Charging/Alternator ?

Same thing happened to me with my 91 YJ. Turned out to be the voltage regulator which is part of the PCM. Required replacement of the PCM before the problem was corrected. I'm pretty sure that all YJs and TJs have the PCM controlled voltage regulars. Only way to fix it is to replace the PCM. Sorry for the bad news, they're pretty pricey. If you have a check engine light, there will be a code associated with it. My codes were 41 (alternator field), 42 (Automatic shutdown relay), 46 (Battery overvoltage). I have the 4.0L FI engine so there may be some differences from your 258,

4.2.

You are describing a dirty battery cable.

I would be checking the ground side first, the cable goes to the engine block and gets corroded there, then the next cable is a wire mesh one that goes from the rear of the engine head to the firewall, this one is most likely the bad one, but...

I also have seen the alternator bracket itself lose the ground. You can check this by using a booster cable from the battery negative to the alternator case. If the volts stabilize you have found it.

The other one that will cause those symptoms is a dirty connection on the starter solenoid on the firewall. The alternator wire and positive battery cable connect there and get dirty really easy.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Daniel Paisley wrote:

He is lucky, Chrysler hasn't aborted the charging system yet on his 258, he still has a 'real' alternator.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

rec>

Mike, isn't there also a wire ground around the emergency brake pedal mount that sometimes causes this problem?

What's the real one on the 258 ? (the tj one is 117 amp - seems ok)

Dave Milne, Scotland '91 Grand Wagoneer, '99 TJ

That one grounds the fuel pump in the 4.0 engine version. He still has the carb engine with the mechanical pump.

Mike

rec>

They only put half the charging system in the 'cheap' round thing under the hood they call an 'alternator' in the Chrysler YJ's and TJ's.

The rest they put into a $300.00 to $2000.00+ (depending on wrecker source or new) computer under the dash.

On the AMC Jeeps, they used an 'all in one' alternator with a 'built in' regulator.

Chrysler didn't like these units because it only costs $25.00 to get a full rebuild kit for them including the bearing and they are dirt cheap to buy. I recently got a 5 year warranty one for just over $100.00.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Dave Milne wrote:

Re: Charging/Alternator ? Group: rec.autos.makers.jeep+willys Date: Sun, Dec 12, 2004, 9:32am From: snipped-for-privacy@staffnet.com (reconair) Same thing happened to me with my 91 YJ. Turned out to be the voltage regulator which is part of the PCM. Required replacement of the PCM before the problem was corrected. I'm pretty sure that all YJs and TJs have the PCM controlled voltage regulars. Only way to fix it is to replace the PCM. Sorry for the bad news, they're pretty pricey. If you have a check engine light, there will be a code associated with it. My codes were 41 (alternator field), 42 (Automatic shutdown relay), 46 (Battery overvoltage). I have the 4.0L FI engine so there may be some differences from your 258,

4.2. Scott _____________________-------__________________ Dude, don't scare me like that :-)

Re: Charging/Alternator ? Group: rec.autos.makers.jeep+willys Date: Sun, Dec 12, 2004, 10:25am From: snipped-for-privacy@sympatico.ca (Mike=A0Romain) You are describing a dirty battery cable. I would be checking the ground side first, the cable goes to the engine block and gets corroded there, then the next cable is a wire mesh one that goes from the rear of the engine head to the firewall, this one is most likely the bad one, but... I also have seen the alternator bracket itself lose the ground. You can check this by using a booster cable from the battery negative to the alternator case. If the volts stabilize you have found it. The other one that will cause those symptoms is a dirty connection on the starter solenoid on the firewall. The alternator wire and positive battery cable connect there and get dirty really easy. Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's ___________________________________________ Mike, I checked the negative ground on the block before I posted, my bad for not saying so. I never thought about checking the mesh wire going to the firewall. I did find corrosion on the electrical plug that goes to the alternator and sprayed it with some CRC electronic cleaner. Now then, if the alternator bracket itself has lost 'it's' ground, how does one help it 'find' it's ground again? TIA, Dan

The easiest way is to cable the thing. You can get battery cables with

2 loop ends and go from a bolt on the bracket to the bolt on the block where the battery cable hooks up. Taking off the bracket to clean it is a real pain.

Which plug are you talking about that you found the corrosion?

You have what is called a 'one wire' GM alternator on there. It has the plastic plug with two wires in it and the red wire jumpered from there to the alternator power post right?

The small wire, usually brown, sometimes yellow is the trigger wire. This comes from the coil power wire and is tied in on the 12 volt side of the ballast resistor wire up near the brake booster in the harness.

If this is the 'dirty' wire, then your alternator might not be getting the excite signal right away so it waits until high rpm (or heat helps the connection) to turn itself on. This is how the 'one wire' feature works.

And don't forget the battery cable to the solenoid relay on the firewall. That is a sneaky spot for a dirty connection.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's