sibleyg

Got a new unusual problem with the 7 recently.

I have a no start problem, no power. I read 2.5 V at the power dist box (where the high amp fuses are).

Got 12.5V at the battery, battery tested, no dead cells, holds power fine.
Checked battery to power dist box line, full continuity, reads 12.5V when unbolted from the power dist box.

Disconnected power dist box lines to alternator and starter, still 2.5V. Pulled starter and it works fine on a 12V source. Solenoid fine, bendix pops out and spins. No dead spot on the starter.

Grounds are fine. Left engine block, upper and lower intake, exhaust all fine and no evidence of short burning or corrosion.

No blown fuses anywhere (power dist box or inside fuse box).

Checked power dist box connections (bolted ones), all fine.

Checked driver side power harness, no pinched or frayed wires.

Pulling out my hair here. Can't find what is shorting the power down to 2.5V. Can't understand why the fuses are not blown if there is a power to ground short.

Any advice is appreciated. Respond here or wraithrx7<AT>yahoo.com.

Thanks!

mad_7tist

you are going to have to be more specific as to where exactly you are measuring including what you are using as a ground for each test.

so the starter does not spin. do any other acc like the lights/dash turn on?

is the battery relocated? how is the ground on the battery itself?

moconnor

iTrader: (14)

Also confused by above. "Still 2.5V" makes no sense to me in the context. What is?

AzEKnightz

iTrader: (24)

So from the battery positive to the power dist box is ok. BUT AT THE FUSE it is showing 2.5v? If so, why not check the ground at the dist box? OR simply remove the distribution box and look for signs of corrosion or loose connections. Sound like it is right there.

To me if the power cable is fine, it must be a connection or ground that's hooked up to the dist. box is neither corroded or bad/loose connection.

-AzEKnightz

AzEKnightz

iTrader: (24)

Also, please state where you are measuring the voltage from. Is it the 120amp main fuse and you have 2.5v?

-AzEKnightz

AzEKnightz

iTrader: (24)

moconnor, I believe he thinks that either the alternator or starter is internally shorted causing the system to pull it down to 2.5v. However after removal, it didnt read 12.5v or battery voltage and he's confused and it "still 2.5v".

-AzEKnightz

sc_frontier

iTrader: (3)

2.5v indicates a bad/highly resistive connection somewhere. If there was a short in the system, the battery would read much lower than 12.5v most likely. If you were to ground the positive lead of the battery, for that split second there would be 0 volts at the batteries terminals (assuming you grounded the terminals with a bar that had the same resistance as the batteries internal resistance).