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Transmission trouble for a 1996 Chevy 6.5 ltr turbo 1 ton dually

1

1tondaully

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Pittsburgh,Texas
I need to know how to determine which transmission I have a allison or a 4L80E transmission. I have determined that two sensors need to be replaced from error codes PO753 and PO758 but I can't figure out whcih transmission I have in the truck. The truck has 306,000 miles and the transmission has never had any trouble.
 
1tondaully said:
I need to know how to determine which transmission I have a allison or a 4L80E transmission. I have determined that two sensors need to be replaced from error codes PO753 and PO758 but I can't figure out whcih transmission I have in the truck. The truck has 306,000 miles and the transmission has never had any trouble.
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You will have a 4L80E.
 
These are shift solenoid fault codes. You should check the connector on the side of the transmission for an oil leak causing connector issues. Also check grounds esp for the ECM at the trans dipstick bolt top of engine.
 
I pulled the connector on the side of the trans. & it's has a little trans. fluid in the connector & I've checked all the grounds all over the truck & engine no problems there, I've got another problem that has croped up now, when I cranked it up it went runaway the engine started to hit the rev. limitor & the td dump still kicking the codes.
 
pulled each one of the grounds & cleaned them before I got online & check the oms between the ground stap & cab or cab & chase or engine & cab or batteries & cab& chase, how else do you check them out you don't just look @ them isn't that correct & no your not being rude & I hope I'm not being rude w/ my answer
 
no problem I'm going backwards with this hole thing let me start from the start when I was driving down the road a couple of weeks ago I heard a pop sounded like a rock hit the under side of the truck & I came to a stop light & took off from the light I covered the car next to me w/ black exhaust & you couldn't even see the car next to me & the truck started to run like a bat out of heck, didn't kick no codes @ that time, checked my turbo & it's fine, changed my IAT intake air temperature sensor, then after that I couldn't keep my speed regulated & if you put on cruise it both on & off it bucks like a bronco & cannot keep the speed regulated & then it started to kick the codes of po753 & po758 the electrical shift solenoids A & B, & now the truck when I started it friday morning it went runaway hitting the rev. limitor & the td dump, started it this morning & the engine started to idle real rough & sounds like it was injection was to close or the timing on the ijection pump was off but no white smoke out the exhaust, pulled the trans. pan & the fluid was alittle dark but not bad hasd no deposits in the bottom of the pan I'm stumped.
 
You are looking at a symptom as if it is a problem, or you have 2 seperate problems.

I dont care if there is a tranny in the truck or not, the engine should not run away. It also should not smoke or idle rough.

You know you have fluid in the connector so clean it then leave the tranny alone.
I know you are already there and want to change both solenoids, but shift 1-2 and shift 2-3 solenoids Bad at the same time out of no where and happen at the same time as engine problem? No too much coincedence. I am not a tranny guy, anyone have experience to say I am wrong, please do. A couple of new solenoids is a chance for a defective new to confuse the situation in my eyes.


Fix the engine problem first. If the ip or pmd is going screwy the varying engine speeds could be telling the tranny to do the wrong thing at the wrong time.
Rule #1 when anything screwy is going on clean the grounds and put in your test pmd. The "POP" is the only thing that has me wondering about the internals of the ip loosing governing control.
 
Oil is an insulator. So finding the 'leak' at the trans connector means you clean the oil off it (the pin connections) and will have to do so from time to time until you rebuild the transmission and that leak gets fixed.
You dropped the pan before or after the trans codes appeared?

Engine runaway is most likely a bad PMD - a few models were known to do this. There is a ground for the PMD on top of the IP. I recommend you replace the PMD and see if the one you have is a known bad one. The bumper relocate with an USA made cable is the best. leroydiesel.com
 
Gentalmen, I put everything back together & found a couple of wires that wasn't looking right under the intake, started to pull the intake & found some intake leaks, fixed the leaks & fixed the wires, put it back together & put the PMD on & fixed the rough idle, but I still have a problem w/ it not coming back to an idle after you accelerate it alittle bit it still wants to climb in acceleration, it will come back down slowly, still have a bunch of black exhaust @ acceleration. Drove big black & the shifting is real fast from first gear to fifth gear, from a stop 0 miles to 40 to 45 miles first to fifth gear, & still can't set my speed @ all, it still wants to take off it runs like a bat out of hell w/ a hole lot of black exhaust. it kick some codes will not no until tuesday evening will let you all know what they are as soon as I find out, can't rap my head around it, I'm wondering if it's my APP or if it's the govenor in the trans. or IP please help I need big black up & running thank you for any help
 
Gentelmen I've put a different PMD that I got from the place I bought my IP from about 204,000 miles ago, the code it kicked this time was P1656 Wastegate Solenoid Control Circuit, I fired up Big Black after I pulled the codes & it went back to running rough & it souds like the injection is to close it's stumbling.

Gentelmen, Do I need to start posting in the engine discussion area or not I need Big Black up & running so my wife can get the car back I'm sorry Gentelmen I need big black back THANK YOU
 
Gentelmen, I'll do it wendsday evening bad storm here in Pittsburg, Texas, I've got the one that came on the IP, thank you very much I'll let you know what happens tomorrow Thank You
 
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