TJ Problem

hawaii · 04-14-2006, 12:56 PM

Parked my TJ for 2 days, got in to leave and it wouldn't crank. Battery was drained. Jumped it and drove home (40 minute drive). Got home, turned it off - realized I had my friends keys and had to take them back. Hopped in, cranked and no joy. So I figured shot alternator. Went to get my laptop and decided to see if she'd start up - joy. Alas, not yet. Now she won't stay on. The engine will turn over but just drops revs until it dies. Not overheating, there's oil, coolant and everything seems to be in working order. My TJ has always been a "hard starter" from I am assuming the fuel pump. Is it possible that it's priming enough to start but not keep it running? Could it be my TPS shutting the TB valve causing the engine to die? I'll see if I can get a code from it - in the mean time anybody have any suggestions as to what it could be or how to narrow it down some more?

Thanks!

Edit: The "hold odometer and turn key" doesn't toss any codes, however the "on 3 times" does work and gives me code 12 - which is "Direct battery input to PCM was disconnected within the last 50 Key-on cycles." Anybody have any idea what this actually means and how to fix it? I'm not sure this even affects my engine problems though.

**abnormal** · 04-14-2006, 01:11 PM

Quote:

Originally Posted by slayrose

Parked my TJ for 2 days, got in to leave and it wouldn't crank. Battery was drained. Jumped it and drove home (40 minute drive). Got home, turned it off - realized I had my friends keys and had to take them back. Hopped in, cranked and no joy. So I figured shot alternator. Went to get my laptop and decided to see if she'd start up - joy. Alas, not yet. Now she won't stay on. The engine will turn over but just drops revs until it dies. Not overheating, there's oil, coolant and everything seems to be in working order. My TJ has always been a "hard starter" from I am assuming the fuel pump. Is it possible that it's priming enough to start but not keep it running? Could it be my TPS shutting the TB valve causing the engine to die? I'll see if I can get a code from it - in the mean time anybody have any suggestions as to what it could be or how to narrow it down some more?

Thanks!

Edit: The "hold odometer and turn key" doesn't toss any codes, however the "on 3 times" does work and gives me code 12 - which is "Direct battery input to PCM was disconnected within the last 50 Key-on cycles." Anybody have any idea what this actually means and how to fix it? I'm not sure this even affects my engine problems though.

Sounds as if the alt is shot and your battery had enough juice after being jumped to get you home but is not holding a charge. Your engine, once started, uses the alt to run off of but if it goes then it relies on your battery. If your battery wont hold a charge your engine will run till your battery is dead. If you can get it to an auto parts store they can hook the battery thing up and load test your battery and also check your alt. Good luck!

edit: "Direct battery input to PCM was disconnected within the last 50 Key-on cycles."

This sounds as if your battery was stone dead and your pcm didnt see any power from it so it thought you battery was disconnected.

MDBLKRUBICON · 04-14-2006, 01:21 PM

I think the alt. dosen't charge at idle, only when the RPMs are around 1500+ (I could be wrong). I would try a new battery first.

fried_gold · 04-14-2006, 06:13 PM

It sounds like a dead cell in your battery, if it is you'll need a new battery. If you can get it started, see if you can keep it running by keeping it revved a little, like 12-1500 rpm.

I went to the store one day, went in for 30 seconds to get a newspaper, came out and the Jeep was completely dead. I got jumped off and it ran fine but it wouldn't idle. If I took my foot off the gas it would die, We jumped it off and I kept it revved up to get home.

I've worked at car dealerships before so I've seen hundreds of dead batteries, but none of them were like this so I thought my electric system was fried for some reason. I called my mechanic buddy and he said it sounded like a dead cell so I bought a battery and everything was good as new.

Jeepfreak911 · 04-14-2006, 06:29 PM

times 3 on battery. I had the same exact problem. time to upgrade to an Optima!!!

hawaii · 04-14-2006, 08:20 PM

Whee. I'll buy myself a yellow top tomorrow after I swap batteries to make sure that's my problem - too bad all the cars I own have GM-style bolt batteries instead of ones with poles. I can keep it alive by rev'ing right above the 1100 mark. Thanks you all.

