what is code P1870?

[hpnotic]

I was out on a road trip yesterday and my check engine light came on.  I also noticed that it started shifting hard from 1st to 2nd gear and also from 2nd to 3rd at low acceleration.  I had been driving my truck for about three hours so the engine was pretty hot.   I checked the trans and didn't see any metal filings and the fluid didn't smell burnt at all.  Does this sound like a major problem or can it be something like a bad sensor or something minor that can be causing the problem.  I'm pretty mechanically inclined and have a lot of mechs around to ask for advice or help.  I would like to get this problem fixed without breaking my bank.  And I have a 02 Z71 with about 110k on it now.  I also just had my rear end repair if that might help with a diagnostic.  If there are any ideas on what I can do to fix myself please let me know, I would greatly appreciate the 

[ygmn]

Do any gages act funny?

[AVid]

Info - Diagnostic Information on DTC P1870 #02-07-30-001
Diagnostic Information on DTC P1870
2000-2002 Passenger Cars and Light Duty Trucks

with a 4L60E or 4L65E Automatic Transmission

Diagnostic trouble code (DTC) P1870, Transmission Component Slipping, may
have different root causes. The following diagnostic tips are provided to
assist in accurately repairing the condition.

Corporate Bulletin Number 01-07-30-023A, dated November 2001, is intended
for 1996-1999 vehicles with more than 32,000 km (20,000 mi). This bulletin
addresses wear in the valve body TCC isolator/regulator bore which can
cause DTC P1870. This wear condition is not the cause of DTC P1870 on any
2000 model year vehicle built after January 15, 2000, or any 2001 or 2002
vehicles as the valve body used on these vehicles has been revised to
prevent the wear condition.
Corporate Bulletin Number 99-07-30-005, dated March 1999, should be used
to help with diagnosis of this DTC. This bulletin will help to determine
if the DTC is caused by the TCC system or by a slipping internal
transmission component such as a clutch or band.
A plugged or restricted TCC apply fluid orifice (238, located in the pump)
may cause DTC P1870, especially in low mileage vehicles with less than
8,000 km (5,000 mi).
A converter clutch valve (224, located in the pump) which does not have
full travel of 13 mm (0.5 in) or is stuck in the off position may cause
DTC P1870. Inspect the valve for chips, debris, nicks or burrs. Also,
inspect the springs (225 and 226) to make sure they are not limiting valve
travel. A spring that is not fully wound may catch in the bore, limit
valve travel and cause DTC P1870.
A cracked or leaking TCC solenoid (part of harness 66) may cause DTC
P1870. Use solenoid test kit J 44246 to test the operation of this
solenoid.
A cracked or leaking TCC PWM solenoid (396) may also cause DTC P1870.
When attempting to diagnose a DTC P1870, it is important to also refer to
the appropriate Service Manual for further possible causes of this
condition.

[hpnotic]

No my gauge doesn't act funny.  No spike in rpms at all.  Every thing is normal with the gauge.

[sperry]

Regardless of the set codes, gauges acting funny or not, ...or the like. With the trans problems you describe, I would first check the ignition switch before doing anything other than what you tried with the trans.

Monitor the switched voltages if possible, or better yet, with the usage you have on your Av @ 110K, I would just replace the ign switch anyway.

Then, if you're certain the voltages are correct at the trans, troubleshoot it as you were. Especially with close attention to the P1870 bulletin Avid posted.

[hpnotic]

Is this a problem that needs to be addressed right away or do I have some time with it before the repair should be done?  I know you should get things fixed right away but is this something that's really not to serious, or should I park my truck at the shop to get fixed right now?

[sennister]

Is this a problem that needs to be addressed right away or do I have some time with it before the repair should be done?  I know you should get things fixed right away but is this something that's really not to serious, or should I park my truck at the shop to get fixed right now?

I would do it sooner than later. It could be hard on the tranny to let it go.

