Hello,
Well, all has been good for quite a while on the old van. Here is the latest. My 1992 1 ton 350 ram van with a 360 engine is not charging properly. The last few weeks I've noticed the ammeter seeming ok, then it changes. Needle at the same point consistently...then it drops down quite a bit. Not all the way, but quite a bit. The dash lights dim, if at night + headlights dim also. A few weeks of this, but van would still start right up and run fine. Sometimes the ammeter will not drop, sometimes it will drop. Kind of hit and miss. A few days ago, it dropped down and has stayed down. When I got home and tried to re-start van, it barely turned over...not even enough to try to start it. I had the alternator checked at O'reilly's today. It checked out OK. Where should I look next? Any ideas or advice would be great. Alt. is a 120 amp. Belts seemed nice and tight also.
Thanks,
Neb

 

The alternator could still be the problem. Since there is no problem at first, then the needle starts acting up, it could be a problem once the alternator becomes heated up. When you had it checked out, did you carry it in so that it was cold, or did they check it on the running vehicle?

 

Hello Alloro,
I brought it in off the vehicle. The last time or two I started the van cold, the needle was already down a bit. All the other times, I believe, the needle was OK then went down. But, the last couple of times, the needle was already down, right after a cold start. Wadda ya think?
Thanks, Neb

 

Most likely if it were a wiring issue the problem would be there all the time. You said the belt was nice and tight, so that shouldn't be an issue. This leaves you with a voltage regulator problem, which is built into the PCM, or a bad alternator.

If it were me I would change the alternator first.

 

I was kind of worried that it might involve the dreaded PCM. Is there any way to pin point what the problem is or am I going Las Vegas style? I ALWAYS lose! HA-HA!!
Thanks.

 

Do this test when it's acting up and the ampmeter is dowm.

NOTE:
Most alternators have two field terminals, one positive and one negative. With the
engine running, the positive terminal will have battery voltage present and the
negative terminal will have 3–5 volts less. Use a voltmeter to identify the negative
terminal before carrying out the following test.

Alternator Isolation Test:
On some models, it is possible to isolate the alternator from the regulator by grounding the field terminal. Grounding the field terminal removes the EVR from the circuit and forces full alternator output. This may help determine whether the problem is the alternator or EVR.

1. Connect a voltmeter across the battery terminals so the voltage can be monitored.
2. Start the engine and let it reach normal operating temperature.
3. Connect a jumper lead to a good ground.
4. Locate the field terminal (negative) on the back of the alternator.
5. Momentarily connect the grounded jumper to the field terminal.

If the alternator is okay, the voltage will climb rapidly. Disconnect the jumper before the output reaches 18 volts. If the voltage does not rise, replace the alternator. If the voltage rises, the regulator circuits are bad.

 

Thanks Alloro, I think I'm going to Vegas. It's 35* here with a stiff wind. I ordered a new alt. from O'reillys and will pick it up tomorrow and try to get it in before work on Thursday. Tomorrow is supposed to be mid 40's with less wind and more sun. I THINK I can deal with that!! Today?...I wussed out. I'll let you know if it solved the problem.
Neb.

 

Put on the new alternator today. A cool $156. Ouch! However...it seems to have solved the problem. Thank you Alloro...you were spot on with you're advice. I appreciate it! Hopefully, the van will run trouble free for awhile!
Sincerely, Neb