Need help with my 4l60e
Need help with my 4l60e Hey guys long time since i have posted,so i bought a 2001 gmc sierra 1500 5.3l 2wd 200k miles.the tranny was stuck in third gear.scan for codes and the 3-2 downshift came up.replaced all shift soleniods,new fuild exc.when you start up the truck and drive off it will shift from 1-2 then 2-3 and stay stuck on third gear.never hits overdrive or come back down to first.the only code i have now is p0785 i believe.read on couple forums it can be my ignition switch or my pcm?need all the help i can get thanks.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
i have also read it can be the ignition switch.now dumb question can the neutral safety switch on the transmission have an effect on the problem?since its adjustable?
i hate swapping parts and hoping it fixes the problem,a remand ecm 120 dollars,factory ignition switch 130 dollars,nuetral safety switch 55 dollars.so i hope some one can help in fixing my problem
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Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
I agree in hating to throw parts at a problem, but a certain point, there's nothing else you can do. You have all the information on hand as to what causes this problem. There's not much more to be said.
You've tried the basics (solenoids) and it hasn't worked. I'd follow the example of the guy who did everything you did, then swapped the ECM, and solved his problem.
You've tried the basics (solenoids) and it hasn't worked. I'd follow the example of the guy who did everything you did, then swapped the ECM, and solved his problem.
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Verdad Gallardo alldata was a procedure/test to check if i have correct voltage/ground at the transmission plug.i will check it over next weekend and post results.basically no power bad ignition switch,no ground bad ecm
found my problem.the wires going to the main tranny harness basically broke off from the leads on the plug.i had four broken,so i went to the junk yard found a Healthy plug from a 2001 astro van, so i weld and heat shrink the harnees and problem sloved.all my gears work but the truck slips for like a second between shifts what can that be?????????????
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Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Slippage could be due to low line pressure or excessive wear.
Low line pressure can be due to:
Low fluid level
Defective EPC Solenoid
PCM tuning issues
Engine sensor problems (TPS, MAF, MAP)
Worn pump
Significantly worn valve body
You could start by replacing the EPC since a bad one can be difficult to diagnose. Hook up a pressure gauge to the trans and note the line pressure when the shifts take place.
Low line pressure can be due to:
Low fluid level
Defective EPC Solenoid
PCM tuning issues
Engine sensor problems (TPS, MAF, MAP)
Worn pump
Significantly worn valve body
You could start by replacing the EPC since a bad one can be difficult to diagnose. Hook up a pressure gauge to the trans and note the line pressure when the shifts take place.
