jeffhulsey16

Its a 2003 GMC with a 4.8 and a 4l60e. New rebuilt transmission and i still dont have first gear. Has new elecrtonic throttle control (200) trans guy said he thought it was like a kickdown cable...and it wanst. It has a new computer (200) trans guy thought the comp was messed up. Ive been driving this truck for the last 6 months without first in it and the trans guy is just now getting around to rebuilding me another trans.

buzzkillwill

iTrader: (5)

Not sure exactly what you're asking, but I think your truck is equipped with a drve-by-wire throttle body, which means it's controlled by a sensor, no wire or cable. I think it's on the 03's(?).
As for the TCM, I don't know if you have one, but I believe the tranny is controlled by the PCM. I know some of the new GMC's have a TCM, but I don't know what year they started. I know my 04 Chevy uses the PCM to control that transmission.
So any adjustments for the tranny would be made through that.

Kinda odd that you don't have first gear... Have you taken into the dealer, or do you know anyone with programming software that can check for you? Does the truck run fine, otherwise? Not sure if it's in limp mode, or something....
I know the tranny won't last long taking off in second all the time.

jeffhulsey16

Yeah, it is a drive by wire system. When I went to the salvage yard to get a new pcm (it was $55 bucks and it was out of a truck that had wrecked on the test drive so less than 1 mile on it) the guy asked me which computer i wanted(so i figure there is more than one therefore possibly tcm?), and i dont know any better so i just said pcm, i had to take it to the dealer to get the pcm installed, and i didnt want to mess with all the bull, but they never said anything about the transmission. The trans guy also checked the sylinoids and said they were good

It idles and revs perfect. I had cut the cats out so it reads a o2 sensor code, but from everything i have read this wouldnt cause me to loose 1st. Also it has a late 3-4 shift, but it goes away...kinda. The transmission guy has a brand new snap on hand held computer and said his assisstant drove the truck and he said it goes into first but shifts at 1000 rpms? Either way, pcm or trans im sick of this truck, i want to sell it for 9000 and buy me a CHEAP as$ 4.3 and throw in a ls engine. i appreciate your help and any info weather right or wrong is still welcome!

viciousknid

iTrader: (8)

The TCM is part of the PCM. The PCM controls the Engine and Transmission both.
Did you just all the sudden lose it one day?
any difference between the day it worked and the day it didn't?

jeffhulsey16

lol i wouldnt know haha. my truck has been f' up for quite some time now. old trans started slipping when cruise was on and i was going uphill ( it would downshift and rpms would go sky high but never catch a gear) and was running poorly so i got a rebuilt one. trans guy said there was a check ball stuck in the plate. still didnt run right so i took it to chev garage and they said cats were clogged causing missfire, so i cut the cats. It had 1st when i pulled the old slipping trans, but i didnt have clogged cats (missfire)when i drove it. now it has no cats and no missfire and a rebuilt trans and no first. so anyone know what the salvage guy was talking about when he said other computer? its a chevy only salvage, so their pretty knowledgeable. helk if i know

viciousknid

iTrader: (8)

The only other computer I know if is the BCM which doesn't effect the trans as far as i Know. When you put the new pcm in the dealer had to reflash it with your trucks information and that allowed it to communicate to your bcm.
Can you manually hold 1st gear?

jeffhulsey16

nope nothing...acts like its in second

budhayes3

iTrader: (19)

If it was in limp mode you would be starting out in 3rd...as for onboard computers there are a few, the PCM, BCM, SRS (Supplemental Restraint System, aka- airbag), ABS Module, but the 2 main ones that are usually referred to are the PCM (Powertrain Control Module) and BCM (Body Control Module). As viciousknid mentioned, the transmission is electronically controlled by the PCM. If you had first gear before the trans rebuild and now you don't, I'd have to think that the trans builder messed up and the trans probably needs to be pulled and gone through again.

jeffhulsey16

Lol, yeah...thats what i had thought, but the guy claims that he stands behind his transmissions, so he is going to build another one and install it and if it fixes it then it was his transmission and not my truck, but if it doesnt then i dont know wtf to do. He has 5 vehicles in his shop right now that need fixed, and he said that because mine drives as soon as he gets done with those 5 he will jump to mine. He took my truck to a electrical shop to check it out and all they could tell was that it was either the pcm or the trans. Its been 3 weeks since ive had my pcm installed and he still hasnt fixed my trans. not to mention the other 400 bucks i've dished out (200 for the DBW TPS that read 20% throttle when the truck was turned off)(200 for reprogramed other pcm) I cant remember if i paid 600 or 700 for the trans(6 month warranty), then i paid my buddies to install it. either way my bung hole hurts cuz i feel like i've been raped. the 6 month warranty went out a few weeks ago, but I told him that the trans wasnt working right a long time ago, do you think that he is trying to get out of it?

andrew383

iTrader: (14)

the trans has got to be messed up,if it doesnt get fixed this time give vince a call at FLT and see what he can do for a stock rebuild