Re: 4.7 no start help PLEASE!

Date: Wed Aug 29 2012 - 15:07:24 EDT

original had 'no bus' error.
replaced cam sensor
figuring worth a try to get injectors going, same for crank, neither had
any codes saying were bad, but cheap so....
I only see
2 grounds for the PCM, c1-32 & 33 I think, but as you said, seems like
everything else would be dependent on those grounds
dunno of OBDii scanner can tell me if security is
ON? or do i have to goto dealer (not gonna happen without
I can call rebuilder but they don't seem to have very
smart folks working there... wouldn't recommend anyone buy from
been like pulling teeth to get them to make good on warranty!
they have a F rating with BBB....
wish I had known when
I ordered it!

> On Tuesday, August 28, 2012 10:03:32 PM you wrote:


>> PCM's are both Refurbs, 1st was junk, but

>> last two do exactly the same thing, so unless it were the issue
of the

>> security system shutting it down, I doubt it's that


> Whoever refurbed them should be able to tell you if the security
system is

> active, at least from what I can read about it in the FSM. I'd

> they'd

> turn that off unless you told them you have the security keys, and

> then,

> they'd have to have programmed it with the key codes.


> What was wrong with the original PCM that it needed to be



>> god 1w2v at

>> injectors, will run a test on the side going to the PCM to
ground, but

>> i'm

>> pretty sure there is none... question is why?


> Having not done this myself, I'm only guessing from the schematics.


> would have to have a good connection to ground for this circuit to

> But

> it looks to me like the PCM would have to have a good connection to

> for

> other stuff to work, too. Still, if the +12V side is good, then

> problem

> would have to be on the Ground side.



>> i've unraveled the

>> engine harness looking for any sign of melted/crossed wires,

>> confirm

>> connection on the lines going to the PCM, but doubt it's that
cause they

>> are ALL dead, if only 1 cyl was dead i'd say 1 bad wire...


> Yeah, that's what I was thinking too. If you had one dead, it'd seem
to be

> a

> problem in the wiring to that one. But all dead seems unlikely,
unless, as

> you

> said, the PCM just is refusing to fire the injectors because it

> think

> the engine is running or something like that.


> You mentioned replacing the cam and crank sensors. Were they bad, or

> that

> just a shotgun attempt? I'm assuming the PCM uses them to decide if

> engine

> is spinning and whether (or not) to fire the injectors. Is the wiring

> these two making it back to the PCM ok as well?


> Does anybody know what else the engine uses to decide if the engine

> running?



>> I see the

>> cap's on the 12v line too? prob. to stabalize voltage, if bad
prob go to

>> a

>> short...


> If it shorts, I'd expect it to go up in smoke, or for you to have no

> I'm

> not sure what would happen if it failed open, but I can't see how

> would

> shut down the injectors if it did. But I also don't understand what

> doing

> in the circuit.



>> truck has no security system, just a door lock

>> clicker, but as I had been reading online, somehow there can be
an issue

>> if you get a PCM that has security turned ON, and install it into

>> truck

>> w/o it???



>From the "SKIM" description, yeah, if the PCM is expecting
security key

> information from the sensor, and doesn't get it, the engine would

> then

> quit after a couple of seconds. I don't think that's your problem,

> since you're not getting the "start" or "run for a
couple of seconds"

> parts of

> that description.






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