4L60E P1870 Code. Repair questions

[ClubHuntRed]

Hi,

Truck went in limp mode. Had to drive about 20 miles at 55 mph this way... Pretty sure tranny fluid burned a little during this. no matter have to replace anyway now.

Pretty sure P1870 means Torque Converter Clutch Isolator valve. Found a replacement part that doesnt require any machining for about 14 dollars.

Several questions:

1. can this be done with the trans in the truck? My biggest concern is the valve ball stuff. Will they stay in the right place if I just remove the valve body carefully or fall out everywhere and be a nightmare to find?

2. Will the new TCC isolaator valve slide right in with tranny still in the truck?

2. I am fairly good at mechanical tasks. Viewed a video on this that was very helpful. Is there anything I need to watch out for?

3. What else should I do while there? Solenoid A/B or just leave it alone?

4. I've heard mention of the Sunshell gear. Obviously, this means removal of trans... Don't want that. Is there a way I can find out if I got the durable sunshell (years that got crap and others that got good?)

BTW my truck is a 1996 C1500 4.3L vortec 4L60E with 177,000 miles all stock.

Thanks for any comments!

 

[ClubHuntRed]

If this helps, the replacement part I am looking at is the Teckpak A74741Q.

It is said they may have a way to replace this part without removing the valve body. I will contact them and see what they say about this.


If anyone can chime in on the questions that would be great and really help me out.

 

[rhino]

I have never replaced one without pulling the valve body... But its not a hard task. Just remove the pan, then remove the filter and unplug your solenoids. Remove all the bolts holding the valve body, 7 balls will come falling out. They are easy to put back, and very noticeable where they go. I have a diagram if you can't find one. The tech pack valve is what we use in every unit we build. Very good fix. There is no way to check your sun shell however. The ones that were bad were from 1984-2012. We did a 2008 last week with a stripped shell. It's just a weak spot because its turning one way in reverse, another way in drive. So if your backing up and don't come to a complete stop every time before you put it in drive it puts a lot of stress on the splines. My only concern....is P1870 code won't put the transmission into limp mode. It will make the engine light come on sometimes, and it freezes the pressure control solenoid to max which gives you a firm shift. Was that the only code it showed?

 

[ClubHuntRed]

Yes, P1870 was the only code that was shown.

I was getting on the hwy, it went into OD momentarily then violently shifted into 3rd. I actually thought I had been hit from behind...

Went 20 miles this way. Drove 55 in a 75 to keep the RPMs down to 2000 (which means either slipping badly in 4th or in 3rd). Took 15 miles before the CEL came on. I was very worried about the fluid and the tranny pan was very hot to the touch when I parked it.

It was also a nightmare to drive from a stop. It was taking off from 1? and very violently shifted into 3rd. Not fun...

Am I mistaken with my diagnosis? What do you think it is?

I'm confused by your statement "p1870 won't cause limp mode". From my research into the issue, and to the best of my knowledge, the truck went into limp mode. I borrowed a scanner from AutoZone and p1870 is the only code showing.

Thanks for your reply!

 

[rhino]

When you were taking off from a stop, did it feel like it was taking off in low gear?

 

[rhino]

The tricky part about P1870 code, is that the code definition is transmission component slipping. 90 percent of the time, it sets when the PCM detects a slip in the torque converter. It then sets the code, commands high line pressure to prevent internal damage to the transmission. But... We have seen a P1870 code from the band slipping also. If the PCM notices a slip, for however many seconds for I think it's 3 consecutive starts, it will set the code. Normally, when people lose a gear they park it before the code pops in or you lose the gear entirely and the PCM thinks it's in the right gear so no code is set. How does it shift since you got it home and it cooled off?

 

[ClubHuntRed]

I am not sure about the low gear part. I think yes. I would take off slowly and it wouldn't shift until something like 2500 RPM at ~20mph. So I'm assuming it stayed in 1st until it was traveling fast enough to go into 3rd.

I have not driven it since parking it. Should I go drive it? What should I pay attention to to help with diagnosis?

 

[ClubHuntRed]

When I say take off slowly, I mean as gentle as possible (like a grandma)

 

[rhino]

Main thing is see what gears it does have. If it only has 1st and 3rd gear, it's probably going to be the band burnt. Limp mode, is second and third gear only, so if it's in limp, it will feel sluggish taking off. If the bands burnt, it will take off in low, run up high on the rpm, then shift straight to third. Skipping second.

 

[ClubHuntRed]

ah S%!+, No way it might just be a A or B solenoid? (not sure). or anything else?

I might just take it to a tranny shop but I want to ask this. I'm thinking about putting in a 4l80e instead of rebuilding this one. I plan to swap in 5.3 or 6.0 down the road when the engine goes kaput. The engine still runs like a champ so that'll give me time to find a good engine.

So question now is, can a 4l80e be swapped onto a 96 vortec (I think tranny mount needs fabricated, extended tranny line, driveshaft????)

On to the search function....