4l60e gone nuts

[mr3825bill]

I have a 1998 z-71 and the other day the tcc was jumping in and out. I turned around and it kept doing it. I got to a stop light and it didn't want to shift. The motor sounded like it was running out of gas and had no power. Pulled over and checked everything and all looked good. Trans is about a year old and the fluid was clean and smelt good. Put it in reverse and nothing happend it just revved up. shut truck off and restarted and reverse worked. shifted good till next light and was in limp mode. It started slipping really bad and barely made it home. Shut it off and imidiatly restarted and it went and gear and shifted no slipping. I can drive it for a few miles before it starts slipping but all I have to do is shut it off and restart and it shifts again. No codes are setting. I grounded the solenoids to check them and the 1-2 one doesn't seem as loud but was clicking. My scanner only reads upto 1997. It shows both solenoids as off all the time when it is working properly but reads 3-4 as on all the time when it is slipping. I grounded the wires at the plug and can make it shift all gears untill around a couple miles then it starts slipping again even then. Unless I shut the truck off and resart it. Something is resetting but I have no idea what. I cleaned all grounds. Cleaned wires at vcm and trans. unplugged connector on pass. side and it went to limp mode and shifted.

[transman618]

Well, a couple of things I noticed about your post is first, your scanner readings dont sound right. You said that when the trans is operating right both shift solenoids read off. If both read off then you should be in 3rd gear all the time. Another thing is reverse is not electronically controlled. If you are having problems in reverse then you are looking at an internal problem. What kind of scanner are you using?? Will this scanner tell you the functioning of the TCC solenoid??. I'm really leaning towards an internal problem like the pump or the torque converter. Was this rebuilt last year??? Can you take it back to the builder??


transman

[mr3825bill]

It's an older cornwell scanner for obd1 but sorta works on obd2 thats why I'm getting the funny readings. I'm trying to find the paperwork to take it back. That really boggles my mind why reverse works good enough to break the tires loose then it goes to limp mode and no reverse I shut the truck off and imedially restart and reverse works again.

[777stickman]

You may want to do some electrical checking also.

The ign switch has 5 contacts in it. One of these is dedicated to powering the TRANS fuse #20 10a in the IP fuse panel. There should be power on both sides of this fuse when the key is in the Off, Run and Start position. Power from the fuse goes direct to the tranny solenoids (Pink wire). The grounds for each solenoid are controlled by the VCM.

Also is the shift indicator light acting up when this happens?

[mr3825bill]

I checked and the fuse has power on both sides all the time except when the key is off. I pulled the fuse out and looked at it it looked good so I put it back in and decided to drive around and check again when it acted up. I made several laps around the block which should have been more than enough but it shifted perfect every time except once with only a slight flare going into third. Now it seems to be ok. Will see what it does on my way to work in the morning. The indicator light stays on as far as i know but will double check that too. A friend at work bought a trans for his tahoe when he thought his was going out but he got a 4L80E instead of a 4L60E. Wants to sell it to me for 200.00. Only problem is its for a 2wd truck.

[mr3825bill]

Well it shifted great all the way to work. Unfortuantly not on the way home. Started slipping really bad in all gears. I could turn off ignition and start it back up but it would start slipping again within a minute. I unplugged connector at trans to see if it would slip in fail safe and it does. I guess I'll limp it to a trans shop in the morning and start shopping for a manual trans. to replace it with if it goes again. To make matters worse I was going to drive my 86 gmc to work while this one is down and while finishing wiring the msd I snapped off the dipstick tube with my foot on my new 383 stroker i just built and its stuck in the block and can't for the life of me get it out. When it rains it pours. Thanks for all yalls help though.

[Jacobpettiet]

I’ve been searching the web for this same exact problem and a solution. I know it’s been 12 years but do you remember how to fix this?

[Schurkey]

Originally Posted by Jacobpettiet

I’ve been searching the web for this same exact problem and a solution. I know it’s been 12 years but do you remember how to fix this?

Wild Guess: Excess debris in the pan from a failing transmission. Debris gets sucked into the filter, plugging it. Trans slips because pump is starving for fluid.

Shut engine off, some slight back-flow in the filter dislodges some debris. Pump can pull fluid through the partially-plugged filter until it sucks more debris into the filter which fully plugs the media. Pump starves for fluid, trans slips.

At best, you could change the filter, clean the pan, flush the fluid and hope for the best. At worst--and more likely--it's time to overhaul the transmission.

When my 700R-4 in my '88 K1500 did that, I found pieces of the 2--4 band laying in the pan, and disassembly revealed that the planetary gears had broken teeth.

[Blue Bowtie]

Broken? That's only a few teeth, just a nuisance.

THAT is broken.