4l80e transmission ??

[DRodgers]

Hi all,

My truck has started to give a trans problem. When I start it and put into D or R its like its in neutral. You can,t move in either direction. Now if I shut down in park and restart everything works fine. This may happen at any time. Some times it goes for weeks and never happens.
I thought I read that this could be the ignition switch, but have not been able to find this when searching you forms.
Went to the dealer to price a switch, big bucks $320 , too much to trouble shoot with and also time consuming to install.
The truck pulls 6 ton trailers with no slippage or shift problems so I don't think the trans is going.
So any ideas?

Thanks,
Dale

[mafrazer1]

Sounds like your "service throttle soon" lamp is out.
Shutting down and restarting resets the DTC.
Go to autozone and have the codes read.
The TPM (throttle position module) has 3 circuits, when 2 are lost you go to some sort of limp mode, which in my case was total transmission disconnect. Engine runs, but no go.

My suburban showed the same symptoms when the electronic throttle was acting up.
I replaced it and have had no trouble since. I knew it was a throttle problem 'cause I had a working bulb in the "service throttle soon" position.
Check your bulbs, and look for a replacement throttle/pedal assembly.
The local chevy dealer wanted $550 to "fix" this.

Good Luck!

[DRodgers]

Thanks for your reply. My service throttle light is working during self-test at key on and I have a code scanner which shows no current codes.

What is your opinion about other possible causes?

Thanks

Dale

[rustyk]

This is a WAG, but I had a similar issue on a different transmission; the problem was the tranny filter was plugged. Apparently, when the engine was started, and shifted into gear, it would suck some fluid into the intake, but not enough to engage. Shut it down, wait a couple of minutes, and all seemed fine. It finally crapped; I had it towed home, changed the fluid and filter, and never another problem.

Hopefully yours is that simple.

[Robyn]

Get the tranny serviced and have the tech replace the A and B solenoid as well as the O rings on the solenoid feed circuits. ( there is a tech bulletin out on this issue)

There are some O rings in the feed circuits that get hard and flatten out and then they wont allow oil pressure to build to the solenoids and then it won't go.

This issue is usually most prevalent when the tranny is hot. A cold rig will usually work fine. Once the thing goes into gear all is well. ( with the oil cold the leaky O rings will hold enough pressure with the thicker oil)

It wont show any codes as it is a hydraulic issue rather than an electrical one.

With the pan off you can also see if there is any excessive amounts of crap in the pan too. A fesh filter and some new oil are a good thing also.

My 95 just went through this issue and I got ahold of all the tech Bulletins and this is what it turned out to be.

The solenoids are about $39 for the pair and the O rings are a couple bucks. The cost was a total of $200 with the filter and oil change too.

I had a friend do it as he wanted to do some trading on a gun deal at my shop. He fixed my tranny and we made a trade. Hmmmmmm :D

Things do work well once in a while and we are both happy.

best
Robyn

[DRodgers]

Just to update you all, as of now my problem has gone away. The truck has worked without further issues. The truck did have the trans serviced last May with the pan off and filter and oil replaced. There was very little stuff on the magnet or in the filter. I have done this service every spring since buying this truck in 1999.
I'll let you know if it happens again.

Thanks you for your replies and suggestions.

Dale