the pcm grounds ohm good with key off but when with key on they get high resistance anybody know the cause of this.
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the pcm grounds ohm good with key off but when with key on they get high resistance anybody know the cause of this.
You aren't supposed to test resistance on an energized circuit. That's where a voltage drop test comes into play. Resistance is like a static test for an unenergized circuit, a voltage drop test is like a dynamic live circuit test.
Using Ohm's law, you can determine resistance between two points in a live circuit when using the voltage drop test.
What type of issues are you having? IMO while ohm checks have their place, once you energize(complete) a circuit, you have introduced current flow into that circuit.
There are cases where a wire may test perfect during an Ohm test(0 Ohms) but when energized, may allow a huge voltage drop due to(for example) having only one strand still intact. In this case a resistance check would yeild perfect specs, but a voltage drop test would nail it.
Ohm out the wires end to end but not through an entire energized circuit.
The truck isn't cranking I think I have the trans signal hooked up wrong but I was testing grounds on the pcm to ensure that wasn't it and was worried that a power wire was shorted when i found the high resistance with key on. And on the pcm c1 39 black and yellow wire should be the ground at crank to the starter relay right, because there is 9.86 volts here when in crank.
So is it not cranking or not starting?
wont crank with key but will when i jump the starter at the relay
How did you wire the starter?
Similar to the 03 only deference is I used the I/P crank fuse insead of the Under hood fuse. on the PNP switch i used the wire g the park neutral signal to the one side of the coil of the relay and the yellow and black from pcm c1 39 on the other side of the coil to be the ground.
Got me confused. Why didn't you run the original purple starter wire straight to the starter?
i did
Sorry man im lost. Was your obs not an auto truck with a p/n switch on the column. Don't understand why you used a seperate relay. Also what is the function C1 39?
Obviously the pcm is not able to pull that pin low enough to energize the relay since your meter reads partial system voltage during a crank attempt. If I understood what you are doing, maybe I could help.
It was an auto and i'm using the stock relay just rewired it to be like the 03 and c1 39 is starter relay control according to the wiring diagram it is supplys ground to the starer relay.
So i noticed that i have 10 volts on the case of the pcm with key on
Hmmmm. Never tried it that way. I literally run the stock purple starter wire from the ign switch straight to the starter, nothing else.Quote:
Originally Posted by wayoung
Wow... I think you have made a fundamental mistake somewhere. Do a voltage drop test on your ground leads at the battery. You should have a lead going to the engine block, body, and frame. The pcm board doesn't groung to the case. I assume you have the case mounted in a way that grounds it? That's ok, but that sounds like you don't have a good ground to the body or whatever you have the pcm mounted to. This is weird...Quote:
Originally Posted by wayoung
Wow, if your case is energized with 10v when the key is on you have something seriously wrong in the wiring or the PCM is toast.
I'll check the pcm ground with a voltage drop test tomorrow,pcm isn't mount still need to send it off for tune, just wanted to make sure wiring was right first and i hope the pcm isnt fried.
So I pulled the comp off the harness then checked voltage at each pin on the harness and found 10.6V on all my grounds and the OIl level signal, and 9.6V on the VSS signal. So I guess I'll have to go through the harness now for a short.
Follow your harness and see if you pinched it anywhere, like the cam position sensor wiring between the transmission bell housing and the block. It's easier to do that you think.
wow this sucks i shake the harness at back of block and it goes between 0V and 12V at ground and then take the harness apart there, and can't find anything and wont go back to 0V.
Yay I think I got it one of my grounds wasn't grounded properly man i feel stupid three days of chasing wires
Ok missed a ground and spent a week trying to find it. But now its pretty much good to go waiting on the computer to come back from the tuner. And figured out why it wouldn't crank with key, the shifter cable wasn't going forward enough to register that it was in park unhooked cable push linkage forward and now it works.
I need a new shifter cable any ways are the obs cables suppose to work with out a problem.
the only reason why it wouldn't is if your shift selector arm is longer on the newer trans than the old one. If you still have the old trans, compare the shift arms and mounting brackets.
I still got it I'll take a look at that. Thank you.
Does any one know if the micro relay is strong enough to power the second electric fan with out burning up.
So the selector arms were a little different but even after swapping them I had to adjust the cable length.
Got the PCM back today and started it up, But I have a fuel leak at the new lines I used r6z4o6 idea seen here http://www.ls1truck.com/forums/238259-post16.html can anyone tell me the part numbers to go steel braided I found the part number for the fuel rail connector but cant find the adaptor to go from 6-an to M16-1.5 anyone know where to get it.
http://www.summitracing.com/parts/RUS-640830/ wow, 15 seconds to find. :laugh:
Yeah I spent three days searching for it with no luck
Thank you Red heart beat got my new fuel liine.