Coder code P-0513, Vehicle stalls occasionally when coming to a stop-light or stop sign?

JAMIE HAMILTON

MEMBER
2004 DODGE DURANGO
5.7L
V8
4WD
AUTOMATIC
171,000 MILES

Have the vehicle listed above with a 5.7 hemi. The vehicle will randomly stall when coming to a stop. Not always but occasionally. I have had the alternator and battery replaced. It does not do it as much now but does still stalls. The check engine light is not on, but I was able to pull a code P-0513. The shifter also will not shift unless the brake is fully depressed while starting the vehicle. If you start the vehicle without depressing the brake, it will not shift out of park, then you have to shut off and restart the vehicle while depressing the brake. Brake lights work, there is no shuddering of the vehicle nor does it idle rough or cause the RPMs to jump. Any ideas on where to start looking now?

Things that have been checked:
Alternator and battery both replaced
Checked the under-hood fuse box
Checked transmission fluid
Brake lights work

1 Reply

CARADIODOC

MECHANIC
33,864 POSTS

P0513-INVALID SKIM KEY

For this code, there's many pages of diagnostic steps I can format and post for you, but it revolves around using the dealer's scanner. Let me know if you want me to do that. Near the end it asks you to try a different key.

For the stalling, you may have inadvertently made the problem worse by disconnecting the battery. When the battery is disconnected or run dead, the Engine Computer loses its memory. Sensor characteristics and fuel trim data are relearned as soon as you start the engine, without you even noticing. The one notable exception is "minimum throttle". That needs a very specific set of conditions for the relearn to take place. Until that is done, idle speed will be too low. The engine may not start unless you hold the accelerator pedal down 1/4". It will not give you the nice "idle flare-up" to 1500 rpm at start-up, and it will tend to stall at stop signs.

To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

During that seven seconds, the relearn will be aborted if the Engine Computer sees any change in signal voltage from the throttle position sensor, or if it sees the brake light switch turn on. While uncommon, that can happen if the brake light switch is out of adjustment and you're doing the relearn on a bumpy road. You can overcome that by holding the brake pedal up with your foot.

A different way to see this is to use a scanner to view "idle steps" under live data. The Engine Computer adjusts idle speed through the idle speed motor, aka automatic idle speed (AIS) motor. That is not a motor with brushes and a spinning armature as we normally think of them. This has four electromagnetic coils of wire that are pulsed with varying voltages and polarities to slowly rotate the armature to various positions. As it rotates, it retracts or extends a pintle valve on the end of a threaded shaft. That valve opens or closes a bypass air passage around the throttle blade. At the same time, it varies the length of time the injectors are pulsed open. Those two things together adjust idle speed.

The computer can place the AIS motor to any of 256 positions, or "steps". For a properly-running engine, step 32 is typical. With one misfiring cylinder on a V-8 engine, expect to see it at close to step 50. The important point here is if minimum throttle has not been relearned yet, you'll find it at step 0.