The way I understand it, once the BCM has gone through the process and verified a good key (judged OK to start) it closes the "Starter Relay" coil which sends 12V+ (switched) to both the IPDM/er CPU and the "Starter Control Relay." Once the IPDM/er receives this signal, and judges OK to start, it then activates the "Control Relay" coil. Once the control relay is closed, this completes the circuit which sends 12V+ to/ and physically engages the starter. The IPDM/er has sole control over the starter through the control relay. Once the engine starts (or in event of a crank/ no start condition), the control relay is opened disengaging the starter.
I am sure this dual relay method is intended as a security function.
At this point, I would remove the IPDM/er and give it a good inspection. Make sure everything is clean and dry and see what happens. I am sure you checked all the fuses/ links at the positive cable, but a second look over would not hurt.
The good news is that there are plenty of IPDM/er's on eBay for reasonable prices- just be sure to match your year, model, and powertrain. There is no programming necessary- it is a direct plug-and-play replacement.
Perhaps others will have other ideas on what to check/ diagnose.
Did you end up finding a resolution. Im having what sounds like the exact same problem.
James, I was just wondering if you ever figured yours out. I wish the original guy would respond. I'm currently fighting the same issue. I'm 80% certain my IPDM is bad, but idk. Pretty complicated system to test. Totally overengineered. My car kept cranking slower until one day it quit cranking. I tried a new battery. I pulled the starter and had it bench tested. It passes, but still sounds dry to me. Today I'm searching for someone that can load test the starter. So frustrated. 😞
[QUOTE=jetson;4310628]Hello everyone, my 2009 G37s coupe (6 speed MT) will not start.
About a month ago the car would occasionally require several presses of the push to start button before it would turn over, and I didn't think much of it. On the failed attempts it would just cycle through ACC back to off. Then one day recently it took about 20 presses and I was lucky to get it home.
The battery tested fine but I tried a new replacement just in case, which did not fix it. I tested the clutch pedal sensor and it seemed questionable so I replaced it, but that did nothing. I took the starter out and it passed multiple bench tests at autozone. I replaced it anyway because it was the original part, and I'd rather not go through that pain in the *** job again in 6 months. Still no crank. I checked the starter relay and it works. I checked continuity to the starter and it's good. The steering wheel lock functions as it should. All fuses are good as far as I can tell. There are no codes being thrown.
I've read a hundred threads and I'm about to throw in the towel. To summarize the current state of the car: with the clutch pedal depressed, pushing the start button once unlocks the steering and I can hear the starter relay click. Pushing it a second time lights up the dash and headlights. Pushing it a third time turns everything off. I open the door and the steering locks again. No amount of pressing will get it to attempt a crank. I don't remember if this is normal, but the red car-shaped light with a key in it flashes continously during this process.
The only new interesting thing I've noticed is that the words around my push to start button (lock, acc, on) no longer light up in sequence when I cycle through. The white button itself still lights up though.
Thank you for any help or ideas.
Hello I had the same issue that your having I took done exactly what it is your doing so here is what fixed the issue for me on your positive battery cable there is a fuze block built into the positive battery terminal that needs to be replaced it's not very expensive you can order it offline and it's guaranteed to fix your issue hope this helps
