GM transmission, the 4L80 E unable to select 1, 3 or 4th..

[daveB110]

My 1994 30' Monterey by Cobra, with GM 454 running gear will sometimes not run in 1st, 3rd, or OD 4th. Only 2nd gear and reverse. This transmission has the electrical connection (4L80 E). Traveled from Louisiana via California home to BC since the last time, now find it doing the same thing. Any ideas?

[lawrosa]

You need to get the codes.. This is before OBD..

they went to the ODBII system in 96, use paperclip jump the A&B terminals, the diagnostic port is under dash drivers side the two terminals you need to jump will be the two most upper right, put paperclip in turn key to ON only get ready service engine will flash codes, will start with one flash pause two flashes means 12 everything is working, will do this 3 times then move on to next to code, will repeat 12 when it done.

Get the codes and post back..

A mechanic in Marbrorough, Mass. recomended checking the instrument array for problems.

U need to find new mechanic...Unless he means pulling codes...

Read here...( You may have grounding issue)

http://www.trutechtrans.com/Topic-1-00-01.html

[daveB110]

This is a new crate transmission from GM, as of last September, once installed, my problem was the exact same - the old transmission was still good! After much fiddling around, and unsucesful tryout drives with the brand new tranny installed, "something" changed and we got all the gears. After three more episodes during which we traveled several thousand miles, the problem has recurred. A mechanic in Marbrorough, Mass. recomended checking the instrument array for problems.

[okhmbldr]

I had the same transmission with the same symptoms. It was the shift solenoids. Easy fix, and do a transmission service at the same time. Lawrosa has it right, they are pretty cheap.

[RandACampin]

newman fulltimer wrote:
the biggest culprit with gm is the ignition switch

How does the ignition switch keep the transmission from shifting to all the gears?

[DougE]

Agree with lawrosa. Appears electronics are going into limp home mode due to mechanical problem. Time to bite the bullet and go for a rebuild.

[lawrosa]

daveB110 wrote:
My 1994 30' Monterey by Cobra, with GM 454 running gear will sometimes not run in 1st, 3rd, or OD 4th. Only 2nd gear and reverse. This transmission has the electrical connection (4L80 E). Traveled from Louisiana via California home to BC since the last time, now find it doing the same thing. Any ideas?

Change the trans fluid and filter. While its open change the two shift selonoids.. They are about $30 bucks a piece...

Your sysmptoms leans towards the selonoids. The trans is going into limp mode.

When mine went , 96 L460E, I hobbled to the trans shop in second gear..

My 96 was the first year of OBD codes and I threw a check engine light...

[newman_fulltime]

the biggest culprit with gm is the ignition switch

[azrving]

I would check all the electrical connections first. Unplug and plug them back in while looking for any corrosion. They should all be weather pack/deutsch connectors but failures happen. Also remove all the fuses and push in relays in the power center so as to establish fresh connections.

DO NOT use wire brushes on the face of the connectors as voltage may be inadvertently sent to other terminals. Look up Mexicowanderer posts for a good electrical cleaner that he has recommended.