4x4 4L80e trouble

[Yachtcare]

Regarding truck in sig below.

Tranny running rather hot. 210-230*(sensor in test port on driver side) Coolers run thru rad first, then auxiliary on front of cooling stack, then thru a cooler mounted under the cab with a fan on it. Stock pan and fluid correct on stick.

In past couple of days it has been running at the hotter temps, around 190-195* before that(stat temp) unit has about 250K miles, AFAIK. Seems I've lost 3rd and OD. (Running about 3000 rpm at 45-50 mph, with 4.10 gears). No SES codes.

While I'd love to just replace with a fresh unit, $$ a bit tight now. Any ideas on trouble shooting would be appreciated. Need to get a few more months of life out of it.

 

[Turbine Doc]

how clean is rad/cooling stack, heat is cumulative, drop pan, check it out fresh fluid & filter should not be that expensive and will give you better look at what is going on in the trans to see if mechanical issues are present.

 

[great white]

No third or OD sure sounds like "limp mode".

The is usually accompanied by a code though.

When you say "no codes", have you checked with a scanner or are you just going on the no SES light?

A stored code can put the transmission into limp mode and it has to be cleared before the transmission will shift properly again....

 

[Yachtcare]

TD, cooling stack cleaned in late July in my usual annual maintenance routine.That is...rad pulled cleaned inside and out, system flushed, condenser, oil and steering coolers cleaned til I can see light thru them. Could fan clutch be an issue here? It's only about two years old, no signs of leakage, but everything seems to be of questionable quality these days.

GW, No SES light, and no stored codes, but for good measure, I will disconnect the neg cable for a half hour today to clear anything that might be hiding.

This morning, (nice and cool) it took about eight miles to get up to 210*,(with the fan on) ambient temps low 70's. Detecting a bit of a shudder on acceleration from a stop, also.

A local guy tells me 210* is kinda normal for a 4L80e. But I had 700r4 behind a 6.2 with a a/c condensor as a cooler that never got above 125 while towing in OD, so 210 and upwards is concerning to me. Especially since the ambients are lower now than they were a few weeks back.

 

[WarWagon]

How does the fluid look and smell?

210-220 is normal as 4L80E's can run hot. However lack of 4th and lack of TCC lock up will heat them up too much.

I would check the RPM speed sensors on the transmission for the wire insulation falling off near the connectors. Two of them driver's side front and back of trans.

Possible gear selector switch failure - a scanner could see this - Selecting 2nd by bad switch when you are in 4th... Check grounds esp the one by the trans oil dipstick. Have codes read by a trans shop? Otherwise I suspect a computer failure due to lack of codes.

 

[Turbine Doc]

I re-read post missed the extra trans cooler with fan 1st go round, you've got something going on there out of normal, as my setup very similar with remote mounted trans cooler/fan, never goes over 200F per my in pan sensor even towing on 100+ F ambient days. I'm with BJ & WW on 1st steps of diagnostics, might be worth a call to Suncoast they do a lot of 4L80E work and possibly have some ideas.

 

[great white]

You know, 4l80E's also have an issue with trans oil leaking into the electrical connector on the side of the trans.

There's an "O" ring on the back side of the trans connector that weeps over time.

Once the fluid gets into the connector, all kinds of weird things can happen. "Limp mode" without a code is even possible.

It might be worth your while to sneak under there and pull the plug off to have a look. Especially if you have "wetness" (fluid) on the drivers side of the trans that you're not really sure where it's coming from.

A blast of electrical cleaner can clear out any fluid (if there is any in there) and make it work until the fluid becomes a problem again.

The problem is the "O" ring on the internal wiring harness in the housing itself. Unfortunately, the only permanent fix is to replace the o-ring. To do that, you have to open up the trans and replace it. To add to the PITA factor, the internal harness connectors are usually brittle from age and heat. So much so that they often break. Then you have to replace the harness...:rolleyes5: