I'm here again... I've been blessed with a handful of nasty Electrical issues lately. 2003 6.0 auto KR. Ign turns on, dash comes on like normal, windows & lights all work, vacumm pump works.. Thats it. Starter turns well if I hotwire it. Other then that she's dead. No buzz on inj when ign is on. OBD port has the power on blue/white wire but rest have none. Scanner says can't connect. Fuel pump doesn't run. Starter doesn't crank. All fuses have been checked. Checked with test light on all the engine related fuses and they all light up. Relays have all been switched around. Tried another used PCM to test. Unplugged fan, ebp, map, maf. My brain is going on overload trying to get all these electrical issues fixed. I much prefer a HPO leak or inj going bad, that I know how to tackle. I hate electrical. Thanks!!

 

To begin with what is your available voltages?
Below 8v almost nothing will work.

 

Batteries are full. Starter cranks fast when hot wired. I didn't specifically test voltage under dash.

 

So part of your circuits have power and others do not.
By the way throw the test light away it will light with only one vlt but your equipment wont work.
Worst thing to use troubleshooting a computer controlled system.

 

Yup. I believe so. I think connection is broken between ign and engine control (PCM) some where. Where on PCM do I check for power?

 

Start at the fuse box with a vl meter and go from there follow the current stream

 

OK. I'm going fishing tomorrow for the weekend so I'll tackle it Monday.

 

Keep in mind there are 3 basic types of circuits. Allways on;key on; start run.

 

Do you know which are the colors of wire and easiest place to test where the power loss to engine is? All engine control is gone. Or is that a bit hard to point out on a forum?

 

So no power at the OBD port? check the cig lighter both are on the same circuit/ fuse . what is V-ref value? ( Vehicle reference Volts).

 

Follow the smaller red wire from the passenger side battery down toward the starter. There are a couple of fusible links down there. Worth a look.

 

they all have power.

 

Just the one that is constant power. None that is activated with ign.

Next on the list is to check v ref.

 

Vref is a common circuit to all sensors and actuators. One bad spot in the circuit will affect all, even to a no start. The test of vref is long and involved.
The test procedure in the PCED maual takes a lot of time. You basically unplug all then test one at a time all the different tests. then move on to the next.
All I can say is happy hunting.

 

Is there a complete list of all the sensors in this v ref thing? I have MAP, fan, EOT, ECT, oil press, EBP, MAF, EGR, GPM, VGT, A/C press. all unplugged. Only volts I get under the hood KOEO is 1.4v on MAf, egr, fan. injector plugs get .6v. No other power on sensors that I mentioned unplugged above. What other sensors do I need to check? I also went over the harness and checked for damage. None to be seen.
I checked fuses under dash with v meter and all that are related to engine function have 11.8v with key on. Double checked fusable links on pass side coming from batt and they all have 11.8v as well.