Community Forums

chollenback · 03-11-2018, 01:38 PM

Guys,

quick questions. I have a 95 Safari Sahara and it runs like a top except the chassis battery does not charge. I changed out battery and charged it and it purrs like a kitten. However, the battery still dies. I just changed alternator and there still is not power going to battery. It looks like connections are clean. Any idea on why battery will not charge when driving?

BFlinn181 · 03-11-2018, 01:47 PM

Have you checked that the alternator is putting out voltage? I'd then trace it at each place you can test it all the way to the chassis battery. It could be a large fuse in the cable between the alternator and the battery or something else, perhaps a bad isolation solenoid. It shouldn't be too hard to track it down if you do it methodically and step-by-step. Don't forget to check ground connections.

MSHappyCampers · 03-11-2018, 02:44 PM

Hi !

Welcome to IRV2! We're sure glad you joined the gang!

I'm far from being a mechanic, but I seem to remember that vehicles in those years had separate voltage regulators. Have you considered this?

Good luck, happy trails, and God bless!

Motor7 · 03-11-2018, 06:16 PM

I think Bflinn is on to something....my money is on the solenoid. They are housed in a box under the hood, usually on the drivers side. When you hit the battery disconnect button(to shut off and re-energize) do you hear a 'click'?

twinboat · 03-11-2018, 06:46 PM

You probably have a bad isolator.

The older units ran the alternator output to the center tap of the diode isolator and the side taps feed each battery, house and chassis. There was no mechanical solenoid.

Look for something that looks like this.

You should see alt voltage on the center and about 1 volt less on either side.
If your only seeing battery voltage on the chassis side, the internal diode may have failed. You can jump all three together, as a test, to see if you get chassis battery charging.

chollenback · 03-12-2018, 02:59 PM

I found isolator. It is a model 1202. Looks alot bigger than the picture posted but it does have the 3 posts. How do I test it to see if it works. I have been blessed to be mechanically inclined and fix anything but when it comes to electrical I am as dumb as a rock.

SO, I assume I start RV check from alternator back to starter and starter to isolator? When I reach isolator do I put digital meter on posts a certain way or just start touching digital meter probes to see if I am getting 14.8 volts. How can I tell if isolator is bad from digital meter?

Thanks for your guys kinds words on my arrival to IRV2. Once I tackle this then I will ask about cruse control not engaging

If it is the isolator then I will need some help to replace it - would hate to burn down RV.

BFlinn181 · 03-12-2018, 03:32 PM

The isolator diode should show the full alternator output on the center post. The output then goes to the chassis battery out one side terminal, and output to the house battery on the other side terminal. There will be about a 1 volt decrease at each side post. The diode should not allow any voltage from chassis to house batteries.

twinboat · 03-12-2018, 03:34 PM

First, the alternator output wire is not going to the starter like cars and trucks. It is going to the center of the isolator. Then from one of the outer terminals, It goes back to the starter.

Start it up and probe the 3 terminals with the positive. probe and ground the negative one.

The center should show alternator output. Each side should show about 1/2 to 1 volt less. One side is chassis batteries and the other is house batteries.

If it shows only battery voltage on one side, its bad.

OR Jump the center to either side and see if the chassis battery volts come up to 13 or more. You can even pile all three on one terminal and see if all batteries charge, as a test.

An isolator is a one way electric Tee. Power goes in the center and out both sides. Nothing can come back.

chollenback · 03-12-2018, 04:20 PM

I put red probe on middle post and grounded black probe to frame. I got 0 reading. I then put black probe on middle probe and touches red to each side. I got 12.5 on one side and 11.86 on the other post.

What does this tell me?

twinboat · 03-12-2018, 04:25 PM

It may tell you that the alternator wire is connected to ground, back at the alternator.

What brand alternator do you have. Some have 2, same size terminals and they could be crossed.

Don't jump the isolator terminals until you know that the alternator wires are correct.

chollenback · 03-12-2018, 04:37 PM

I went back out and retested to make sure. I grounded black probe on a clean metal surface. I put red probe to each one These are the readings.

1. left post was 12.48
2. Middle post was .46 (I confirmed 5 times and it is .46)
3. right post 11.86

Thoughts?

chollenback · 03-12-2018, 04:41 PM

I have this alternator. It is brand new.

New Alternator for Ford W/ Cummins FD1060 FD1460 Cat 3126 3176 3406 C-10 C12

it has 4 posts

1 post has no wires on it. Did not come with wiring diagram. I out it on just like the other wires were on the other one. Maybe other one was wrong?

chollenback · 03-12-2018, 04:48 PM

Not sure if these help. I did some attachments

chollenback · 03-12-2018, 05:29 PM

there are 4 post on back of alternator.

Ground - big black wire connected to it.
Bat - Big red cable connected to it.
R - little white wire connected to it (has a black plastic thing on it - you can see it in picture)
I - no wire attached.

Does this help