l_kusler

So i'm into some troubles with my 6.0l swap. Finally got it all in and reconnected last night. Starts right up after about 20revs. Seems to idle down normally, but immediately i'm in Reduced Engine Power. Check it with the a handheld. Only code i read is P1518. I have no throttle actuation. I shut down and and recheck my ground points, reclean and reinstall. Still does the same, Check harness to tb, and tac module, everything looks good and clean. Verified connections and refired. No change. I try to reset the code and now the programmer won't connect. try to restore tune, same thing, at one point it even said unrecognized vin. i am down to 12.2v not too low to communicate? Also now i have lost cranking ability with the no communication, it won't try to turn over, no solenoid click. Is the PCM fried? Or is there something i'm missing? I will throw it on the charger for a bit and see if that makes a difference.. Thing is the only change i made before this complete loss was playin on the handheld. Any help is greatly appreciated. I don't have HP tuners or anything to really log, as i was planning on taking it up my college and dyno tune it there in the following weeks as they have hp..

1_fastsilverado

iTrader: (2)

Just from what it sounds like, I'm guessing you have a handheld for tuning? You would need to get a 6.0 base tune flashed onto the ecu and then use hptuners to tweak it from there. Basically until you get a different base in it, it's not going to run right.

l_kusler

Thanks for the reply 1 fast.
I understand i need to change my tune over. I'm just concerned in the meantime why it fired up and idled fine aside from the dbw issue forcing it into REP, but it still should run, as it did. Now doesn't even turn over and pcm doesn't seem to respond. On run position cluster lights up, fuel pump pressures up, and throttle reacts and then moves again after one second. (indicating no response from pcm?!) Another thing i noticed was i don't have a gear selected according to the cluster. More and more **** seems to be going haywire, sometimes airbag lights sometimes security lights, service brakes, etc are lighting up on the cluster... Yet nothing is shown on the information center other than low washer level, no more REP as it was initially. So the bcm is talking but no pcm? If i am having no luck communicating with the pcm via the handheld is there a chance hp tuners will have better sucess? Can it force write or erase a pcm? Will i have to buy a couple credits to use hp and then find out i need to buy more cause this pcm is shot if thats the case? This is frustrating me, too many variables, too many questions. I am getting a manual through alldata see if i can follow the troubleshooting steps into the problem. If anyone has any other ideas or things to try i'd be very happy to hear!

white lightning SS

iTrader: (3)

Recheck the ground at the back of the RH head. (wire breaks off) Make sure you have the ground strap installed fron the LH head to the body. Then check the ground on the LH lower frame. You have a ground problem for sure. I see this about once a month at the dealer. There should be 2 grounds at the back of the RH head or bolted to the top of the block in the rear.

GMCtrk

iTrader: (27)

I guarantee you that you have a bad ground. Same problem (not same symptoms) I had after the 6.0 swap. Ended up being a loose ground, the big one that goes from the battery to the front of the block.

white lightning SS

iTrader: (3)

Oops forgot about the main one!!! check that too especially if you painted the block!!

l_kusler

Hey guys, thanks for the replys, but still not running

LH Frame ground.. can you explain a little more on this lightning? Im not sure if i had this one off to remember it..

I had thought about the ground issue right off the bat, almost was positive that was my problem. I had buffed all my ground points clean to bare metal before the install. However i did relook over and check; i had forget to hook up the tranny harness ground wire to the block.. I did this and still no luck. I have 3 grounds on the back of the motor. (firewall to motor, injector harness to motor, and tranny harness to motor) I have the large side block ground with another harness ground on, and the front rad support ground aswell. Others? I did the security re-learn procedure thinking it was locking me out, no luck. i swapped the pcm from an 06 over to mine and it acts differently. I have cranking with the new pcm but no fuel. The throttle responds to the pedal. i also have connectivity for codes with the scan tool on this pcm. this leads me to believe mine is fu*ked. I hauled it up to my college today, and will have hptuners to see if i can connect and find out anything else. It ran for 15 mins probably before all this crap went down, then i try to restart and nothin, i musta got a shock or surge i guess, feeling pretty pessimistic bout it right now.

viciousknid

iTrader: (8)

After you hooked up the other ground did you unhook the battery for 30 seconds to attempt to reset the codes.
Also, check your fuse box under the hood to see if you blew a fuse for the cig lighter. that could cause you to not be getting a response on your handheld.

viciousknid

iTrader: (8)

Here's some good info from LS1Tech.
https://ls1tech.com/forums/pcm-diagn...1518-help.html

white lightning SS

iTrader: (3)

The LH frt ground is under the radiator support on the LH frame rail. Check to see if the LH low beam is dim this a good way to check that. Although if you could communicate with another pcm and not yours that possibly is it. Keep posted.