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RYANJGCL 11-07-2012 09:39 PM

P2100 OBD code - Intermittent Starting Problems
I have a 2005 Grand Cherokee Limited 5.7 and it's been having intermittent starting problems. When I turn the key, the starter cranks but the engine won't start. I'll be there 5-10min just trying until it finally gives in and starts. It's very random, sometimes 5x a day, other days once or twice, and other days no problems. Crazy thing is, when it does finally start, it runs PERFECT! I had AutoZone test my battery (its good), it can't be the starter because it does crank normally and eventually it does start. When it doesnít want to start I do get a code with the code scanner (P2100 - electronic throttle control motor circuit) I donít get any lights/codes when the truck is on. I really donít have a clue what it could be and everything I thought could've been the problem, I checked and ruled it out. I think that OBD code can be a clue. Anybody have any ideas? Has anyone had this problem?

xp29g 01-07-2017 05:40 PM

Re: P2100 OBD code - Intermittent Starting Problems
I have recently had the same problem with my 2005 WK 5.7. When it throws the P2100 code, I hold the throttle pedal down about 1/4 inch and hit the starter and it starts. It will rev to about 3000 rpm though, but settles right in to idle rpm. The service manual (Volume 3, page 9-884) has a detailed troubleshooting procedure that includes checking the throttle plate for ice or other obstruction, low battery voltage, and various open and short circuits between the control circuit from the pedal, PCM, and throttle valve assembly. The one common thing in all of the procedures is to 'use a scan tool and select the ETC (Electronic Throttle Control) RELEARN function'. This is something only the dealer will have.
I cleared my P2100 code and placed a mirror on the radiator support and began the start sequence. From the drivers seat, when I have the ignition switch in the run position, my throttle plate flutters a few times, opens about 1/4 inch, then closes to about 1/8 inch opening. Upon start, the throttle plate immediately closes up almost entirely, allowing enough air for idle operation.
There is a throttle position feedback circuit like a lot of vehicles have, and the service manual covers how to check for sweep voltage, closed throttle plate voltages, etc.
Sorry I can't provide more useful information at this time. Like your vehicle, once mine starts, it runs perfectly. If the no-start situation persists, I will have to look into it further. Just not in the cold weather. As long as the partial throttle position works when I hit the starter, I plan on doing that until warmer weather arrives.
I know this response is to an old post. But the information here may help someone to get by temporarily.

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