alternator compatibility

[FHerault]

Time to cure my alternator problems...
Will a 1999 alternator fit on my 97 pickup, bolt on ? I think they are rated 136 Amps and my old one is 120...
I did searches and if I've found lots of threads about alternators, nothing about the compatibilty.
It seems that there are few other upgrades but I'm on a budget now.

Thanks in advance.

 

[Timd32]

Why not just bebuild what you have?

Do you have a ton of added options? How good are your grounds, cables, starter solenoid and the batteries in general, all those will just cause the other stuff to work harder.

If you need more then what Geno's carries, I bought additional kit parts from this place after I smashed a part not included in Geno's kit.

https://alternatorstarterrebuildkits.com

 

[The patriot]

I dont know if it will fit.
As far as I know, the difference in years around ours is the way the factory harness connects to the alternator.
If you can get a pic of the 1999 alternator, if the connections are the same, it should work.

 

[BoeingDiesel]

Does the '97 use the voltage regulator in the PCM like the '99? If so, that may be your problem if it's a no charge at all issue. The '99 alternator uses a plugin connector. Is the '97 the same or have 2 lugs? Also, I'm guessing you have a 8-groove pulley which would be the same as the '99. You might want to have the alternator tested before you start throwing $$ at it. Been down this road only to find out it wasn't the alternator but the voltage regulator in the PCM had died.

 

[GAmes]

Have you checked the battery temp sensor? Exactly what are your alternator problems?

 

[FHerault]

Thanks for the advices.

My alternator was charging erratically for a few days, the in-dash voltmeter was showing under 14v and sometimes just above (warm engine). One week ago, while driving the red light ''gen'' went on, and off after 5 minutes or so. Now I have the voltmeter around 12v in the dash and the light ''gen'' comes on after 1 minute or 2 of driving, every time.
I have checked the voltage at the battery (driver side) while idling and it's around 12,5 volts. Even if I put light throttle (1500 to 2000 rpm) the reading does not change.
I've checked the battery cables and terminals.

For now and temporary I just slowly charge my batteries at night and just drive without fan, radio, etc...

All the alternators I've found locally cost around 200 CAD$ and, I assume, are remanufactured since they charge a core.
I've found some options in the US but the shipping cost are prohibitives.
But before throwing money in the alternator, I have to be sure it is the problem.

I have some auxiliary lights but nothing heavy, but I thought that if the 24v alternator was a bolt on light upgrade (120 to 136 amps) for the 12v at a similar price, why not ?

 

[GAmes]

The temp sensor can cause the alternator to charge incorrectly. I suggest you ohm it out before you buy a new alternator. I also suggest you get your original rebuilt if there is a shop near you. Parts house rebuilds are not very dependable.

 

[FHerault]

I'll check the temp sensor. I have changed my front L fender last summer so perhaps there is something wrong. Wich value should be obtained when testing the sensor ?

If the sensor is good, I'll have to check the alternator.
If the voltage regulator fails in the PCM, the alternator does not charge at all ?
Can this regulator be tested ?

Thanks !

 

[Timd32]

My 1996 book, 25deg C (75F-80F) should be 9k-11k ohm.

You might want to pick up a Factory Service Manual, my 96 is section 8C for charging, 8W is the wiring, 14 give some basic descriptions of the charging circuits.

There could be some changes on mine to a 97.

 

[JMalik]

I'll check the temp sensor. I have changed my front L fender last summer so perhaps there is something wrong. Wich value should be obtained when testing the sensor ?

If the sensor is good, I'll have to check the alternator.
If the voltage regulator fails in the PCM, the alternator does not charge at all ?
Can this regulator be tested ?

Thanks !

Per the previous comments I think you will find that the 1999 alternator uses an entirely different regulator system than the 1997. In my 1996 alternator voltage regulation is done by the PCM and your 1997 is the same family as my 1996. I encountered problems with my alternator at about 150,000 miles. The original Denso brushes wore to the point where they would no longer work properly. I have an automatic transmission and the worn brushes caused the transmission to go out of lockup. I had to get Denso brushes to make the alternator work properly. In your case I suspect you have a manual transmission. If you are noticing voltage irregularities I would just inspect the alternator slip rings and brushes to see their condition. Then if you find them in good condition go on to more complex solutions.

 

[JMalik]

Time to cure my alternator problems...
Will a 1999 alternator fit on my 97 pickup, bolt on ? I think they are rated 136 Amps and my old one is 120...
I did searches and if I've found lots of threads about alternators, nothing about the compatibilty.
It seems that there are few other upgrades but I'm on a budget now.

Thanks in advance.

To answer your question on compatiblility. I have a 1997 ram diesel manual and it only lists the Denso alternator. On checking the parts houses I note that in 1998.5 there was a move to a 24v engine which also marked the move to a new alternator which is not the same as the 1997 alternator. Different connections are shown in the pictures. So a 1999 alternator would not work on your 1997 ram.

I would recommend that you go on to YouTube and look up
Diagnosing Alternator Problems - EricTheCarGuy

This site has some great suggestions addressing trouble shooting and verifying a bad alternator. It is not unusual for connections to loosen over time or corrosion to create connection problems. The tests demonstrated at this site will help you identify problems.

 

[FHerault]

Thanks for the replies and sorry for the delay. Work and winter planning...

My alternator has been completely rebuilt locally for a decent price. The brushes were worn and the diodes were burnt.
I've put it in the truck this afternoon and all seems good (at idle since I did not drive the truck) with about 14,2 v (and 13,2 when the grid heater is cycling).