10W30 - Auto Repair Answers and Archive

jerryg2314 · 10-07-2008 10:48 PM

The vehicle has an auto trans. After driving at highway speeds for 10-15 minutes, it slips from overdrive to drive, and back to overdrive. Only seems to do this at speeds over 60 mph, and with no pattern. The fluid level is good and it is clean, and the filter was changed about 6 months ago. I found a vacuum line disconnected, but did not seem to have an affect. A guy at Advanced Auto parts scanned the truck and got a P1870 code, which means Transmission Component Slipping. Anyone familiar with this, or can recommend a remedy, besides taking it to a dealer? I love the truck, but it has 180,000 miles on it and I need to find out if I can fix it myself, or scrap it. Thanks.

**re-tired** · 10-07-2008 11:38 PM

Sounds like an internal failure , most likely a servo ,valve or clutch. It would not be a DIY project . To many specialized tools and jigs required for teardown and reassembly. Also because many parts are not reuseable and ths large number of seals and gaskets any teardown becomes a overhaul . Your only viable option would be a salvage yard unit .Hopefully then you could handle the R&R. Just in case there is a common easy fix such as a valve body retorque or similar , I would talk to a couple of shops for a ballpark est , without a teatdown till your ready.

jgate · 10-08-2008 12:43 AM

With the 4L60E trans, a better and most complete definition of a DTAC 1870 code is actually the TACC PWM solenoid failure. Mostly with this code what I have found to happen is when the TACC is "on", the PWM solenoid is in charge of activating 3 valves simultaneously, the TACC control valve, The TACC enable valve that controls the spring side of the of the TACC control valve and the exhaust path,and the TACC regulator valve, that controls the TACC apply pressure. The DTAC P1870 is set because of excessive wear in the TACC regulator valve sleeve, and causes a loss or TACC apply pressure.
Is the P1870 the only code you were able to retrieve from your TACM side?
Or was this code retrieved from the main PCM.
If you do decide to get one from a salvage yard, you are really limited to years 96 and 97 and maybe early 98, this trans has gone through a lot of changes over the years.

**re-tired** · 10-08-2008 05:05 PM

Thats what I meant :roll: . Jeeze , talk about a good answer, well said jgate :wink: . I now shall quietly fade into the background . Gee maybe someone will ask bout fishing 8) .

**crank.it** · 10-08-2008 06:44 PM

DANG WOODY..... :lol: :lol: :lol: :lol: crank.it

jerryg2314 · 10-08-2008 08:43 PM

I am assuming the code was taken from the main PCM, because it also gave me an o2 sensor code, but those were the only 2. Is my best bet to start looking for a salvage tranny? I am pretty handy, but this would definitely be the biggest project I have attempted (a tranny removal and reinstall, I mean). I was hoping for a sensor or something, but I don't know much about transmissions so I wasn't really sure where to start.

jgate · 10-09-2008 12:39 PM

When it comes right down to it , you are the one that is going to have to make the decision.
I have a few things to consider though. You did post that this vehicle had 180,000 miles on it.
At that many miles on this trans if it is the original trans, (really kind of unlikely) the valve bores in the valve body,like the pressure control solenoid bore, the AFL valve bore, and of course the the TACC pressure regulator valve, and the servo like the 1/2 and the 3/4 servo bore will be worn. You also have the 1-2 and the 3-4 accumulator bores, that will show wear ,there are a lot of valves in this trans and you can expect wear on all of these bores and valves. you can have these worn bores sleeved,or buy a new valve body, And actually at this point a new pump. a good transmission technician, will know what bores and vales are worn.
Which will be more dollars than just doing a basic master overhaul.
Then on the other hand , how long are planing on keeping this truck? and how good is the rest of the drive-train, the body, and suspension?
And finding a 4L60E trans with low mileage from a salvage yard would be a challenge, and of course the lower the mileage the higher the price, I would call around and get some prices and don't forget to ask the mileage that is on the trans.
If you can do the R&R of the trans and finding a low mileage trans from 96-97 or maybe early 98, this might be your better solution.
And even with a salvage yard trans I would strongly suggest to at least install a reman torque converter.

hushklein · 01-14-2012 05:14 AM

actually my friend have this problem, difficulty in gmc accessories bleeding a clutch. and found this one, clutch systems bleed just like brakes, if you have an external leak at the clutch master cylinder, then bleeding will be difficult, it should be replaced. I use a two person bleeding system, I fill the master, crack the bleeder screw open and have my 2nd push the clutch down and hold it, then I close the bleeder and tell my 2nd to release the pedal, repeat until no air is present.