I know, I know..... Gen 2 light issues.

I have searched for this and haven't found my particular problem. After reading a fue posts and looking at the trouble shooting book as much as I could stand. I am at wits end. I have an 84 M1008 90k mi The gen 2 light comes on and stays on, and the gauge at best will sit right between the green and yellow. I have checked both alternators at all the plugs. With the truck running, the first alt is putting out almost 15v (analog multimeter...ugh) and the second is putting out 26v. The batteries are showing 26v with the truck running, but the gauge and light are still as previously mentioned. I haven't pulled the dash apart yet to see if I have some bad wiring there, all the fuse able links coming off the 24v junction box are good as far as I tested. I tested the side of the black spool away from the junction box. I am thinking about replacing the gauge set with auto meter speedo, tach (if i can find it) oil press, oil temp, coolant temp, and trans temp. But I would like to resolve this issue first. And I suppose ask if I will be frowned upon for doing such gauge work. Any help would be much appreciated.

Ej

You are probably just reading the total battery voltage of 26 volts at the rt alternator, the rt alt is prob not putting out any charging voltage

Engine off 24v at battery and alt. I don't get it. But then again wiring has never been my strong point.

thatguy84M1008 said:

Engine off 24v at battery and alt. I don't get it. But then again wiring has never been my strong point.

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You are reading 24v battery voltage to ground.

What is the voltage from post to post on the alt (not post to ground). Running and not running.



See this post by warthog. It is the simplest method of determining if the problem is with the truck wiring or the alt.

http://www.steelsoldiers.com/cucv/53017-gen-2-light.html#post606741

I read the post by warthog, I did check the 2 wire plug, and voltage is good there. You want me to check from where the 1st alt feeds the second to the output of the second?

A good alternator will put out ~14.7v.

If the first one is showing 15v and the second is only showing 26v total, then it is really only putting out 11v (15v+11v=26v)

It is time for a rebuild on the GEN2. More than likely it is the voltage regulator.

But for a few dollars more you can replace all the internals and install new bearings

Just went and checked what I think you meant. KOEO 12 ish volts, and same reading KOER Where can I find rebuild kits for them? And thank you for all your help. Where should I post my story and pics of this beast?

There are many post on how to rebuild the alternator. The Tech Manual covers it step by step.

You will want a kit/parts for a 27SI Type 100 alternator. You can ask for parts for a 1985 Caddilac.

I have purchased acouple of kits from this place....

High Output Alternators - Alternator & Starter Repair Kits - Alternator Parts - Delco 27Si Type100 Heavy Duty Rebuild Kit

It does NOT have the Isolated Ground replacement parts but you should be able to reuse the old ones. Just some bolts and fiber washers.

Awsome! Thanks!

thatguy84M1008 said:

Just went and checked what I think you meant. KOEO 12 ish volts, and same reading KOER Where can I find rebuild kits for them? And thank you for all your help. Where should I post my story and pics of this beast?

Click to expand...

With these readings it seems like your alternator is outputing 0v. The 11v you where reading are from the battery itself. 15 from the driver side GEN1 and 11v from the rear battery.

Time for a rebuild.

If you are not comfortable doing it most alternator shops can do it. They just need to be made aware of the neccesity of making sure the case is "isolated" from the internal electricals.

Almost all alternators ground the internal rectifier to the case so current will flow from the rectifier, thru the case, to the engine and back to the battery.

In the CUCV 24v system, this will not work and WILL let the Smoke Jeannie out of the bottle.

If you need more info, search for the Isolated Ground as there has been many threads post about it.