Reneenay444

First and foremost: Thank you for taking the time to read my post; I really appreciate your time and help with my Jeep's issue.

I have a 2002 Jeep Grand Cherokee; it was purchased used in 2011. It seems something is always draining my battery. This happened once before...Pep Boys replaced the battery and starter about a year-and-a-half ago. Now, the same problem yet again. I just had it to the mechanic, it passed state inspection, no visible mechanical issues per the mechanic. A week later....

If the battery is charged up, the Jeep runs fine. As soon as I turn off the engine, it will not restart. No lights, or power of any sort.

Alternator? I do not know

Any advice is SO appreciated!! Glad to have discovered this forum.

dzeinert

I'd replace the alternator, return the battery for a new one and go from there. I would bet on the alternator being bad.

Bustedback

If the alternator was bad the engine would not stay running. Have the battery load tested and clean the terminals.

5-90

Fine my writeup on testing main electrical (battery, alternator, starter,) and follow it.

Stop relying on parts house "test benches" - calling them "****e" is the faintest sort of compliment (I used to work on the wretched things.)

dave1123

MY program for finding a drain problem involves disconnecting the battery, reconnecting it and seeing if it sparks when you do. With the key off, there should only be about 1 1/2 to 2 amps draw for the PCM and radio memory. Any more will give you a good spark. Start removing fuses one at a time and retesting. When you find only a very tiny spark, you've nailed it.

IMO, there is a bad diode in the alternator. This will pass current thru the winding to ground when off and will still show a charge when running, although not to capacity. If this is so, a good multimeter will show the presence of AC in the DC output. You may have to pull the alternator's wires off to isolate it.

I'm sure 5-90's write-up is good, but I sometimes find searches difficult.

5-90

That's something that was workable for the "good old days," but it's not something I'd recommend doing with a more modern vehicle, loaded down with electronics.

Transients, you know. Repeated transient spikes can do ugly things to solid-state electronics.

The variation on the above that I'd do would be to connect an ammeter between the battery & the lead (an ammeter must be connected in series,) then pull fuses one at a time until you see the ammeter drop significantly. Wait about 30s between pulling fuses, don't worry about putting them back until you find the one that gives you the big drop (unless you're going to lose track of where they go.)

You may get an occasional transient this way, but it's far less likely to affect the whole vehicle, it's going to be a lot smaller, and if you do damage anything it should be rather less.

Do not forget that "modern" vehicles (starting in 1974, but getting progressively worse, with a major leap in the early 1980s, with the inception of OBD-I) are laden with solid-state electronics, and solid-state electronics are painfully easy to screw up...

dave1123

Okay, 5-90! You got me! I AM 69 years old and am an old fart. I never gave transients a thought but you are right. I once suggested using a multimeter and the poster didn't have a clue what I was talking about! So I tried to keep it simple. So give me a head slap, will you?

5-90

*thwap!*

"Back of the head is discipline, a slap in the face is an insult."

Yeah, I'm an old-line mechanic myself (started when I was a kid, working on mostly pre-74 stuff with no real solid-state electronics to think of,) so I understand the shift that has to be made.

One of these days, I'm going to write up everything I've had to learn...

dave1123

Yeah, me too. I worked on my first engine rebuild at 16. Now if I can just remember what I've learned................

Oh! Yeah! I don't know everything!

AubieJeep

I'd clean the terminals. My voltage meter on the dash was going up and down slowly the other day and I could notice a faint flicker in my headlights. Also, sometimes it would get juice and crank, other times it wouldn't. Took the terminals off, cleaned the posts and contact points on the terminals, got em good and tight and it's fine now.

dave1123

I had this problem on my 97 ZJ. What I found was the smaller of the two terminals, don't remember which, the clamp end was stretched enough so the ends at the bolt were touching and not clamping tight. I took the bolt out and shaved the ends with a Dremel so they had a space between them again. Worked for me!

Reneenay444

Thank you for all of the replies - I appreciate the advice.

My Update: I replaced the alternator, got another new battery - now the starter is bad - clicking but not turning over. Hoping the starter gets here tomorrow.

While I am at it, I am going to replace the spark plugs, air filter, and oil & filter change. After all of this, I really hope it runs like a champ for a while.

Thanks again!!

dave1123

Yeah! Good luck with that.

On the plugs, stick with Champion Copper Core.

jroeiii

Had the same issue a few years ago with the click click starter, leaving me stranded a couple times. After two starters and batteries and even a tow to the dealership to change the started it turned out to be corroded connections at the battery terminals.

Clean the terminals with some terminal spray. I also used a dremel lightly to shine the posts / wires. Net make you have a good + and - to crank the starter.

Silly thing but it was the ONLY time in 10 years my Jeep left me by the side of the road.

dave1123

Ya wana go back and read post #11 again?