Help - 07 M35x in limp mode after disconnecting battery

[whitediamond642]

I have a 2007 M35x with 35k on it. Here's the scenario:

I disconnected the negative battery cable to replace a headlight bulb. I ended up taking the cable off several times because it turned out to be the ballast and not the bulb, but I removed both headlights to test and be sure before ordering.

Basically, the negative battery cable was off for almost a week while I got the bulb vs ballast issue figured out. I got the car put back together and made sure everything was properly plugged back in and now the thing is in "limp mode", or so I think.

It starts just fine and idles fine. When driving it starts out like nothing is wrong, but as soon as I give it more than ~10% throttle it falls on its face. It's like the throttle plate is only opening so far. It's acceleration is so slow I feel it's dangerous to drive, especially on the highway.

I drove it a little bit on the side roads to get a code to show up. The only one that finally did show was the P0603 Powertrain Control Module (Keep Alive Memory) code. Nothing else.

I cleared the code and tried the ECU reset procedure (the CEL blinked like stated in the directions, so I think I got it). Same driving results. I then tried removing the positive battery cable and discharging the remaining current by holding down the brake pedal. Reattached the cable and same driving result.

I called Infiniti, but they only told me to disconnect the battery. Beyond that, they wanted me to bring it in (20 miles is a long trip in the car's current state).

Does anyone have any ideas? The only other thing I can think of is perhaps trying the Throttle Relearn (name?) procedure, but I just wondered if anyone else has had this issue.

I appreciate any advice anyone can provide.

Thanks.

[richardinatlanta]

Make sure that it is not in Snow mode. Check the switch in the front console.

[whitediamond642]

The Snow switch is not on. I was really hoping it was that simple. Thanks for the suggestion.

I did some more investigating today and found through my code reader's live data feed that the engine is not going over 8.6% on the throttle position sensor regardless of the pedal travel.

Additionally, the SES light blinks very briefly (so brief that I missed it the first few times) when I push the accelerator pedal past the ~10% threshhold, but it does not store a code. The manual states that this may indicate an emissions issue, so I'm not sure if it's related or not.

I was thinking back to when I removed my headlights while testing/replacing the bulbs/ballast and I remembered that I attempted to remove the small ground cable near the passenger side relay box (I think it has the radiator fan, wiper switch, etc. relays in it). Well, I got a little aggressive with the 10mm bolt and the head snapped off. I ended up moving the ground to the next availble bolt that was attaching a bracket to the car. I sanded it down a bit to make sure there was a good connection, but I suppose I could have made a mistake or there's not a good enough connection. I'll drill out the old bolt hold, rethread it and see if that makes a difference.

The further I get into this, the more it looks like I'll have to take it to infiniti. That sucks.

Does anyone else have any ideas?

[lovemycarM35]

the car is still under warrenty no worries

[whitediamond642]

EUREKA!

Finally figured it out. I'm not sure how this issue occurred, but the ICC was somehow causing the brake switch relay to be constantly energized. I didn't realize it until I was just trying to turn the car to "on" and it started without my foot on the brake. I got out and that's when I saw that the brake lights were constantly on.

I narrowed it down to the ICC by unplugging both brake switches, which did not cause the brake lights to go off, then by unplugging the ICC sensor in the bumper. That fixed the issue. It wasn't actually in limp, but was seeing the brakes being on and only allowing ~10% throttle as a safety feature. I just thought it was in limp.

The car is driveable now, but I'll have to have the dealership look into the ICC.

LovemycarM35, you are correct that the car is still under warranty, but since I'm past the bumper to bumper I assume I'll have to foot the bill on the ICC myself. Anyone had any experience with warranty claims or other in reference to the ICC? I've read a few posts on it and it sounds like an overly complicated system. Does anyone know of a way to bypass it completely without it throwing a fault code (like it's doing on the car now)? It would be nice just to have cruise and not have to worry about getting it fixed since I've heard the laser sensor is ridiculously expensive.

Thanks again for all the help on this.