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"resident smarty pants"
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You only get the negative signal if the conditions for the pcm are correct -- transmission range in neutral or park

Only the trucks with the keypad on the driver door has the vehicle security module -- this was stated the truck does not have
For that matter - when the Range Sensor is unplugged I do not get fuel pump operation either.
 

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Master BS'er
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You only get the negative signal if the conditions for the pcm are correct -- transmission range in neutral or park

Only the trucks with the keypad on the driver door has the vehicle security module -- this was stated the truck does not have
That might be right, I don't know. But I would be shocked if it didn't have some kind of anti theft. Usually built into the ignition switch and tied into the network from either the bcm or the cluster.
 

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You only get the negative signal if the conditions for the pcm are correct -- transmission range in neutral or park

Only the trucks with the keypad on the driver door has the vehicle security module -- this was stated the truck does not have
regarding ground search for pin4, the next step would be to search for the signal from the trans, which "tells" the PCM trans in P or N.
if the ground is then available it is certain that the problem is in the trans
 

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I suspect the range switch is bad -- the reason for the white ground wire on the added start relay
so you may not be able to get ground on pin 4 of the pcm

we need to know how the output from the range switch works, I have not been able to find accurate information on testing the range switch
one guy said it could be checked by voltage on the signal pin -- but he has not responded to me yet
 

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Master BS'er
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For that matter - when the Range Sensor is unplugged I do not get fuel pump operation either.
His ground for the fuel pump is up at the pcm. It's been altered. Probably because the pcm was bad. So they put a band-aid on it.
 

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regarding ground search for pin4, the next step would be to search for the signal from the trans, which "tells" the PCM trans in P or N.
if the ground is then available it is certain that the problem is in the trans
I suspect the range switch is bad -- the reason for the white ground wire on the added start relay
so you may not be able to get ground on pin 4 of the pcm

we need to know how the output from the range switch works, I have not been able to find accurate information on testing the range switch
one guy said it could be checked by voltage on the signal pin -- but he has not responded to me yet
We're getting out over our skis here again. One thing at a time guys
 

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For that matter - when the Range Sensor is unplugged I do not get fuel pump operation either.
That's interesting, I don't see anything in that plug that should affect the fuel pump
unless it is programming

Heading out to check my truck in other positions beside park and neutral
--fuel pump runs in all positions -- start only in park and neutral
 

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So does it send current to the relay in start position? Maybe it is the ignition switch or neutral safety switch?
 

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"resident smarty pants"
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That's interesting, I don't see anything in that plug that should affect the fuel pump
unless it is programming

Heading out to check my truck in other positions beside park and neutral
IMO it is part of the PCM programmed logic and application of the ground.

With all the twists and turns of this issue, all I am going to say is that I proved it out on MY truck - YMMV!!
 

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"resident smarty pants"
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So does it send current to the relay in start position? Maybe it is the ignition switch or neutral safety switch?
The 6.0L does not have a Neutral Safety Switch. The Range Sensor performs that function.

As I posted earlier - The Range Sensor is not a simple switch. It is a sensor hat sens a specific frequency and a specific duty cycle to inform the PCM of the gear position. How that translates to troubleshooting is yet unknown. The Manual does not give out any specific troubleshooting information.

Also - he has been able to get the truck to crank and even start with the Range Sensor unplugged (ie ignition worked - at least in this configuration).
 

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"resident smarty pants"
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IMO, we need to know where the wires come from for the fuel pump relay.

It is possible that the fuel pump relay power ties into the Range Sensors reference voltage circuit (which we now know that it is 12 volts). If so (AND if the range sensor is shorted out), this could potentially impact the voltage of that circuit when trying to start. That is just a guess though (and I am starting to lose track of all the scenarios of starting).

Maybe an even more likely scenario is that he tied into a shift solenoid VPWR circuit for the Fuel pump (YE/WH wire) and one of them is shorted out.

With all the wiring changes, that seems like priority 1 to understand.
 

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OK, what part do you want to work on first?
Doesn't really matter. Pick one and start at the bottom, work your way up a logical path.

I still don't even fully know the symptoms, which is the very first step. Put the truck completely back to stock. So, take the grounds off the pcm that were added up there. Now, what are the symptoms? No crank and no fuel pump? Do I have that right?

