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No crank no start no communication with scanner


Aldo0280

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Well i already ran a new wire but the old wire is still there so i guess i can still test it but the alldatadiy flow chart thing i was following said to test the circuit 325 which is the wire from the pcm to the starter relay. But it said to test the resistance to ground & if it is more than 5ohms to fix the circuit & test for normal operation. The dvom im using just shows 600, 6000, 60k, 600k, 60m, when i tested it at anything less than 60k it would just show 0L or 0.L depending on where the setting is set. which is also what it shows if i dont touch the leads to anything? Before i ran a new wire with the meter set at 60k it was reading smthen like 13.4 but anything under 60k it would just show 0.L? Then after i ran a new wire it shows 0.L on all the settings? So i think there was possibly smthen wrong with that circuit but i still have no crank no communication. My thought was that possibly that wire might have fried the pcm? Now that the wire shows less than 5ohms i can move to the next step in the flow chart but it basically says after checking the trigger wire to the starter to replace the starter solenoid & test for normal operation but the starter is new & good i can get it to crank by jumping the starter relay but truck still doesnt start? So i never even tested that wire but i probably should just to be sure. The next problem is that the next step goes on to have me start testing the clutch pedal position switch which i dont think this truck has since its an automatic?
 


pentode

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Since you said the meter shows OL with the leads touching nothing and set to ohms, I’m thinking that probably means open loop, or no continuity. To measure that wire‘s continuity I’d set it to 600 ohms. Touch those leads together and make sure the display changes to read either 0 or something really low. (Just to make sure something’s not funky with the meter.) then measure that original circuit from the solenoid to the relay. If it says OL at that point then that wire is broken somewhere. Open circuit really shouldn’t have hurt the pcm.
the next thing I would check would be the relay itself and it’s socket but it would be nice to verify that control wire first.

EDIT: I must be sleepy because for some reason I thought we were talking about wiring from the pcm to the starter relay. You're working on wiring on the load side of the relay?

EDIT2: assuming you're doing that procedure in your screenshot, maybe another easy check would be to see if you can hear the starter relay clicking when you turn the ignition to crank? You could test with the meter and backprobing (or a test light) but that's probably very hard to reach - listening for the click is probably easier to start with.

I would also get back to looking at the integrity of the bus wiring as suggested before I showed up- once you make sure the meter is behaving
 
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bills4065

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Hopefully you have a 0 - 200 ohm setting on your meter. If so, that is the one to use. You are to measure the resistance between #6 and #14 right at the data link connector. It should be around 60 ohms. Let us know what you get. I myself disconnect battery before doing this check.
 

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pentode

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+1 you're definitely going to want to see if you can establish communication with the ECM since it all starts there. This Is step one in deciding whether you actually need to spend money on a computer
 

franklin2

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Well i already ran a new wire but the old wire is still there so i guess i can still test it but the alldatadiy flow chart thing i was following said to test the circuit 325 which is the wire from the pcm to the starter relay. But it said to test the resistance to ground & if it is more than 5ohms to fix the circuit & test for normal operation. The dvom im using just shows 600, 6000, 60k, 600k, 60m, when i tested it at anything less than 60k it would just show 0L or 0.L depending on where the setting is set. which is also what it shows if i dont touch the leads to anything? Before i ran a new wire with the meter set at 60k it was reading smthen like 13.4 but anything under 60k it would just show 0.L? Then after i ran a new wire it shows 0.L on all the settings? So i think there was possibly smthen wrong with that circuit but i still have no crank no communication. My thought was that possibly that wire might have fried the pcm? Now that the wire shows less than 5ohms i can move to the next step in the flow chart but it basically says after checking the trigger wire to the starter to replace the starter solenoid & test for normal operation but the starter is new & good i can get it to crank by jumping the starter relay but truck still doesnt start? So i never even tested that wire but i probably should just to be sure. The next problem is that the next step goes on to have me start testing the clutch pedal position switch which i dont think this truck has since its an automatic?
OL means you are out of range. When the leads are just laying there not touching, the resistance would be infinity. No meter can ready infinity, and you turn the meter to it's highest range 60M, the meter will still read OL because infinity is higher than 60M.

So when you are on a lower range, and try to read a circuit, and you get OL that means you are out of range again. So you keep turning the knob higher and higher up the ranges till you get a reading.
 

Aldo0280

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Just want to thank everyone for all the help! I actually got an ecm from flagship one & i used forscan to program the keys to work with the new ecm which right off the bat i was pretty sure the ecm was going to fix the problem because before i wasnt even able to communicate with the ecm with forscan or my snap on scanner. But after programming the keys it still didnt crank but i was pretty sure that was because of the wire i had ran directly to the ecm from the starter relay so i got rid of the wire i ran & reconnected the original wire & it fired right up! So it was the ecm after all! I have no idea what fried the original ecm but if anyone else runs into a no crank no communication at least in my case a reman ecm from flagship one & programming the patts keys with forscan fixed it! Thanks again!
 

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