Not charging left battery?

[jvrotter]

I have a 86 M1009. Has been trouble free for 5 yrs or so, so i'm out of practice in repairs. Just noticed that the voltage indicator is in the yellow. Neither red alternator light has come on.
But when I checked my individual battery voltage, the rear battery reads 13+ and the front battery only reads 11.9V. I checked the voltage output of the left hand alternator and it reads same,11.9. Does this indicate the alternator is bad? I think that I had the right alternator rebuilt about 6-7 years ago but not sure.

 

[Dr.Jay]

I have a 86 M1009. Has been trouble free for 5 yrs or so, so i'm out of practice in repairs. Just noticed that the voltage indicator is in the yellow. Neither red alternator light has come on.
But when I checked my individual battery voltage, the rear battery reads 13+ and the front battery only reads 11.9V. I checked the voltage output of the left hand alternator and it reads same,11.9. Does this indicate the alternator is bad? I think that I had the right alternator rebuilt about 6-7 years ago but not sure.

First check the (Gen1 & Gen2) lamps. They should come on when you first turn the key on. If not replace the bulbs.
If the bulbs are good. Remove the Alternator and have it tested at your local auto parts store. (test it as an alternator for a 1978 Cadillac with MPFI). If it is an isolated ground alternator be sure they connect the ground clamp to the isolated ground stud.

 

[jvrotter]

First check the (Gen1 & Gen2) lamps. They should come on when you first turn the key on. If not replace the bulbs.
If the bulbs are good. Remove the Alternator and have it tested at your local auto parts store. (test it as an alternator for a 1978 Cadillac with MPFI). If it is an isolated ground alternator be sure they connect the ground clamp to the isolated ground stud.

If the bulb is burnt out, does that disrupt the charging circuit? Haven't had a chance to check yet as the weather is crappy.

 

[cucvrus]

I have a non working bulb on my M1028. I see that it is NOT charging where it is supposed to be on the gauge. If I use it cutting wood and never increase the RPM's it will never charge at the correct rate. So now I wait till the glow plugs cycle and the engine is warm. I increase the RPM's for a moment and the needle on the gauge goes to the top tick and the system charges as designed. I will work on it later. I think it is in the alternator on Gen 2. But it still works so I use it. Been on the highway everyday after work with the M1028. Hauling scrap to clean up my field and collection of antiquities. That trick doesn't always work but I had a truck with no cluster at all that charged perfect every time after goosing the RPM's one time.

 

[jvrotter]

How to access the bulb? Can I pull the front panel off and access it or do I have to get under the dash? Reason I ask is because i'm disabled with my right hand and would have a difficult time with my left. I did get under the dash and noticed that a plug is missing on that side and there is some kinda circuit sheet on the back. Now that I think about it, not sure if the left lamp ever lit up.

 

[cucvrus]

Easiest is from the back side. I do it from front side if I don't want to get involved in removing a fragile cluster. And if I am just changing bulbs to LED I do it from the front. But to do the entire cluster and clean everything you should remove the entire cluster assembly. Disconnect the speedometer cable with the angled frition lock and the cluster gently barely fits out of the metal dash. Very POOR set up for such a potatoechip/egg shell fragile assembly. Very Carefully and no pressure or snap. Good Luck. Been there done that several hundred times. maybe broke 1 or 2. The cable guide is an easy fix. let me know i will show. Fake it till you make it.