If you remove the battery, you can clean the terminals with your favorite brand of carbonated soft drink. Rinse with water and place back into the car.

 

Just make sure you don't do this in garage or get on paint it is corrosive since soda will not neutralize the acid build up. If you get on floor rinse off after with water same for paint. It's easier to use brass wire brush and vacuum

 

I'm having same/similar issue to the original poster, 2008 G35S sedan 6MT

I have already done the following, short of just starting to replace fuses I'm curious if there are any ideas for me to try.

Replaced battery - checking at 12.57V with the car off (obviously) and drops to 11.52 when pushing start button
Replaced starter - was getting just one click (still am) and just went ahead and pulled starter, got it tested, it failed, put in a re-man, no luck, pulled it, tested good, and still no luck
---I've double checked a tight connection on the starter and secondary clip connector seems to plug in well
Checked main fuses at positive terminal (cleaned terminal very good, as well as negative), connections are tight
Checked fuses next to battery all look OK, don't have the shift lock relay due to 6MT
Checked fuses in driver footwell all look OK

I hear the steering column unlock when pressing start button, key seems to be recognized (unlocks doors, lights come on, etc.), horn beeps when locking, only hearing a single click from starter area still, can hear some type of valve actuating under hood after pressing start button.

I tried junketing the clutch switch with a paper clip and no change, might not have gotten a good connection though

I'm kinda at a loss as to what to try next, and its a long tow to the dealership.

Any ideas?

Thanks

 

From what it sounds like there is a issue with either the "B" and/or the "S" terminal connections at the starter itself.

You should read less than 0.5V drop in voltage between the battery and the "B" terminal at the starter per the FSM. You indicated 12.57V at the battery and 11.52V at the starter. This is just under 1V which is out of spec. How much voltage is being lost when the starter tried to engage?

The "S" terminal (small plastic connector) should read battery voltage when the start button is pressed. Need to check that reading.

If you are getting any clicking noises at the starter more than likely the starter is not getting enough voltage to turn the engine. Being that you are getting the clicking noise leads me to believe the fuses and relays are okay.

 

Checked voltage at the starter and while it’s been sitting battery is measuring 12.45 across its terminals and I’m getting 12.44 at the b terminal of the starter, so not much lost there. This is just with the car sitting there, not trying to push the start button

will check s terminal voltage in a little while when I have a helper to push the start button.

will try to jump/charge the battery with my truck and see if that helps

 

If you are brave (and have proper gauge wire), you could run a jumper wire from the "S" terminal on the starter and try tapping the (+) terminal at the battery to see if the engine cranks. If you try this do it WITH THE KEY OFF/NO ELECTRONICS ON/GEAR NEUTRAL. This will at least verify the starter is good, the engine turns freely, and the battery strong enough.

Remember, the "S" terminal is only a switch. When energized it actuates the internal solenoid plunger which closes the circuit between the starter motor and the battery.

 

SO Ive rechecked a few things, B terminal is getting solid voltage - 12.6 (I've charged the battery overnight some); connector on starter has continuity; S terminal is getting 12.6 when pushing start button.

Going to pull the IPDM and check things out in there. Could the BCM be an issue? I saw that included in the starting section of the FSM. I have a had some water on my passenger footwell from time to time the last few months. BCM is in that panel down there, could that be messed up now?

 

Possible, but not probable in this case. The BCM does two things:
- inputs the start request signal from the start button:
- outputs the request signal to energize the starter control relay.

Being that you are getting voltage at the "S" terminal when the button is pressed indicates that the BCM is receiving the request from the button and transmitting the signal to the relay.

NEVER HURTS TO CHECK THE BCM CONNECTORS ANYWAY

Check the two starter relays in the IPDM/er (next to the battery). Could be a gremlin in there.

If battery voltage is directly applied to the "S" terminal on a starter the starter motor should run.

 

Well positive day guys, did some more voltage testing and finally figured out it was an improper ground to the block. Ground wire on the drivers side from body panel:frame to block had corroded a bit. Double checked and cleaned all ground wires I could find (odd grounding system on this car BTW) and boom started right up.

So in addition to checking terminal connections for corrosion also check all the ground connections as well.

I figure the bad ground slowly killed my OEM starter and strained the battery enough over time to kill it too.

Live and learn and thank you all for the advice!

 

Congrats! Glad you got it all sorted, up and running.