Rob 99TJ · 06-05-2006, 08:37 AM

Quote:

Originally Posted by slayrose

Whee. I'll buy myself a yellow top tomorrow after I swap batteries to make sure that's my problem - too bad all the cars I own have GM-style bolt batteries instead of ones with poles. I can keep it alive by rev'ing right above the 1100 mark. Thanks you all.

was that your problem or was it the alternator or something else?

gevalia · 06-05-2006, 09:22 AM

Sounds like it might be a ground problem in the charging circuit. Check the engine ground and make sure it's okay and clean. Take it to Autozone or Pep Boys and have them wheel out the portable circuit tester. That will tell you if its the starter, battery, alt or not which might point to a wiring issue. Had the same problem 3 months ago on my 66 Fastback and it ended up being the engine to body ground strap. Alt, starter, and battery were fine.

**175MM BULLDOG** · 06-05-2006, 12:25 PM

Quote:

Originally Posted by slayrose

Whee. I'll buy myself a yellow top tomorrow after I swap batteries to make sure that's my problem - too bad all the cars I own have GM-style bolt batteries instead of ones with poles. I can keep it alive by rev'ing right above the 1100 mark. Thanks you all.

PepBoys have screw in terminals that adapt the screw types to standard terminals. I installed them on the side of my yellow top, and run the rig on them, with the winch hooked to the top posts.

jeepin_man · 06-05-2006, 01:00 PM

I say Battery, parts store will telly you in 5 min.

Rob 99TJ · 06-07-2006, 07:33 AM

I had been having starting/charging problems. I thought I'd have to replace the alternator. I went up to Autozone and had them test the battery and alternator. He said they were good and recommended that I clean the battery terminals. I was pretty skeptical but did it. Afterward the Jeep started up and I drove the Jeep around to let the battery charge up.

It's been fine ever since. I think my problem is solved for $0. I didn't think simply cleaning the terminals would make such a difference.

04-14-2006, 01:21 PM	#3
MDBLKRUBICON Registered User Join Date: Dec 2005 Location: Frederick, MD Posts: 121 Profile Gallery Classifieds My Jeeps	I think the alt. dosen't charge at idle, only when the RPMs are around 1500+ (I could be wrong). I would try a new battery first. __________________ 06' Rubicon

04-14-2006, 06:29 PM	#5
Jeepfreak911 Registered User Join Date: Dec 2003 Posts: 154 Profile Gallery Classifieds My Jeeps	times 3 on battery. I had the same exact problem. time to upgrade to an Optima!!! __________________ FlAT BLACK JEEP #1 98 Wrangler, 4.0, RE 5.5 LA,No front sway bar, Sye/Tom driveshaft, 4:56 gears, Super 35 with Detroit, "35" BFG, custom intake, Flowmaster, hella 500's throughout,Custom Warn shortened 4 inches each side front bumper,Flat Fender,Warn spare tire carrier. Hurculined tub. AC converted to on board air. I will be done soon.. i hope grrrr

04-14-2006, 06:13 PM	#4
fried_gold Registered User Join Date: Dec 2005 Location: US Posts: 628 Profile Gallery Classifieds My Jeeps	It sounds like a dead cell in your battery, if it is you'll need a new battery. If you can get it started, see if you can keep it running by keeping it revved a little, like 12-1500 rpm. I went to the store one day, went in for 30 seconds to get a newspaper, came out and the Jeep was completely dead. I got jumped off and it ran fine but it wouldn't idle. If I took my foot off the gas it would die, We jumped it off and I kept it revved up to get home. I've worked at car dealerships before so I've seen hundreds of dead batteries, but none of them were like this so I thought my electric system was fried for some reason. I called my mechanic buddy and he said it sounded like a dead cell so I bought a battery and everything was good as new.

06-05-2006, 01:00 PM	#10
jeepin_man Registered User Join Date: Aug 2005 Location: Sumter, S.C. Posts: 170 Profile Gallery Classifieds My Jeeps	I say Battery, parts store will telly you in 5 min.