Well put. Thank you for the kind words and your appreciation. Take your time. I am not going anywhere. I am stuck on the east coast and after work, there's more at home so, anything I can do to help you I will. In the meantime, I'll just keep checking up here to see where your at.

CM

 

i did the test where i put a volt meter on the battery then checked voltage of th battery when cranking and it was 8 smthn. Didnt you say it should b 13.5? well if u did i took the alternator and it tested good.

 

So, to be clear here,

-you placed a meter across the battery, turned it over and saw 8 VDC, is this correct?

If so, that is a 4-volt drop under load which is on the high side of draw down. But, I think I know why. It's most likely the same draw down of ~3 volts but, since the truck hasn't been run in a while, what we are really seeing is a lower than normal power source. This is due to not charging / running it to achieve a full charge.

So, the question is, what is the battery output when under no load? Is it under 12 volts?

Does the truck idle at all or, is it possible that you can keep it running for a few seconds?

The reason you saw no increase in voltage was due to the fact that it wasn't running. I forgot about the fact that the ALT output is not directly connected to the BAT. It doesn't have built in rectification nor a voltage regulator. The PCM is where this occurs so, in order to see that 13.58 volt reading, it must be running vs. turning over.

So, your ALT checks out ok, but, the other half of the ALT CKT resides at the PCM level and, that's what this test will verify.

My err here- I simply forgot about that. See if you can keep it running just for a moment- long enough to obtain a reading at the BAT.

CM

PS: I am going to ask you this before I forget again:

When you finished installing your intake plenum and, after everything was reconnected: when you went to reconnect the negative terminal on the battery- did it spark when connecting it?

Reason why I ask this is: it is possible to inadvertently kill the PCM when connecting the negative cable under certain conditions.

Now, in no way am I saying that your PCM is fried but, that it's another possible root cause for this issue that could explain the sudden failure.

Once you verify that you've got ALT output (or not), we will have more to go on to support that possibility. If you have a scan tool, you can plug it into the OBD port and verify bus communication with the PCM at the very least to rule out that you haven't spiked / fried the input stage.

However, even if that checks out, it is still quite possible to have fried either the voltage regulator or rectification CKT at the PCM or coil driver CKT. This is why I want you to verify voltages. WE need to rule those out as possible failure modes.

 

If your timing is spot on,I would try starting it on propane.Actually I would use brake clean,since thats whats laying on my toolbox.If it starts up and runs,its got to be a fuel problem.If you have a jump pack,leave that on the battery while starting.You do have a serious voltage drop.If its correct,I dont see how your starter is turning.Usually anything less than 9 volts gives you the "click-click".Carefull with the brake clean,it will crack a piston if you spray enough of it.Propane is much gentler,but you have to be closer.I too am snowed in on the east coast CM.I have pushed enough F'in snow I am ready to move back to Miami.Oh well,gotta pay for thise new rims somehow....

 

i think when i first took it apart i grounded the wire that bolts to the back of the alternator and it arced to the casing of it. when i tried to check the input to the coil i cldnt get anything but there is spark at the plugs. i dont think i tested it right. what cld that arc do?

 

fry your diode trio at minimum,melt wiring,roast ecm.Electrics dont like spikes or unwanted grounds

 

This is why we troubleshoot all the systems. There's your root problem right there with that arc to case ground.

See, this is why I have to ask those kinds of questions because, there's always a little more to the story than what was originally presented. Here we have a fine detail that was not mentioned and, as always, the devil's in the details.

I am going to assume that you had the battery connected before connecting that ground.

This is an isolated ground (not case ground) that resides in a recessed, black epoxy shielded insert that resides on the rear of the ALT housing.

The only way that could possibly arc is if the power source (bat) was connected and, the electronics were drawing current and, since that ground was disconnected, this created an open CKT and no where for the current to flow to normally.

At the time of connecting this - thus closing that CKT, there was a voltage spike due to completing ground path on the ALT CKT at the PCM. The spike from the in rush current was seen in the form of an arc.

The results of this are catastrophic thus killing the components inside of the PCM- primarily the rectifier and regulator CKTs but, is not limited to just those two depending on what else is tied into that ground path as another CKT that ties into that same ground bus is the coil driver CKT. This CKT is responsible for turning the coil ON/OFF in sequence to the timing.

This is not user repairable (technically, anything is fixable but, not to the average consumer) thus requiring you to buy a new PCM.

You can get a top quality, lifetime warranty on one here from these guys: http://www.autosourcecomputers.com/

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Topic change:

If and when you tested at the coil: you certainly did not test it correctly as if, there's no voltage into the coil, there's no voltage that comes out. You simply can not put out voltage without something going in.

Since you saw spark- this means that it has to be working to some degree.

Let's do this:

Place the ground lead into test port labeled COM (common)

Place a paper clip around the red-lead and place it into POS (positive) on the meter.

Insert a paperclip from the BACKSIDE of the connector, to the POSITIVE wire at the coil. Should be orange if it's OEM.

Now, clip the COM to the headlight ground at the frame. May have to scrub through the oxide layers and or rust.

Now, turn the vehicle over and see if you see voltage at the input or not. Should read ~13.58 volts which is the same voltage that is supplied off the ALT CKT. IF it's below that value / around battery level- there's a problem at the PCM level and, in this case, I believe there is.

CM

 

ok well sounds expensive. i figured it was something computer related. Im used to working on older motors but i guess i gota learn the new ones sometime.i Will do that test. Would the dealers computer not pickup that the pcm is bad ?

 

Well, that depends on how bad it was damaged. Only if the PCM internal fault trips the OBD code will it show / read on a scan tool as a PCM fault. But, it's not 100% fool proof for, I have seen many replace them at dealers due to shorted Cruise Control switch.

How they test it is just as I had described to you- they will test the coil ON / OFF pulse as well as the voltage regulator output. In either case, if either one fails- this indicates a faulty PCM.

CM

 

ok i will retest the coil input. Im going to get a noid light and test the injectors too. YOur truck is badass