Jeep Nasty
Active member
- 379
- 244
- 43
- Location
- NH
All right, I’m a bit stumped on some alternator and battery wiring on my truck that I just got.
It’s an M1088A1 with the cat 3126.
The previous owner has done some tinkering with it and I’m just trying to figure out a baseline before I do anything worse.
The wiring on the alternator had the black wire shown connected to the ground but that has the metal tag on it still prior to the extension that was added of TL 35, which, according to the wiring diagram, shows that that should be connected to the regulator and not the ground .
Then I have this white wire, which seems odd since most of the military truck wiring is black with metal tags, and there are no numbers, stamped or tag onto this wire, which was connected to the energize circuit of the regulator.
With the ignition on, I showed no voltage to the black wire and I show approximately 16 V to the white wire with the engine started and running. I don’t show voltage to either of them.
if I go into the circuit board or power, distribution panel, the LED for the K 11 excite circuit does not illuminate when the truck is running or when the ignition is turned on, but it will illuminate while the engine is cranking.
The circuit breaker 77 has been replaced with a 10 amp fuse, which is the correct load but I’m only showing 6 V when the ignition is on to that fuse but when the engine is running I am showing 24 V to that fuse
In addition to the alternator which could be part of the problem or completely separate the batteries have been changed to a two battery set up, and there is a manual battery disconnect switch, which does not look military in nature to me, but it’s only set up to disconnect the 24 V side off of the batteries leaving the 12 V side constantly connected .
I’m not sure if this truck was one of the ones that was supposed to be equipped with no battery disconnect or if it should have a different style one that disconnects both the 12 and 24 V circuit or does a manual disconnect of the ground.
I know on the cat 3116 motors you can manually excite the regulator and the alternator by bypassing the two wires coming out of the wiring harness and hooking into the 24 V side of the fuel solenoid.
I am wondering if this is the appropriate action to take with the cat 3126 motor or if this does not apply and I am wondering if both of those wires need to be connected to the regulator, and that neither of them was designed to be a ground.
At least that’s what it looks like according to the wiring diagram that I’m looking at for an A1 series truck any tips guidance links to relevant articles would be incredibly helpful. I would just like to ensure that the wiring is all done correctly before I start replacing parts
Additionally, if I place the white wire onto the excite side of the regulator with the ignition off engine, not running, I will get a red flashing light for the 28 V LED on the alternator regulator and I will get an amber flashing light for the 14 bolt LED on the alternator regulator but when the engine is running no power is going to that white wire so none of the lights illuminate.



Sent from my iPhone using Tapatalk
It’s an M1088A1 with the cat 3126.
The previous owner has done some tinkering with it and I’m just trying to figure out a baseline before I do anything worse.
The wiring on the alternator had the black wire shown connected to the ground but that has the metal tag on it still prior to the extension that was added of TL 35, which, according to the wiring diagram, shows that that should be connected to the regulator and not the ground .
Then I have this white wire, which seems odd since most of the military truck wiring is black with metal tags, and there are no numbers, stamped or tag onto this wire, which was connected to the energize circuit of the regulator.
With the ignition on, I showed no voltage to the black wire and I show approximately 16 V to the white wire with the engine started and running. I don’t show voltage to either of them.
The circuit breaker 77 has been replaced with a 10 amp fuse, which is the correct load but I’m only showing 6 V when the ignition is on to that fuse but when the engine is running I am showing 24 V to that fuse
In addition to the alternator which could be part of the problem or completely separate the batteries have been changed to a two battery set up, and there is a manual battery disconnect switch, which does not look military in nature to me, but it’s only set up to disconnect the 24 V side off of the batteries leaving the 12 V side constantly connected .
I’m not sure if this truck was one of the ones that was supposed to be equipped with no battery disconnect or if it should have a different style one that disconnects both the 12 and 24 V circuit or does a manual disconnect of the ground.
I know on the cat 3116 motors you can manually excite the regulator and the alternator by bypassing the two wires coming out of the wiring harness and hooking into the 24 V side of the fuel solenoid.
I am wondering if this is the appropriate action to take with the cat 3126 motor or if this does not apply and I am wondering if both of those wires need to be connected to the regulator, and that neither of them was designed to be a ground.
At least that’s what it looks like according to the wiring diagram that I’m looking at for an A1 series truck any tips guidance links to relevant articles would be incredibly helpful. I would just like to ensure that the wiring is all done correctly before I start replacing parts
Additionally, if I place the white wire onto the excite side of the regulator with the ignition off engine, not running, I will get a red flashing light for the 28 V LED on the alternator regulator and I will get an amber flashing light for the 14 bolt LED on the alternator regulator but when the engine is running no power is going to that white wire so none of the lights illuminate.



Sent from my iPhone using Tapatalk
