• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

95 6.5 t.d. 4l80E no upshift

M

moosehunt

New Member
Messages
2
Reaction score
0
Location
Palmer Alaska
1995 6.5 t.d. 4x4 4l80E tranny has no upshift. Checked fuses and grounds, replaced 2-3 shift solenoid, changed filter and oil still no upshift. Must be in second gear, it cruises at about 30m.p.h. at 3,000 rpm. When I let up on the pedal it feels like there is no engine brake, just kinda rolls smoothly to a stop. Had the codes pulled today and got DTC 78, 81,82,83....The guy who pulled the codes said I should look into a new ignition switch. Any ideas on why all the tranny DTC codes???
 
first off, welcome to the truck stop

your right about it being in 2nd gear. that's the default gear.

code 78 don't know that one

81 Shift Solenoid B Circuit Error

82 Shift Solenoid A Circuit Error

83 TCC Solenoid Circuit Error.

I'm wondering if the 78 is actually a 75(System Voltage Low) given the suggested IGN replacement.

double check your grounds, they like to be spotless.

http://www.thetruckstop.us/forum/showthread.php?14596-6-5-grounds.

other than the transmission problem has the truck been good(engine wise) or are you having other issues?

 
I love this Truck!! so does the wife....if I could find out why the tranny isnt shiftin I know I could getvmany more years outta it...Thanks for the welcome, I will pull it into the garage after church and double check the rounds
 
How does the main electrical plug to the trans look driver side rear? oil covered? Clean it and check for pins pushed back.

Positive cables also can fail esp the wire coming off the driver side positive going to the alt and the other one to the main bus.
 
I have the same codes of errors out instead of 78 have the code 73. These codes can be caused by lack of grounding or 12 volt ignition? My truck are thaoe 1995 with 4l80e transmission.
 
4l80Ewiring.jpg
moosehunt said:
1995 6.5 t.d. 4x4 4l80E tranny has no upshift. Checked fuses and grounds, replaced 2-3 shift solenoid, changed filter and oil still no upshift. Must be in second gear, it cruises at about 30m.p.h. at 3,000 rpm. When I let up on the pedal it feels like there is no engine brake, just kinda rolls smoothly to a stop. Had the codes pulled today and got DTC 78, 81,82,83....The guy who pulled the codes said I should look into a new ignition switch. Any ideas on why all the tranny DTC codes???
Click to expand...

Hi Moosehunt, and welcome.

DTC 78 is wastegate solenoid fault. sets when RPM is higher than 1800, fuel rate greater then 20mm, boost pressure greater then or less then desired(internal to PCM)

Could be you boost sloenoid is defect, checked vacuum lines ??

The other codes seems like you dont have power to the transmission, It usual defaults to 2nd then.
Look at the picture of the connector, and meeasure for ign. voltage at pin E.

You can measure ressistance of the A, B, tcc solenoids to
A sol = Pin A to C 20 to 30 ohms
B sol = Pin B to C 20 to 30 ohms
TC sol = J to K 9 to 11 ohms

The solenoids still can have a mecanical fault even it they measure ok, i just experiensed that.
 
You must log in or register to reply here.
Back
Top