1997 QX4 intermittently won't turn over

[rjorgens]

Hi,

I'm a proud 1997 Infinity QX4 owner, it's been a great car and has 186K miles. I only found one other thread with a problem just like mine, and it didn't have a solution, so I'm putting this out there hoping someone knows where to start.

My wife asked me to come and look at the car, because it was running rough. I discovered a mouse nest on the intake manifold, and the little buggers had chewed through a couple spark plug wires AND a couple injector wires. I repaired them as well as I could, car was running fine again (this happened once before so I had a spare set of spark plug wires). Then my wife got stranded 50 miles away, car wouldn't start. It wouldn't even turn over. So I drove up there, wiggled my wire repair, and it started. Started 3-4 times after that just fine. We got it home, and the next day it wouldn't start. Manged to get it to start once by pushing in the brake, taking it out of gear, and putting it back into park. Then it starting working again, so I headed for the mechanic. Started up twice, but ended up having to have it towed to the mechanic. He repaired (better than I did) the injector wires, put a new set of plug wires in, and replaced the positive and negative battery cables. Car ran great for 3 days - now it won't start again.

Symptoms - starter does not seem to engage at all. Battery is full at 12.8V. All the lights on the dash light up, I hear what I think is the fuel pump start up, then absolute silence when I turn the key - headlights don't dim when I try to engage the starter. Because of that I'm thinking maybe it's a transmission lockout switch gone bad, or a security relay somewhere messing with me.

Any help is appreciated. Thanks!

[Ace2cool]

That's what I was going to suggest was the transmission lockout/neutral sensor switch. Other possibles could be the battery cables being loose, or corroded, starter motor wires loose or corroded, or the starter relay itself going bad. However, taking it out of gear and putting it back in park does make me think the neutral switch on the trans is giving you grief. Try checking the connection on that as well. Even check resistance on it while moving the shifter between park and drive with the car off.

[rjorgens]

Geez just realized I misspelled "intermittently" - sorry

[Ace2cool]

No worries. Fixed'd.

[Towncivilian]

Does the "security" LED light up when there is a failed start?

[rjorgens]

No. Here's the security light behavior.

No key in ignition, slowly blinking red.
Key inserted and turned to "ON" position - no LED.
After failed attempt to turn over starter - no LED.
When I remove the key from the ignition, it returns to slowly blinking red.

[Towncivilian]

The security system is working as it should, then.

Have you inspected the starter wiring for damage or fraying? Are both ends of both of the battery cables free of corrosion? Battery terminals shiny clean? Cables tight enough that you can't rotate them while they're on, but not overtightened to the point of cracking the battery case and causing unstoppable corrosion?

[rjorgens]

Yes, mechanic replaced both cables when I had it towed in. Car started fine for 3 days, now won't start again.

[Towncivilian]

Can you remove the battery and get it tested at an auto parts store?

[rjorgens]

Battery is fine, only 2 years old, voltage is 12.4 volts. Jumping it doesn't help.

[rjorgens]

OK, to let you know.

With the help of justask.com, an Infiniti technician helped me troubleshoot all the way through the inhibitor and security relays.
(also I downloaded the shop manual, thanks!) Ended up seeing 11.4 volts at the solenoid terminal on the starter when the key is turned. I took off the connector and plugged it back in, and it started right up. tried it 4 or 5 times, started every time. Next day, wouldn't start. So the next night I took off the solenoid connector (not easy) and cleaned it with flux cleaner (both sides). Hooked it back up and it started right up, tried it 4 or 5 times, started fine. Next morning wouldn't start.

So tomorrow I'm going to get it running and take it to the mechanic and have that connector replaced, and the starter replaced. I can't screw around any more, my wife hasn't had her car for over a month.

Hope this helps someone, if you get the shop manual you can follow the schematics and diagrams and figure what is going on.

[rjorgens]

Final result:

This time I didn't touch the solenoid connector or wire, I just tapped the solenoid a couple times with a hammer. Started right up. So its a bad starter, being replaced now.

Thanks for all your help!