Not much of a way the starter could cause that. Of course a lot of the wires hook up there, so thats possible.
But, you checked that.
It sounds to me like you have a mechanically induced electrical problem. In other words, everything is ok until something moves.
Most likely is a ground problem.
First method of attack, is to find a way to reliably reproduce the problem in a situation that is conducive to troubleshooting.
Crank it in the driveway, try revving it up out of gear. Give it quick shots of power. If that does not do it, try loading the drivetrain.
If its an automatic, put it in gear and hold the brakes while you give a little gas. Manual, ride the clutch while holding the brakes.
If that does not cause it to act up, get someone to watch the volts, while the engine is revved up and someone jumps up and down on the body.
From what I have read, it seems to act up when its moving or in a load. I suspect that something is coming disconnected or is shorting out when things move around. If we can find what will cause it to malfunction, we can isolate the problem.
Another test, is to attach longer wires to your meter. Set it on low volts, hook one lead to the negative terminal of the battery, and touch grounded parts of the truck.
You should have no voltage. If you see more than a half volt or so, that part is not grounded properly.
Wait, you have two batteries.
Check for a voltage difference between the two negative terminals. I suspect you may have a bad battery cable causing the voltage regulator to see the wrong voltage.
The negative cables are the most suspect, but a bad positive one could give it fits also.
But, you checked that.
It sounds to me like you have a mechanically induced electrical problem. In other words, everything is ok until something moves.
Most likely is a ground problem.
First method of attack, is to find a way to reliably reproduce the problem in a situation that is conducive to troubleshooting.
Crank it in the driveway, try revving it up out of gear. Give it quick shots of power. If that does not do it, try loading the drivetrain.
If its an automatic, put it in gear and hold the brakes while you give a little gas. Manual, ride the clutch while holding the brakes.
If that does not cause it to act up, get someone to watch the volts, while the engine is revved up and someone jumps up and down on the body.
From what I have read, it seems to act up when its moving or in a load. I suspect that something is coming disconnected or is shorting out when things move around. If we can find what will cause it to malfunction, we can isolate the problem.
Another test, is to attach longer wires to your meter. Set it on low volts, hook one lead to the negative terminal of the battery, and touch grounded parts of the truck.
You should have no voltage. If you see more than a half volt or so, that part is not grounded properly.
Wait, you have two batteries.
Check for a voltage difference between the two negative terminals. I suspect you may have a bad battery cable causing the voltage regulator to see the wrong voltage.
The negative cables are the most suspect, but a bad positive one could give it fits also.
