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Tim's Auto Repair
Tim's Auto Repair, Mechanic
Category: Transmissions
Satisfied Customers: 15773
Experience:  I have been rebuilding automatic transmissions for 25 years
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I have a 1994 gmc 3500 diesel with a 4l80e trans wont shift

Customer Question

I have a 1994 gmc 3500 diesel with a 4l80e trans wont shift when hot some tims when cold
Submitted: 8 months ago.
Category: Transmissions
Expert:  Kevin Bourcier replied 8 months ago.

hello I can try to assist you with this .

Customer: replied 8 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Provide Diagrams, Manuals, or Instructions. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Tim's Auto Repair replied 8 months ago.

Hi, My name is ***** ***** for the delay.

I will do my best to assist you.

does the speedometer always work?

Expert:  Tim's Auto Repair replied 8 months ago.

when you say it wont shift,what do you mean?

Customer: replied 8 months ago.
the speedo works I relaced the speed sensor and two updated speed solinois still same problem oil is clean
Expert:  Tim's Auto Repair replied 8 months ago.

what solenoids did you replace?

Customer: replied 8 months ago.
I replaced the two shitt solinoids 12 and 34 shift solinoids
Expert:  Tim's Auto Repair replied 8 months ago.

12 and 34??.

Expert:  Tim's Auto Repair replied 8 months ago.

in the picture,,what all did you replace?

Customer: replied 8 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Tim's Auto Repair replied 8 months ago.

are you there?

Customer: replied 8 months ago.
I should have explaned its 1and 2 shft solenoid and 2 and 3 solenoid
Expert:  Tim's Auto Repair replied 8 months ago.

ok

tell me,does the engine light stay on?if so,can you give me the computer codes?

Customer: replied 8 months ago.
it has a code 34
Expert:  Tim's Auto Repair replied 8 months ago.

ok

sense you have already replaced the 1-2 and the 2-3 shift solenoids and from the way you explain..

i would think your problem here is the tfp switch[transmission fluid pressure],,this is the flat pressure switch that is mounted to your valve body.#40 in the picture i gave you

the code you have is for the injection pump timing,the timing may be off a little

PLEASE COPY AND PASTE the link below to your browser, I have uploaded more info on this there please copy and paste the link below to your main browser[INTERNET EXPLORER or FIREFOX]

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https://www.dropbox.com/s/njvj37ge9nbt4e8/0817-gmc-This%20article%20was%20updated%20by%20TSB%20No.doc?dl=0

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if the link doesn’t work that way, try it this way

thanks

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www.dropbox.com/s/njvj37ge9nbt4e8/0817-gmc-This%20article%20was%20updated%20by%20TSB%20No.doc?dl=0

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If you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feed back ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more help