Searched around couldnt really find an answer. For some reason Im getting no power to my truck from the Driver side battery. is this normal? if I disconnect power from my passenger battery I get nothing, both batteries are new and have been tested. Ive checked the wires they all seem to be in good condition.

 

Batteries are connected in parallel. If they are both charged and connected, it will get power where it needs to go.

 

Check the cross-cable between the driver and passenger side, and the driver's side negative cable.

 

As mentioned, both batteries are connected in parallel. Either battery should be fully capable of powering the truck. If not, you have a bad connection somewhere.

 

But neither battery by itself is capable of STARTING the truck.

 

A single battery of the correct size can easily start a 7.3 in warmer weather.

 

When the right side (passenger) battery is disconnected is the left side (drivers) battery being disconnected unintentionally also?

 

Yes it is, also did some more trouble shooting. When the passenger battery positive cable is disconnected the truck will die, no lights, nothing just falls on its face. But the alternator is operating like its supposed to as far as charging the batteries.

If the truck is off and the passenger battery is disconnected I get no power at all even though all the cabling and ground seems to be intact. Is there a fusible link somewhere?

 

Few possible causes:
Bad driver's side batteey
Bad positive cable connection (check and clean corrosion on battery terminals)
Bad crossover cable between battery positives
Bad ground cable or connection on driver's side battery.

Get a long piece of wire, turn the key on, and remove the passenger battery. Take the wire and jump from positive to positive and then try from ground to ground.

 

Disconnecting a battery cable while the engine is running is a good way to fry a PCM, IDM or both.

All fusible links are downstream, fed from the main power junction terminal on the starter relay. Either the driver's side battery is bad, or its ground cable is bad, or the cable connecting the two positives is bad. You need to test (using a meter) each of those individually. You should LOAD test each battery, in isolation.

 

Right, the battery acts as a kind of filter and absorbs voltage spikes. I think it's possible to also fry diodes in the alternator itself. Electrical problems can get spendy.

 

Didnt know that about frying the PCM. Thats good to know.

I did some more tests on the driver battery this morning with a multimeter. With the Passenger battery out I have 12.3V from positive post to ground post. Also 12.3V from crossover wire to ground wire close to each post. At the cross over junction I get 12.1V with grounds at the passenger battery ground wire and using a body ground. Also have 12.1 at the starter and glow plug relays using body and frame grounds. Through all this though I have no power to the truck, turn the key and nothing not even a click. As said before both batteries are fairly new and have been load tested, the alternator has also been tested. Im about at the end of my troubleshooting tree here with no answers.

 

I've drawn out a basic schematic of your electrical system and some tests I want you to do with the passenger side battery disconnected.

I have 7 voltage measurements I want you to do, and they're marked out in green lines with a letter in the middle. The ends of the green lines represent the points where you should connect your multi meter to. The measurements between engine ground and battery post ground may seem a bit odd, but just bear with me - it helps diagnose grounding issues. Please reply with your measurements labeled with the respective letter from my diagram.

For making measurements to body ground and engine ground, you may have to scrape away a bit of paint/rust on both to get a good clean connection to your multi-meter probe.

Also, please excuse the crudity of the model - I didn't have time to paint it or to build it to scale.

 

Hey man got all the measurments. Im assuming on D, E and F you were looking for continuity so C+ means there IS continuity. Grounds were taken from multiple body and engine locations. So here they are
A. 12.4
B. 9.9
C. 9.9
D. C+
E. C+
F. C+
G. 12.4

Also I found this ground strap disconnected where does it go?

 

I didn't want continuity, I wanted the voltage, as it tells more information about the state of the connection than just continuity and helps pinpoint the issue.

Anyways, there is an issue. A, B, C and G should all measure exactly the same voltage. Based on your readings, it looks like there is an issue with your body grounds to the driver's side battery (the other readings would have narrowed it down further).

That ground strap should be attached to the engine block (and may "fix" your issue, as it will tie the block to the body). What I would do is find, inspect and probably replace the two ground wires coming off the driver's side battery. One goes to the block, one to the fender/body.