[wrench115]

I answered this for you in your original post http://www.chevyavalanchefanclub.com/cafcna/index.php/topic,66842.0.html

I'll repost it here for you. I don't know if you're skipping over it or if it's something you just don't really want to see but...

The two most common failures for this code, in the 4l60e that you have, would be.

1. Valve body it's self. The TCC signal valve wears out the bore fluid slips past and you get an excessive slip speed reading.

2. The TCC PWM valve in the pump. This one is rare, but I have seen 2-3 fail and not regulate apply pressure.

EDIT: I also remembered one more thing. This one is less common but due to your mileage it may apply. The transmission pump bushings that seal against the input shaft MAY be worn out causing a fluid pressure loss when hot. I've run into this one a few times on higher mileage rear wheel drive vehicles with the 4l60e in them.

If you can gain access to a scan tool. Watch TCC slip speed at 45-50 mph maintaining a steady speed. When the TCC is engaged slip speed should drop to 0. It may spike to around 40-50 but SHOULD not exceed 100 RPMS. If it exceeds 100 RPMS but not in excess of 200 RPMS it's a TCC signal valve worn out in the valve body.

If it exceeds 200 RPMS chances are you are losing apply pressure internally. For example stator shaft bushings in the pump. Or possibly a busted Stator inside the convertor.

If it is just the signal valve you have two options you can purchase a repair kit for the valve body. Or replace the valve body.

Doing a corvette 2-4 servo swap will not fix this problem. The rear end in no way shape or form will cause or fix this problem.

What is happening is the PCM monitors TCC slip speed for excessive RPMS anything over 100 RPMS for 10 seconds it pops the code. It has to see 2 consecutive failures or an extended failure to pop a light.

Just a little warning though. If you don't know or have never worked on a transmission. I HIGHLY suggest you have someone familiar with them to do the repairs. A small grain of sand can destroy an entire transmission.
There is another "fix" that GM came out with prior to the 2000 model year. It requires drilling a small hole inside of a cap in the valve body. I haven't actually done this in awhile since it can sometimes lead to a "hunting" sensation or a "5th" gear shift when the TCC engages.

And in answer to the question can I ignore this will it cause a bigger issue? Yes the torque convertor slip speed is excessive. It will over heat the convertor leading to a failure. You will eventually overheat and shorten the life of clutches.

Take my advice or don't. It's your truck. The problem can't be patched.

[sperry]

Now that's some really well put, helpful info.. 

[hpnotic]

I appreciate the great advice wrench115.  I will have it looked at.  The truck is in great condition except for what's going on right now.  Thanks on the input.

[hpnotic]

I got another question with this problem.  I was leaving work to take my lunch break and the check engine light went out   What does that mean, is that good or bad.  Does the computer clear the code itself after being on for a while or is it something else.  I appreciate any input on this one.  I'm still getting my truck look at this weekend.

[sperry]

If there are no recurring instances of what set the code(s) after 50, 100 or 200 ign on/off cycles (depends on what it is), the MIL will extinguish.

[rK99]

My recent problem with my ignition (eventually revealed to be the knock sensor) caused my light to come on and occasionally go out.  It had been on for at least a week straight when the dealer fixed it.

[sperry]

Some are brief and just come & go. If the problem repeats, then the code sets.

I do believe the KS fault is one of those. Why? Perhaps so a code doesn't set with bad fuel?

Somewhere I had a list or table of the criteria and levels of MIL operation, code storage and such.

[sperry]

Here's some PCM info for the reading. Some explanation on DTC's are near the end of the article.

[hpnotic]

Thanks sperry that was really helpful

[hpnotic]

Well it took me a while to respond, just getting back off a little deployment.  But I called AAMCO for a estimate and it was sky high.  So I found another shop here in my area.  They diagnosed the problem and said that I need a new throttle body.  Paid around $300 for the repair.  Got my baby back this morning and she is riding great.  The shifts are smooth and I no longer have to worry about the hard shifting from the gears.  Thanks for all the advice everyone.  Greatly appreciated.