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4L60E aggravation

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phantom 309
New User

Oct 12, 2021, 12:19 PM

Post #1 of 6 (228 views)
4L60E aggravation Sign In

Hello all first post here, hope i don't muck it up.
!997 chevy cheyenne 305 auto. C2500

I coded a P0785 went into limp,. i changed out both A+B solenoids,. drove it for 2 mins and all 4 plus lockup just fine.It coded P0785 again. couldn't clear the code. I dropped the pan inspected every bit of wiring, new filter and fluid ( nice color very little clutch material in pan) and changed the pressure manifold.Started it no, cel drove for 2 mins all 4 plus lockup,...then it recoded P0785.Frustrated i let it sit for a day,. started it, drove 2 mins again with no cel and same symptoms again,.So researched as much as i can, wading through 4L60E drivel is mind numbing,.My VCM
I came up with possible poor ground for the VCM, (usually referred to as ECM) it gives a fix for adding another ground path by switching wires and pins and adding a jumper wire. The number of the vcm in question is different than mine,
My VCM has service # 16229684,. no mention of this vcm so i,m wondering if i need to do this or if anyone here has experience with this,.
I,m just a shadetree guy laying on my back in the driveway, swearing at GM for putting the cross member just 2" across the back of the trans pan,...So expert advice would be very welcome.Thankyou its daughter truck so my stress level is higher,.

(This post was edited by phantom 309 on Oct 12, 2021, 12:21 PM)

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 12, 2021, 1:57 PM

Post #2 of 6 (220 views)
Re: 4L60E aggravation Sign In

Our resident trans expert (gsferraro) will be along when he has time. He owns a trans shop and is very busy.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.


Oct 15, 2021, 5:45 PM

Post #3 of 6 (125 views)
Re: 4L60E aggravation Sign In

Po785 is the 3-2 down shift solenoid, did you ohm out the solenoid? It's not the manifold switch. Gary

phantom 309
New User

Oct 19, 2021, 9:30 AM

Post #4 of 6 (58 views)
Re: 4L60E aggravation Sign In

I have been away on a project and haven't looked at this yet, BUT,... i bought a small innova code reader. I read what it told me,. P0785 solenoid "A" but after gary told me that P0785 is 3-2 shift solenoid, i realised that i had wrong info,. needless to say i will swap out the 3-2 solenoid and see how we do.
Daughter drove it 5 miles or so yesterday with no troubles,.till it got warm
i am also looking to get the code read bu another code reader to see if it really is P0785, or its something else, which translated through chinese technology ends up show P0785 on the screen. aargh.
Thankyou gary, i will update this either when its fixed or we swap the 502-4l80e combo in there.


Oct 19, 2021, 5:54 PM

Post #5 of 6 (39 views)
Re: 4L60E aggravation Sign In

Ok, sounds good, Think shift solenoid A may be P0750 code. Let me know how it goes. Gary

phantom 309
New User

Oct 19, 2021, 5:55 PM

Post #6 of 6 (39 views)
Re: 4L60E aggravation Sign In

SUCCESS!!! Thankyou Gary for the help. I changed the 3-2 solenoid and we drove it for half an hour,. and things are going just fine,. So,. just the lockup solenoid and pwm solenoid to go,.. by then the 3-4 clutches will be worn out,. 4L60E such fun.

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