anomoli

Hello, and Merry Christmas and happy holidays to all.

I have a '97 Cherokee 4WD with auto trans and 140k miles, that has a problem that started recently, and I am seeking advice.

First, it was overcharging, alternator light coming on, and when it did, it would no longer downshift at a traffic light. I could shift it through the gears and get going, or I could turn it off and restart it and everything would be fine for awhile.

I replaced the alternator, as well as the PCM, but it was still doing it. I later discovered that the negative battery cable ground had broken from where it attaches to the fender, which I replaced. But it still had these problems. So I took it to an auto electric shop.....and everything was fine, as far as the electric goes. I drive it for a few days...and it starts again...shut off vehicle...everything is fine after restart.

Lately the electrical problem stopped, and the downshift problem was occasional. My transmission guy says he thinks it is the shift regulator, the small computer box next to the gas peddle.

This past Friday night, I drove it all over town, and it was fine. The next day...alternator light, downshifting problems.

To make this long story short, I think I have 2 problems. One is a bad ground somewhere in the electrical system, the other is a computer related downshift problem, or are they both related? The problems started at the same time. It seems to do these things more when the weather is warmer, Last Friday night we had cooler weather here in S Fla.

So..any of you knowledgable Jeep people know what is up with this thing? I like this Jeep, would like to drive it for awhile.

Thanks in advance.

96Cherokee113

Merry Christmas and welcome to the forum. The two problems could be related. It could have been a short from the bad negative cable grounding out on something that caused an electrical problem with the so called shift regulator. I'd say change out the shift regulator if it's coming from a certified and trusted mechanic. I don't know much more than that though and I drive a manual so I don't have these problems. I'm sure someone will have more insight on this during the day after everyone wakes up. Good luck and Merry Christmas.

Mike1998XJ

Have you put a meter on the battery leads when the light goes on and seen what the voltage is? if the Alternator light is still coming on you still have an issue with the charging circuit somewhere... Maybe even the "new" Alternator. The light coming on does not necessarily indicate an over-charge situation.
Did you have the old alternator bench-tested? If so what was the result?

How is the engine block ground wire to the firewall? those can become severed from the main wiring harness rubbing against them. Look behind the wire harness.
Post the voltage on the battery the next time the light comes on.
Does the belt happen to scream when you start it or when the light comes on or when accelerating? If so it may not be tight enough.
When you replaced the battery-to-fender ground did the screw tighten all the way or was it overtightened and now it doesn't hold the wire tight to the fender? If so drill a new hole, wire brush it and screw it in there. Check it by wiggling the wire vigorously and see if it loosens up. A bad ground can cause an intermittant issue like yours.
Mike

anomoli

Hi Mike, and thanx.

The overcharging occurred when the light was off, reading 18 volts. After two alternators including bench test, (they were bad) and the new $240 dollar PCM which supposedly contains the voltage regulator, and the replaced ground wire, my auto electric guy said everything was fine, and could not get any sign that anything was bad, used almost a half a tank of gas running it all day.

Not only was that ground wire broken but it was poorly attached to the fender, and it is now tight. I will check the firewall connection.

Also, sometimes before the alternator light comes on, the headlights start "flashing"..bright to dim, and the radiator fan will speed up.

Now, I still have this downshift problem, and I saw on another forum somewhere that the transmission cable from the throttle control may be sticking, but that seems fine. Question, could a bad ground/firewall connection cause this computer transmission shift regulator to act up, as well as these other problems, or is that a different situation?

Last night my daughter drove it, had a downshift problem on the way to her friends house, but no alternator light, no flashing headlights.

No problem at all on the way home.

This is driving me nuts...the sun is up, going to check grounds and replace battery terminals.

anomoli

Ok...so I go out this morning, start the Jeep, alternator light is on, and I can hear the fan running fast. I pop the hood, and start fooling with the grounding strap at the firewall. As soon as I pull on it a bit, the fan slows down, let go, it speeds up, pull on it, slows down.....

So I disconnected at the fire wall, crimped on the connection, then twisted it up a bunch of times, to add a bit of a tighter weave, and reconnected it. (But I bought a hunk of negative cable from Advance Auto just in case). I also replaced both battery terminals, the negative one was funky. I started it up, and played with the grounding strap, seemed fine.

Then I took it for a 12 mile test ride, first up I 95, then back through traffic. No downshifting problems, no alternator light.

So Mike you were correct.......and thanx!

Gonna keep my eye on it though......