As far as the range sensor. First make sure there is no function of the relay, then move on to why.

Sent from my SM-G950U using Tapatalk
 

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Also - he has been able to get the truck to crank and even start with the Range Sensor unplugged (ie ignition worked - at least in this configuration).

but I had to use the wire and bridge terminals 30 and 87 at the starter relais port.
It did not work with the key


 

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"resident smarty pants"
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but I had to use the wire and bridge terminals 30 and 87 at the starter relais port.
It did not work with the key


So, I am getting more and more confused. On your VERY FIRST post on FTE you called it a "Crank No-Start". Had you jumpered the relay then? To me that indicated that you could crank the engine over when you turned the key to crank (which would indicate the ignition switch is ok)

Here is your post

2005 6.0 crank no start. "TBC fault" in dash. Fuel pump not running ( no fuel pressure, "crash botton" I´ve pushed). Curiously, I can't access the usual parameters (ICP, IPR, FICM,.....) to go on troubleshooting.... only these DTCs are displayed

Its an towing truck for cars, no possibility available to tow a trailer, why does it have trailer brake controller?

Thanks
and an earlier post here -

With everything hooked back up: injectors are clattering, engine cranks well, but fires not up. Wait-to-start stays on (this is to my knowledge an error message that something is wrong with the CAN.) airbag symbol flashes irregularly and disappears sometime later. "TBC fault" in dash display.

no cable damage can be detected. The truck was converted to a tow truck with crane in the USA. The electrical work is not very nice but not sloppy either. The truck worked perfectly, but died the first time months ago, the second time followed week later. The third time recently it did not start anymore.
Again, indicating a crank before the starter relay wiring was "jumpered" by you.
 

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So, I am getting more and more confused. On your VERY FIRST post on FTE you called it a "Crank No-Start". Had you jumpered the relay then? To me that indicated that you could crank the engine over when you turned the key to crank (which would indicate the ignition switch is ok)

Here is your post



and an earlier post here -
At that time the wh/rd cable was installed, the "man-made ground". For me the meaning of this cable was not yet assignable at that time. I apologize for the confusion.
When I removed the wh/Rd wire from the starter relay coil , I can Not crank with the key.
 

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"resident smarty pants"
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At that time the wh/rd cable was installed, the "man-made ground". For me the meaning of this cable was not yet assignable at that time. I apologize for the confusion
So when that WH/RD ground "jumper" was removed, it became a no-crank also.

That is what I thought.

My post above (responding to Tom Horn) was ONLY to address his question about the ignition switch. If it cranks, even w/ the WH/RD w/ the WH/RD jumper wire, the ignition switch should be good.

I agree w/ jamiesaun above - leave that WH/RD jumper off and lets go with a NO-CRANK, and a NO-START (no fuel pump).

From what I can tell, the other 4 wires to the starter relay come from the proper spot on the CJB relay slot.

Please verify that.

Then help us understand where the wires come from on the relocated Fuel Pump Relay.
 

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The 6.0L does not have a Neutral Safety Switch. The Range Sensor performs that function.

As I posted earlier - The Range Sensor is not a simple switch. It is a sensor hat sens a specific frequency and a specific duty cycle to inform the PCM of the gear position. How that translates to troubleshooting is yet unknown. The Manual does not give out any specific troubleshooting information.

Also - he has been able to get the truck to crank and even start with the Range Sensor unplugged (ie ignition worked - at least in this configuration).
Well that is what I meant the range sensor just couldn't remember the correct terminology. But anyway that would be my best guess a problem with the range sensor. Also I had this same problem with my 97 . The first time this happened the shift cable was out of adjustment , then it did it again and the cable was so shot it would not adjust. I replaced the cable and got everything in sync again.
(((Sync? On a Furd? :mad:))) But anyway just throwing that out there, that's what happen to me.
 

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Mark: Key on, now Fuel pump runs > engine runs. But I don't know why. I'll check again tomorrow. I'm afraid I don't have much time tomorrow, I'll report...

"From what I can tell, the other 4 wires to the starter relay come from the proper spot on the CJB relay slot."
Yes.
 

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This is getting confusing...how many problems does this truck have???? LOL
 
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